From seed foraging to plant removal. Pogos
interacting with the plant life around them, in North America.
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***There may be multiple image pages; use red page/image controls below to see them all!***
![pogolumina > ● NW of Mattawa [Grant Co], WA USA [el. 152 m / 500 ft] view location in Google Maps »
● 5/9/10 12:15PM sunny, air temp: [not measured]
Silhouetted against the bright background, this P. salinus worker searches a fiddleneck plant (Amsinckia sp.) for nectar, in central Washington state.](http://www.pogolumina.net/NorthAmericanPogosbyBehavior/Plants/i-rtn3jN7/0/Ti/3360_10_7Df-Ti.jpg "pogolumina > ● NW of Mattawa [Grant Co], WA USA [el. 152 m / 500 ft] view location in Google Maps »
● 5/9/10 12:15PM sunny, air temp: [not measured]
Silhouetted against the bright background, this P. salinus worker searches a fiddleneck plant (Amsinckia sp.) for nectar, in central Washington state.")
![pogolumina > ● Wanapum Rec. Area [Kittitas Co], WA USA [el. 190 m / 623 ft] view location in Google Maps »
● 4/19/10 11:01AM sun, haze, air temp: 22°C / 72°F
[IMAGE 1 of 4 - same description for these 4 images] Spring is a busy time for Pogonomyrmex salinus workers. While some colony members forage, or conduct maintenance on the nest below, others engage in the removal of plants that have sprung up on, or too close to the nest mound. Even with their powerful mandibles, these ants struggle to cut through tough plant stems, and leaves. This series of images was captured on our first outing of 2010, in Washington state. A dozen or so workers from a small nest were busy cutting down cheatgrass (Bromus tectorum) growing on, and around the edges of the nest mound [see additional images » ]. One worker was seen attempting to drag a bunch of fallen spikelets, possibly back to the nest - though it was unclear, as she was making no progress, and soon abandoned the effort. [scroll down for additional notes/references]
ADDITIONAL NOTES/REFERENCES:
The introduced (and invasive) grass Bromus tectorum (cheatgrass), is common in many of the areas inhabited by Pogonomyrmex ants, and is often a target of their foraging activities.
One study in central Oregon found cheat grass (Bromus tectorum), to be one of the 5 most frequently collected seeds by P. salinus. The others were: Phacelia linearis, Hordeum jubatum, Descurainia pinnata, and Sisymbrium altissimum.
Pogonomyrmex occidentalis (a member of the same complex as P. salinus) has long been known to have an association with Bromus tectorum, though there are indications that this ant prefers other species when they are available. In the Twin Falls, Idaho area, Cole found the seeds of B. tectorum to be harvested in great quantities "...primarily due to the predominance of Bromus tectorum in the semi-desert areas." He also notes that "the seed chambers of mounds in dense bromegrass areas often contain a greater quantity of other seeds and only a few colonies were located which seemed to harvest bromegrass seeds exclusively."
This seems to be in keeping with the preliminary findings of a study of P. occidentalis in Colorado, by D. Wiernasz, where it was found that "Bromus tectorum was strongly avoided, and never exceeded 3% of seeds collected by foragers, even in high density areas."
·Cole, A.C. 1932a. The Relation of the Ant, Pogonomyrmex occidentalis CR., to its Habitat. Ohio Journal of Science, 32:133-46, Ohio State University
·Wiernasz, D. 2005. Granivore Activity on the Invasive Grass Bromus tectorum: a Factor in Establishment or Exclusion? University of Huston
·Willard, J.R. & H.H. Crowell. 1965. Biological Activities of the Harvester Ant, Pogonomyrmex owyheei, in Central Oregon. Journal of Economic Entomology Vol.58, No.3](http://www.pogolumina.net/NorthAmericanPogosbyBehavior/Plants/i-Tw8SZnL/1/Ti/2860_10_7Df-Ti.jpg "pogolumina > ● Wanapum Rec. Area [Kittitas Co], WA USA [el. 190 m / 623 ft] view location in Google Maps »
● 4/19/10 11:01AM sun, haze, air temp: 22°C / 72°F
[IMAGE 1 of 4 - same description for these 4 images] Spring is a busy time for Pogonomyrmex salinus workers. While some colony members forage, or conduct maintenance on the nest below, others engage in the removal of plants that have sprung up on, or too close to the nest mound. Even with their powerful mandibles, these ants struggle to cut through tough plant stems, and leaves. This series of images was captured on our first outing of 2010, in Washington state. A dozen or so workers from a small nest were busy cutting down cheatgrass (Bromus tectorum) growing on, and around the edges of the nest mound [see additional images » ]. One worker was seen attempting to drag a bunch of fallen spikelets, possibly back to the nest - though it was unclear, as she was making no progress, and soon abandoned the effort. [scroll down for additional notes/references]
ADDITIONAL NOTES/REFERENCES:
The introduced (and invasive) grass Bromus tectorum (cheatgrass), is common in many of the areas inhabited by Pogonomyrmex ants, and is often a target of their foraging activities.
One study in central Oregon found cheat grass (Bromus tectorum), to be one of the 5 most frequently collected seeds by P. salinus. The others were: Phacelia linearis, Hordeum jubatum, Descurainia pinnata, and Sisymbrium altissimum.
Pogonomyrmex occidentalis (a member of the same complex as P. salinus) has long been known to have an association with Bromus tectorum, though there are indications that this ant prefers other species when they are available. In the Twin Falls, Idaho area, Cole found the seeds of B. tectorum to be harvested in great quantities \"...primarily due to the predominance of Bromus tectorum in the semi-desert areas.\" He also notes that \"the seed chambers of mounds in dense bromegrass areas often contain a greater quantity of other seeds and only a few colonies were located which seemed to harvest bromegrass seeds exclusively.\"
This seems to be in keeping with the preliminary findings of a study of P. occidentalis in Colorado, by D. Wiernasz, where it was found that \"Bromus tectorum was strongly avoided, and never exceeded 3% of seeds collected by foragers, even in high density areas.\"
·Cole, A.C. 1932a. The Relation of the Ant, Pogonomyrmex occidentalis CR., to its Habitat. Ohio Journal of Science, 32:133-46, Ohio State University
·Wiernasz, D. 2005. Granivore Activity on the Invasive Grass Bromus tectorum: a Factor in Establishment or Exclusion? University of Huston
·Willard, J.R. & H.H. Crowell. 1965. Biological Activities of the Harvester Ant, Pogonomyrmex owyheei, in Central Oregon. Journal of Economic Entomology Vol.58, No.3")
![pogolumina > ● Wanapum Rec. Area [Kittitas Co], WA USA [el. 190 m / 623 ft] view location in Google Maps »
● 4/19/10 12:17PM sun, haze, air temp: 25°C / 77°F
[IMAGE 2 of 4 - same description for these 4 images] Spring is a busy time for Pogonomyrmex salinus workers. While some colony members forage, or conduct maintenance on the nest below, others engage in the removal of plants that have sprung up on, or too close to the nest mound. Even with their powerful mandibles, these ants struggle to cut through tough plant stems, and leaves. This series of images was captured on our first outing of 2010, in Washington state. A dozen or so workers from a small nest were busy cutting down cheatgrass (Bromus tectorum) growing on, and around the edges of the nest mound [see additional images » ]. One worker was seen attempting to drag a bunch of fallen spikelets, possibly back to the nest - though it was unclear, as she was making no progress, and soon abandoned the effort. [scroll down for additional notes/references]
ADDITIONAL NOTES/REFERENCES:
The introduced (and invasive) grass Bromus tectorum (cheatgrass), is common in many of the areas inhabited by Pogonomyrmex ants, and is often a target of their foraging activities.
One study in central Oregon found cheat grass (Bromus tectorum), to be one of the 5 most frequently collected seeds by P. salinus. The others were: Phacelia linearis, Hordeum jubatum, Descurainia pinnata, and Sisymbrium altissimum.
Pogonomyrmex occidentalis (a member of the same complex as P. salinus) has long been known to have an association with Bromus tectorum, though there are indications that this ant prefers other species when they are available. In the Twin Falls, Idaho area, Cole found the seeds of B. tectorum to be harvested in great quantities "...primarily due to the predominance of Bromus tectorum in the semi-desert areas." He also notes that "the seed chambers of mounds in dense bromegrass areas often contain a greater quantity of other seeds and only a few colonies were located which seemed to harvest bromegrass seeds exclusively."
This seems to be in keeping with the preliminary findings of a study of P. occidentalis in Colorado, by D. Wiernasz, where it was found that "Bromus tectorum was strongly avoided, and never exceeded 3% of seeds collected by foragers, even in high density areas."
·Cole, A.C. 1932a. The Relation of the Ant, Pogonomyrmex occidentalis CR., to its Habitat. Ohio Journal of Science, 32:133-46, Ohio State University
·Wiernasz, D. 2005. Granivore Activity on the Invasive Grass Bromus tectorum: a Factor in Establishment or Exclusion? University of Huston
·Willard, J.R. & H.H. Crowell. 1965. Biological Activities of the Harvester Ant, Pogonomyrmex owyheei, in Central Oregon. Journal of Economic Entomology Vol.58, No.3](http://www.pogolumina.net/NorthAmericanPogosbyBehavior/Plants/i-qkMc9MT/3/Ti/2905_10_7Dc-Ti.jpg "pogolumina > ● Wanapum Rec. Area [Kittitas Co], WA USA [el. 190 m / 623 ft] view location in Google Maps »
● 4/19/10 12:17PM sun, haze, air temp: 25°C / 77°F
[IMAGE 2 of 4 - same description for these 4 images] Spring is a busy time for Pogonomyrmex salinus workers. While some colony members forage, or conduct maintenance on the nest below, others engage in the removal of plants that have sprung up on, or too close to the nest mound. Even with their powerful mandibles, these ants struggle to cut through tough plant stems, and leaves. This series of images was captured on our first outing of 2010, in Washington state. A dozen or so workers from a small nest were busy cutting down cheatgrass (Bromus tectorum) growing on, and around the edges of the nest mound [see additional images » ]. One worker was seen attempting to drag a bunch of fallen spikelets, possibly back to the nest - though it was unclear, as she was making no progress, and soon abandoned the effort. [scroll down for additional notes/references]
ADDITIONAL NOTES/REFERENCES:
The introduced (and invasive) grass Bromus tectorum (cheatgrass), is common in many of the areas inhabited by Pogonomyrmex ants, and is often a target of their foraging activities.
One study in central Oregon found cheat grass (Bromus tectorum), to be one of the 5 most frequently collected seeds by P. salinus. The others were: Phacelia linearis, Hordeum jubatum, Descurainia pinnata, and Sisymbrium altissimum.
Pogonomyrmex occidentalis (a member of the same complex as P. salinus) has long been known to have an association with Bromus tectorum, though there are indications that this ant prefers other species when they are available. In the Twin Falls, Idaho area, Cole found the seeds of B. tectorum to be harvested in great quantities \"...primarily due to the predominance of Bromus tectorum in the semi-desert areas.\" He also notes that \"the seed chambers of mounds in dense bromegrass areas often contain a greater quantity of other seeds and only a few colonies were located which seemed to harvest bromegrass seeds exclusively.\"
This seems to be in keeping with the preliminary findings of a study of P. occidentalis in Colorado, by D. Wiernasz, where it was found that \"Bromus tectorum was strongly avoided, and never exceeded 3% of seeds collected by foragers, even in high density areas.\"
·Cole, A.C. 1932a. The Relation of the Ant, Pogonomyrmex occidentalis CR., to its Habitat. Ohio Journal of Science, 32:133-46, Ohio State University
·Wiernasz, D. 2005. Granivore Activity on the Invasive Grass Bromus tectorum: a Factor in Establishment or Exclusion? University of Huston
·Willard, J.R. & H.H. Crowell. 1965. Biological Activities of the Harvester Ant, Pogonomyrmex owyheei, in Central Oregon. Journal of Economic Entomology Vol.58, No.3")
![pogolumina > ● Wanapum Rec. Area [Kittitas Co], WA USA [el. 190 m / 623 ft] view location in Google Maps »
● 4/19/10 12:31PM sun, haze, air temp: 25°C / 77°F
[IMAGE 3 of 4 - same description for these 4 images] Spring is a busy time for Pogonomyrmex salinus workers. While some colony members forage, or conduct maintenance on the nest below, others engage in the removal of plants that have sprung up on, or too close to the nest mound. Even with their powerful mandibles, these ants struggle to cut through tough plant stems, and leaves. This series of images was captured on our first outing of 2010, in Washington state. A dozen or so workers from a small nest were busy cutting down cheatgrass (Bromus tectorum) growing on, and around the edges of the nest mound [see additional images » ]. One worker was seen attempting to drag a bunch of fallen spikelets, possibly back to the nest - though it was unclear, as she was making no progress, and soon abandoned the effort. [scroll down for additional notes/references]
ADDITIONAL NOTES/REFERENCES:
The introduced (and invasive) grass Bromus tectorum (cheatgrass), is common in many of the areas inhabited by Pogonomyrmex ants, and is often a target of their foraging activities.
One study in central Oregon found cheat grass (Bromus tectorum), to be one of the 5 most frequently collected seeds by P. salinus. The others were: Phacelia linearis, Hordeum jubatum, Descurainia pinnata, and Sisymbrium altissimum.
Pogonomyrmex occidentalis (a member of the same complex as P. salinus) has long been known to have an association with Bromus tectorum, though there are indications that this ant prefers other species when they are available. In the Twin Falls, Idaho area, Cole found the seeds of B. tectorum to be harvested in great quantities "...primarily due to the predominance of Bromus tectorum in the semi-desert areas." He also notes that "the seed chambers of mounds in dense bromegrass areas often contain a greater quantity of other seeds and only a few colonies were located which seemed to harvest bromegrass seeds exclusively."
This seems to be in keeping with the preliminary findings of a study of P. occidentalis in Colorado, by D. Wiernasz, where it was found that "Bromus tectorum was strongly avoided, and never exceeded 3% of seeds collected by foragers, even in high density areas."
·Cole, A.C. 1932a. The Relation of the Ant, Pogonomyrmex occidentalis CR., to its Habitat. Ohio Journal of Science, 32:133-46, Ohio State University
·Wiernasz, D. 2005. Granivore Activity on the Invasive Grass Bromus tectorum: a Factor in Establishment or Exclusion? University of Huston
·Willard, J.R. & H.H. Crowell. 1965. Biological Activities of the Harvester Ant, Pogonomyrmex owyheei, in Central Oregon. Journal of Economic Entomology Vol.58, No.3](http://www.pogolumina.net/NorthAmericanPogosbyBehavior/Plants/i-J2rbtMC/4/Ti/2943_10_7Df-Ti.jpg "pogolumina > ● Wanapum Rec. Area [Kittitas Co], WA USA [el. 190 m / 623 ft] view location in Google Maps »
● 4/19/10 12:31PM sun, haze, air temp: 25°C / 77°F
[IMAGE 3 of 4 - same description for these 4 images] Spring is a busy time for Pogonomyrmex salinus workers. While some colony members forage, or conduct maintenance on the nest below, others engage in the removal of plants that have sprung up on, or too close to the nest mound. Even with their powerful mandibles, these ants struggle to cut through tough plant stems, and leaves. This series of images was captured on our first outing of 2010, in Washington state. A dozen or so workers from a small nest were busy cutting down cheatgrass (Bromus tectorum) growing on, and around the edges of the nest mound [see additional images » ]. One worker was seen attempting to drag a bunch of fallen spikelets, possibly back to the nest - though it was unclear, as she was making no progress, and soon abandoned the effort. [scroll down for additional notes/references]
ADDITIONAL NOTES/REFERENCES:
The introduced (and invasive) grass Bromus tectorum (cheatgrass), is common in many of the areas inhabited by Pogonomyrmex ants, and is often a target of their foraging activities.
One study in central Oregon found cheat grass (Bromus tectorum), to be one of the 5 most frequently collected seeds by P. salinus. The others were: Phacelia linearis, Hordeum jubatum, Descurainia pinnata, and Sisymbrium altissimum.
Pogonomyrmex occidentalis (a member of the same complex as P. salinus) has long been known to have an association with Bromus tectorum, though there are indications that this ant prefers other species when they are available. In the Twin Falls, Idaho area, Cole found the seeds of B. tectorum to be harvested in great quantities \"...primarily due to the predominance of Bromus tectorum in the semi-desert areas.\" He also notes that \"the seed chambers of mounds in dense bromegrass areas often contain a greater quantity of other seeds and only a few colonies were located which seemed to harvest bromegrass seeds exclusively.\"
This seems to be in keeping with the preliminary findings of a study of P. occidentalis in Colorado, by D. Wiernasz, where it was found that \"Bromus tectorum was strongly avoided, and never exceeded 3% of seeds collected by foragers, even in high density areas.\"
·Cole, A.C. 1932a. The Relation of the Ant, Pogonomyrmex occidentalis CR., to its Habitat. Ohio Journal of Science, 32:133-46, Ohio State University
·Wiernasz, D. 2005. Granivore Activity on the Invasive Grass Bromus tectorum: a Factor in Establishment or Exclusion? University of Huston
·Willard, J.R. & H.H. Crowell. 1965. Biological Activities of the Harvester Ant, Pogonomyrmex owyheei, in Central Oregon. Journal of Economic Entomology Vol.58, No.3")
![pogolumina > ● Wanapum Rec. Area [Kittitas Co], WA USA [el. 190 m / 623 ft] view location in Google Maps »
● 4/19/10 1:14PM sun, haze, air temp: 26°C / 79°F
[IMAGE 4 of 4 - same description for these 4 images] Spring is a busy time for Pogonomyrmex salinus workers. While some colony members forage, or conduct maintenance on the nest below, others engage in the removal of plants that have sprung up on, or too close to the nest mound. Even with their powerful mandibles, these ants struggle to cut through tough plant stems, and leaves. This series of images was captured on our first outing of 2010, in Washington state. A dozen or so workers from a small nest were busy cutting down cheatgrass (Bromus tectorum) growing on, and around the edges of the nest mound [see additional images » ]. One worker was seen attempting to drag a bunch of fallen spikelets, possibly back to the nest - though it was unclear, as she was making no progress, and soon abandoned the effort. [scroll down for additional notes/references]
ADDITIONAL NOTES/REFERENCES:
The introduced (and invasive) grass Bromus tectorum (cheatgrass), is common in many of the areas inhabited by Pogonomyrmex ants, and is often a target of their foraging activities.
One study in central Oregon found cheat grass (Bromus tectorum), to be one of the 5 most frequently collected seeds by P. salinus. The others were: Phacelia linearis, Hordeum jubatum, Descurainia pinnata, and Sisymbrium altissimum.
Pogonomyrmex occidentalis (a member of the same complex as P. salinus) has long been known to have an association with Bromus tectorum, though there are indications that this ant prefers other species when they are available. In the Twin Falls, Idaho area, Cole found the seeds of B. tectorum to be harvested in great quantities "...primarily due to the predominance of Bromus tectorum in the semi-desert areas." He also notes that "the seed chambers of mounds in dense bromegrass areas often contain a greater quantity of other seeds and only a few colonies were located which seemed to harvest bromegrass seeds exclusively."
This seems to be in keeping with the preliminary findings of a study of P. occidentalis in Colorado, by D. Wiernasz, where it was found that "Bromus tectorum was strongly avoided, and never exceeded 3% of seeds collected by foragers, even in high density areas."
·Cole, A.C. 1932a. The Relation of the Ant, Pogonomyrmex occidentalis CR., to its Habitat. Ohio Journal of Science, 32:133-46, Ohio State University
·Wiernasz, D. 2005. Granivore Activity on the Invasive Grass Bromus tectorum: a Factor in Establishment or Exclusion? University of Huston
·Willard, J.R. & H.H. Crowell. 1965. Biological Activities of the Harvester Ant, Pogonomyrmex owyheei, in Central Oregon. Journal of Economic Entomology Vol.58, No.3](http://www.pogolumina.net/NorthAmericanPogosbyBehavior/Plants/i-DTBFXKV/0/Ti/3005_10_7Dc-Ti.jpg "pogolumina > ● Wanapum Rec. Area [Kittitas Co], WA USA [el. 190 m / 623 ft] view location in Google Maps »
● 4/19/10 1:14PM sun, haze, air temp: 26°C / 79°F
[IMAGE 4 of 4 - same description for these 4 images] Spring is a busy time for Pogonomyrmex salinus workers. While some colony members forage, or conduct maintenance on the nest below, others engage in the removal of plants that have sprung up on, or too close to the nest mound. Even with their powerful mandibles, these ants struggle to cut through tough plant stems, and leaves. This series of images was captured on our first outing of 2010, in Washington state. A dozen or so workers from a small nest were busy cutting down cheatgrass (Bromus tectorum) growing on, and around the edges of the nest mound [see additional images » ]. One worker was seen attempting to drag a bunch of fallen spikelets, possibly back to the nest - though it was unclear, as she was making no progress, and soon abandoned the effort. [scroll down for additional notes/references]
ADDITIONAL NOTES/REFERENCES:
The introduced (and invasive) grass Bromus tectorum (cheatgrass), is common in many of the areas inhabited by Pogonomyrmex ants, and is often a target of their foraging activities.
One study in central Oregon found cheat grass (Bromus tectorum), to be one of the 5 most frequently collected seeds by P. salinus. The others were: Phacelia linearis, Hordeum jubatum, Descurainia pinnata, and Sisymbrium altissimum.
Pogonomyrmex occidentalis (a member of the same complex as P. salinus) has long been known to have an association with Bromus tectorum, though there are indications that this ant prefers other species when they are available. In the Twin Falls, Idaho area, Cole found the seeds of B. tectorum to be harvested in great quantities \"...primarily due to the predominance of Bromus tectorum in the semi-desert areas.\" He also notes that \"the seed chambers of mounds in dense bromegrass areas often contain a greater quantity of other seeds and only a few colonies were located which seemed to harvest bromegrass seeds exclusively.\"
This seems to be in keeping with the preliminary findings of a study of P. occidentalis in Colorado, by D. Wiernasz, where it was found that \"Bromus tectorum was strongly avoided, and never exceeded 3% of seeds collected by foragers, even in high density areas.\"
·Cole, A.C. 1932a. The Relation of the Ant, Pogonomyrmex occidentalis CR., to its Habitat. Ohio Journal of Science, 32:133-46, Ohio State University
·Wiernasz, D. 2005. Granivore Activity on the Invasive Grass Bromus tectorum: a Factor in Establishment or Exclusion? University of Huston
·Willard, J.R. & H.H. Crowell. 1965. Biological Activities of the Harvester Ant, Pogonomyrmex owyheei, in Central Oregon. Journal of Economic Entomology Vol.58, No.3")
![pogolumina > ● Castolon [Loc 41] Big Bend N.P., TX USA [el. 660 m / 2164 ft] view location in Google Maps »
● 3/06/10 10:27AM sun/haze, air temp: 18°C / 64°F
Though too early in the season for new seeds to be available (at this location), these P. desertorum workers could be seen inspecting, and even transporting dry bits of plant matter. We did not observe any of this material being taken into the nest, however. [scroll down for additional notes/references]
ADDITIONAL NOTES/REFERENCES:
The integument (outer body covering) of these P. desertorum workers was quite translucent. When back-lit by the sun (as can be seen in some of these images), these ants glowed with the most beautiful orange-red color. In some cases, x-ray-like hints of their internal anatomy could be seen as well.](http://www.pogolumina.net/NorthAmericanPogosbyBehavior/Plants/i-9cRGRLs/7/Ti/IMG_2176_10_7Df-Ti.jpg "pogolumina > ● Castolon [Loc 41] Big Bend N.P., TX USA [el. 660 m / 2164 ft] view location in Google Maps »
● 3/06/10 10:27AM sun/haze, air temp: 18°C / 64°F
Though too early in the season for new seeds to be available (at this location), these P. desertorum workers could be seen inspecting, and even transporting dry bits of plant matter. We did not observe any of this material being taken into the nest, however. [scroll down for additional notes/references]
ADDITIONAL NOTES/REFERENCES:
The integument (outer body covering) of these P. desertorum workers was quite translucent. When back-lit by the sun (as can be seen in some of these images), these ants glowed with the most beautiful orange-red color. In some cases, x-ray-like hints of their internal anatomy could be seen as well.")
![pogolumina > ● NW of Mattawa [Grant Co], WA USA [el. 152 m / 500 ft] view location in Google Maps »
● 5/9/10 10:14AM 50% cloud, air temp: 16°C / 61°F
[IMAGE 1 of 4] The seeds of western tansy-mustard (Descurainia sp.) are apparently a very important source of food for the Pogonomyrmex salinus ants of central Washington state. This series of four images was captured in the space of less than one minute - as a determined worker removed a relatively huge seed-pod from a living plant near her nest. Using her legs and gaster (large abdominal body part) to maximize leverage, she can be seen cutting through the stem, just below the seed-pod (1st and 2nd images). Suddenly, the pod is cut free, and the ant climbs out to the end of a seed-pod below, with cargo firmly held in her mandibles (3rd and 4th images). Two seconds after the last image, she dropped to the ground (from a height of about 25 cm / 10 inches) and ran at full speed to the nest, disappearing into the entrance with her prize.
ADDITIONAL NOTES/REFERENCES:
Descurainia (tansy-mustard) species thrive in dry (and often disturbed) soils, and are quite abundant in many areas where Pogos live. Nest middens are often full of empty Descurainia seed pods. We have observed and imaged P.salinus workers interacting with these plants in several locations in Washington state. These interactions encompass a range of behaviors, including the foraging of seeds/seed pods, removal of empty seed pods from nests, and the removal of entire plants from nest mounds and adjacent areas. Pogonomyrmex salinus has also been observed to collect the seeds/seed pods of various Descurainia species in Oregon and Idaho, and one study indicates that in central Oregon, Descurainia pinnata (western tansy-mustard) is one of the 5 most frequently collected seeds by P. salinus. The others were: Bromus tectorum, Phacelia linearis, Hordeum jubatum, and Sisymbrium altissimum.
·Jorgensen C.D. & Porter, S.D. 1982. Foraging Behavior of Pogonomyrmex owyheei in Southest Idaho. Environmental Entomology, Vol. 11, No. 2, April 1982
·Willard, J.R. & H.H. Crowell. 1965. Biological Activities of the Harvester Ant, Pogonomyrmex owyheei, in Central Oregon. Journal of Economic Entomology Vol.58, No.3](http://www.pogolumina.net/NorthAmericanPogosbyBehavior/Plants/i-2qCRHc4/2/Ti/3317_10_7Df-Ti.jpg "pogolumina > ● NW of Mattawa [Grant Co], WA USA [el. 152 m / 500 ft] view location in Google Maps »
● 5/9/10 10:14AM 50% cloud, air temp: 16°C / 61°F
[IMAGE 1 of 4] The seeds of western tansy-mustard (Descurainia sp.) are apparently a very important source of food for the Pogonomyrmex salinus ants of central Washington state. This series of four images was captured in the space of less than one minute - as a determined worker removed a relatively huge seed-pod from a living plant near her nest. Using her legs and gaster (large abdominal body part) to maximize leverage, she can be seen cutting through the stem, just below the seed-pod (1st and 2nd images). Suddenly, the pod is cut free, and the ant climbs out to the end of a seed-pod below, with cargo firmly held in her mandibles (3rd and 4th images). Two seconds after the last image, she dropped to the ground (from a height of about 25 cm / 10 inches) and ran at full speed to the nest, disappearing into the entrance with her prize.
ADDITIONAL NOTES/REFERENCES:
Descurainia (tansy-mustard) species thrive in dry (and often disturbed) soils, and are quite abundant in many areas where Pogos live. Nest middens are often full of empty Descurainia seed pods. We have observed and imaged P.salinus workers interacting with these plants in several locations in Washington state. These interactions encompass a range of behaviors, including the foraging of seeds/seed pods, removal of empty seed pods from nests, and the removal of entire plants from nest mounds and adjacent areas. Pogonomyrmex salinus has also been observed to collect the seeds/seed pods of various Descurainia species in Oregon and Idaho, and one study indicates that in central Oregon, Descurainia pinnata (western tansy-mustard) is one of the 5 most frequently collected seeds by P. salinus. The others were: Bromus tectorum, Phacelia linearis, Hordeum jubatum, and Sisymbrium altissimum.
·Jorgensen C.D. & Porter, S.D. 1982. Foraging Behavior of Pogonomyrmex owyheei in Southest Idaho. Environmental Entomology, Vol. 11, No. 2, April 1982
·Willard, J.R. & H.H. Crowell. 1965. Biological Activities of the Harvester Ant, Pogonomyrmex owyheei, in Central Oregon. Journal of Economic Entomology Vol.58, No.3")
![pogolumina > ● NW of Mattawa [Grant Co], WA USA [el. 152 m / 500 ft] view location in Google Maps »
● 5/9/10 10:14AM 50% cloud, air temp: 16°C / 61°F
[IMAGE 2 of 4] The seeds of western tansy-mustard (Descurainia sp.) are apparently a very important source of food for the Pogonomyrmex salinus ants of central Washington state. This series of four images was captured in the space of less than one minute - as a determined worker removed a relatively huge seed-pod from a living plant near her nest. Using her legs and gaster (large abdominal body part) to maximize leverage, she can be seen cutting through the stem, just below the seed-pod (1st and 2nd images). Suddenly, the pod is cut free, and the ant climbs out to the end of a seed-pod below, with cargo firmly held in her mandibles (3rd and 4th images). Two seconds after the last image, she dropped to the ground (from a height of about 25 cm / 10 inches) and ran at full speed to the nest, disappearing into the entrance with her prize.
ADDITIONAL NOTES/REFERENCES:
Descurainia (tansy-mustard) species thrive in dry (and often disturbed) soils, and are quite abundant in many areas where Pogos live. Nest middens are often full of empty Descurainia seed pods. We have observed and imaged P.salinus workers interacting with these plants in several locations in Washington state. These interactions encompass a range of behaviors, including the foraging of seeds/seed pods, removal of empty seed pods from nests, and the removal of entire plants from nest mounds and adjacent areas. Pogonomyrmex salinus has also been observed to collect the seeds/seed pods of various Descurainia species in Oregon and Idaho, and one study indicates that in central Oregon, Descurainia pinnata (western tansy-mustard) is one of the 5 most frequently collected seeds by P. salinus. The others were: Bromus tectorum, Phacelia linearis, Hordeum jubatum, and Sisymbrium altissimum.
·Jorgensen C.D. & Porter, S.D. 1982. Foraging Behavior of Pogonomyrmex owyheei in Southest Idaho. Environmental Entomology, Vol. 11, No. 2, April 1982
·Willard, J.R. & H.H. Crowell. 1965. Biological Activities of the Harvester Ant, Pogonomyrmex owyheei, in Central Oregon. Journal of Economic Entomology Vol.58, No.3](http://www.pogolumina.net/NorthAmericanPogosbyBehavior/Plants/i-HJfmXT5/0/Ti/3319_10_7Dc-Ti.jpg "pogolumina > ● NW of Mattawa [Grant Co], WA USA [el. 152 m / 500 ft] view location in Google Maps »
● 5/9/10 10:14AM 50% cloud, air temp: 16°C / 61°F
[IMAGE 2 of 4] The seeds of western tansy-mustard (Descurainia sp.) are apparently a very important source of food for the Pogonomyrmex salinus ants of central Washington state. This series of four images was captured in the space of less than one minute - as a determined worker removed a relatively huge seed-pod from a living plant near her nest. Using her legs and gaster (large abdominal body part) to maximize leverage, she can be seen cutting through the stem, just below the seed-pod (1st and 2nd images). Suddenly, the pod is cut free, and the ant climbs out to the end of a seed-pod below, with cargo firmly held in her mandibles (3rd and 4th images). Two seconds after the last image, she dropped to the ground (from a height of about 25 cm / 10 inches) and ran at full speed to the nest, disappearing into the entrance with her prize.
ADDITIONAL NOTES/REFERENCES:
Descurainia (tansy-mustard) species thrive in dry (and often disturbed) soils, and are quite abundant in many areas where Pogos live. Nest middens are often full of empty Descurainia seed pods. We have observed and imaged P.salinus workers interacting with these plants in several locations in Washington state. These interactions encompass a range of behaviors, including the foraging of seeds/seed pods, removal of empty seed pods from nests, and the removal of entire plants from nest mounds and adjacent areas. Pogonomyrmex salinus has also been observed to collect the seeds/seed pods of various Descurainia species in Oregon and Idaho, and one study indicates that in central Oregon, Descurainia pinnata (western tansy-mustard) is one of the 5 most frequently collected seeds by P. salinus. The others were: Bromus tectorum, Phacelia linearis, Hordeum jubatum, and Sisymbrium altissimum.
·Jorgensen C.D. & Porter, S.D. 1982. Foraging Behavior of Pogonomyrmex owyheei in Southest Idaho. Environmental Entomology, Vol. 11, No. 2, April 1982
·Willard, J.R. & H.H. Crowell. 1965. Biological Activities of the Harvester Ant, Pogonomyrmex owyheei, in Central Oregon. Journal of Economic Entomology Vol.58, No.3")
![pogolumina > ● NW of Mattawa [Grant Co], WA USA [el. 152 m / 500 ft] view location in Google Maps »
● 5/9/10 10:14AM 50% cloud, air temp: 16°C / 61°F
[IMAGE 3 of 4] The seeds of western tansy-mustard (Descurainia sp.) are apparently a very important source of food for the Pogonomyrmex salinus ants of central Washington state. This series of four images was captured in the space of less than one minute - as a determined worker removed a relatively huge seed-pod from a living plant near her nest. Using her legs and gaster (large abdominal body part) to maximize leverage, she can be seen cutting through the stem, just below the seed-pod (1st and 2nd images). Suddenly, the pod is cut free, and the ant climbs out to the end of a seed-pod below, with cargo firmly held in her mandibles (3rd and 4th images). Two seconds after the last image, she dropped to the ground (from a height of about 25 cm / 10 inches) and ran at full speed to the nest, disappearing into the entrance with her prize.
ADDITIONAL NOTES/REFERENCES:
Descurainia (tansy-mustard) species thrive in dry (and often disturbed) soils, and are quite abundant in many areas where Pogos live. Nest middens are often full of empty Descurainia seed pods. We have observed and imaged P.salinus workers interacting with these plants in several locations in Washington state. These interactions encompass a range of behaviors, including the foraging of seeds/seed pods, removal of empty seed pods from nests, and the removal of entire plants from nest mounds and adjacent areas. Pogonomyrmex salinus has also been observed to collect the seeds/seed pods of various Descurainia species in Oregon and Idaho, and one study indicates that in central Oregon, Descurainia pinnata (western tansy-mustard) is one of the 5 most frequently collected seeds by P. salinus. The others were: Bromus tectorum, Phacelia linearis, Hordeum jubatum, and Sisymbrium altissimum.
·Jorgensen C.D. & Porter, S.D. 1982. Foraging Behavior of Pogonomyrmex owyheei in Southest Idaho. Environmental Entomology, Vol. 11, No. 2, April 1982
·Willard, J.R. & H.H. Crowell. 1965. Biological Activities of the Harvester Ant, Pogonomyrmex owyheei, in Central Oregon. Journal of Economic Entomology Vol.58, No.3](http://www.pogolumina.net/NorthAmericanPogosbyBehavior/Plants/i-DGLNJQS/0/Ti/3322_10_7Dc-Ti.jpg "pogolumina > ● NW of Mattawa [Grant Co], WA USA [el. 152 m / 500 ft] view location in Google Maps »
● 5/9/10 10:14AM 50% cloud, air temp: 16°C / 61°F
[IMAGE 3 of 4] The seeds of western tansy-mustard (Descurainia sp.) are apparently a very important source of food for the Pogonomyrmex salinus ants of central Washington state. This series of four images was captured in the space of less than one minute - as a determined worker removed a relatively huge seed-pod from a living plant near her nest. Using her legs and gaster (large abdominal body part) to maximize leverage, she can be seen cutting through the stem, just below the seed-pod (1st and 2nd images). Suddenly, the pod is cut free, and the ant climbs out to the end of a seed-pod below, with cargo firmly held in her mandibles (3rd and 4th images). Two seconds after the last image, she dropped to the ground (from a height of about 25 cm / 10 inches) and ran at full speed to the nest, disappearing into the entrance with her prize.
ADDITIONAL NOTES/REFERENCES:
Descurainia (tansy-mustard) species thrive in dry (and often disturbed) soils, and are quite abundant in many areas where Pogos live. Nest middens are often full of empty Descurainia seed pods. We have observed and imaged P.salinus workers interacting with these plants in several locations in Washington state. These interactions encompass a range of behaviors, including the foraging of seeds/seed pods, removal of empty seed pods from nests, and the removal of entire plants from nest mounds and adjacent areas. Pogonomyrmex salinus has also been observed to collect the seeds/seed pods of various Descurainia species in Oregon and Idaho, and one study indicates that in central Oregon, Descurainia pinnata (western tansy-mustard) is one of the 5 most frequently collected seeds by P. salinus. The others were: Bromus tectorum, Phacelia linearis, Hordeum jubatum, and Sisymbrium altissimum.
·Jorgensen C.D. & Porter, S.D. 1982. Foraging Behavior of Pogonomyrmex owyheei in Southest Idaho. Environmental Entomology, Vol. 11, No. 2, April 1982
·Willard, J.R. & H.H. Crowell. 1965. Biological Activities of the Harvester Ant, Pogonomyrmex owyheei, in Central Oregon. Journal of Economic Entomology Vol.58, No.3")
![pogolumina > ● NW of Mattawa [Grant Co], WA USA [el. 152 m / 500 ft] view location in Google Maps »
● 5/9/10 10:14AM 50% cloud, air temp: 16°C / 61°F
[IMAGE 4 of 4] The seeds of western tansy-mustard (Descurainia sp.) are apparently a very important source of food for the Pogonomyrmex salinus ants of central Washington state. This series of four images was captured in the space of less than one minute - as a determined worker removed a relatively huge seed-pod from a living plant near her nest. Using her legs and gaster (large abdominal body part) to maximize leverage, she can be seen cutting through the stem, just below the seed-pod (1st and 2nd images). Suddenly, the pod is cut free, and the ant climbs out to the end of a seed-pod below, with cargo firmly held in her mandibles (3rd and 4th images). Two seconds after the last image, she dropped to the ground (from a height of about 25 cm / 10 inches) and ran at full speed to the nest, disappearing into the entrance with her prize.
ADDITIONAL NOTES/REFERENCES:
Descurainia (tansy-mustard) species thrive in dry (and often disturbed) soils, and are quite abundant in many areas where Pogos live. Nest middens are often full of empty Descurainia seed pods. We have observed and imaged P.salinus workers interacting with these plants in several locations in Washington state. These interactions encompass a range of behaviors, including the foraging of seeds/seed pods, removal of empty seed pods from nests, and the removal of entire plants from nest mounds and adjacent areas. Pogonomyrmex salinus has also been observed to collect the seeds/seed pods of various Descurainia species in Oregon and Idaho, and one study indicates that in central Oregon, Descurainia pinnata (western tansy-mustard) is one of the 5 most frequently collected seeds by P. salinus. The others were: Bromus tectorum, Phacelia linearis, Hordeum jubatum, and Sisymbrium altissimum.
·Jorgensen C.D. & Porter, S.D. 1982. Foraging Behavior of Pogonomyrmex owyheei in Southest Idaho. Environmental Entomology, Vol. 11, No. 2, April 1982
·Willard, J.R. & H.H. Crowell. 1965. Biological Activities of the Harvester Ant, Pogonomyrmex owyheei, in Central Oregon. Journal of Economic Entomology Vol.58, No.3](http://www.pogolumina.net/NorthAmericanPogosbyBehavior/Plants/i-9SKShPn/0/Ti/3324_10_7Dc-Ti.jpg "pogolumina > ● NW of Mattawa [Grant Co], WA USA [el. 152 m / 500 ft] view location in Google Maps »
● 5/9/10 10:14AM 50% cloud, air temp: 16°C / 61°F
[IMAGE 4 of 4] The seeds of western tansy-mustard (Descurainia sp.) are apparently a very important source of food for the Pogonomyrmex salinus ants of central Washington state. This series of four images was captured in the space of less than one minute - as a determined worker removed a relatively huge seed-pod from a living plant near her nest. Using her legs and gaster (large abdominal body part) to maximize leverage, she can be seen cutting through the stem, just below the seed-pod (1st and 2nd images). Suddenly, the pod is cut free, and the ant climbs out to the end of a seed-pod below, with cargo firmly held in her mandibles (3rd and 4th images). Two seconds after the last image, she dropped to the ground (from a height of about 25 cm / 10 inches) and ran at full speed to the nest, disappearing into the entrance with her prize.
ADDITIONAL NOTES/REFERENCES:
Descurainia (tansy-mustard) species thrive in dry (and often disturbed) soils, and are quite abundant in many areas where Pogos live. Nest middens are often full of empty Descurainia seed pods. We have observed and imaged P.salinus workers interacting with these plants in several locations in Washington state. These interactions encompass a range of behaviors, including the foraging of seeds/seed pods, removal of empty seed pods from nests, and the removal of entire plants from nest mounds and adjacent areas. Pogonomyrmex salinus has also been observed to collect the seeds/seed pods of various Descurainia species in Oregon and Idaho, and one study indicates that in central Oregon, Descurainia pinnata (western tansy-mustard) is one of the 5 most frequently collected seeds by P. salinus. The others were: Bromus tectorum, Phacelia linearis, Hordeum jubatum, and Sisymbrium altissimum.
·Jorgensen C.D. & Porter, S.D. 1982. Foraging Behavior of Pogonomyrmex owyheei in Southest Idaho. Environmental Entomology, Vol. 11, No. 2, April 1982
·Willard, J.R. & H.H. Crowell. 1965. Biological Activities of the Harvester Ant, Pogonomyrmex owyheei, in Central Oregon. Journal of Economic Entomology Vol.58, No.3")
![pogolumina > ● Wanapum Rec. Area [Kittitas Co] WA, USA [el. 190 m / 623 ft] view location in Google Maps »
● 5/10/09 12:23PM sunny, air temp: 23°C / 74°F
A Pogonomyrmex salinus worker foraging on cheatgrass (Bromus tectorum) in central Washington state. [scroll down for additional notes/references]
ADDITIONAL NOTES/REFERENCES:
The introduced (and invasive) grass Bromus tectorum (cheatgrass), is common in many of the areas inhabited by Pogonomyrmex ants, and is often a target of their foraging activities.
One study in central Oregon found cheat grass (Bromus tectorum), to be one of the 5 most frequently collected seeds by P. salinus. The others were: Phacelia linearis, Hordeum jubatum, Descurainia pinnata, and Sisymbrium altissimum.
Pogonomyrmex occidentalis (a member of the same complex as P. salinus) has long been known to have an association with Bromus tectorum, though there are indications that this ant prefers other species when they are available. In the Twin Falls, Idaho area, Cole found the seeds of B. tectorum to be harvested in great quantities "...primarily due to the predominance of Bromus tectorum in the semi-desert areas." He also notes that "the seed chambers of mounds in dense bromegrass areas often contain a greater quantity of other seeds and only a few colonies were located which seemed to harvest bromegrass seeds exclusively."
This seems to be in keeping with the preliminary findings of a study of P. occidentalis in Colorado, by D. Wiernasz, where it was found that "Bromus tectorum was strongly avoided, and never exceeded 3% of seeds collected by foragers, even in high density areas."
·Cole, A.C. 1932a. The Relation of the Ant, Pogonomyrmex occidentalis CR., to its Habitat. Ohio Journal of Science, 32:133-46, Ohio State University
·Wiernasz, D. 2005. Granivore Activity on the Invasive Grass Bromus tectorum: a Factor in Establishment or Exclusion? University of Huston
·Willard, J.R. & H.H. Crowell. 1965. Biological Activities of the Harvester Ant, Pogonomyrmex owyheei, in Central Oregon. Journal of Economic Entomology Vol.58, No.3](http://www.pogolumina.net/NorthAmericanPogosbyBehavior/Plants/i-QJR5DHV/8/Ti/2088_09_Rf-Ti.jpg "pogolumina > ● Wanapum Rec. Area [Kittitas Co] WA, USA [el. 190 m / 623 ft] view location in Google Maps »
● 5/10/09 12:23PM sunny, air temp: 23°C / 74°F
A Pogonomyrmex salinus worker foraging on cheatgrass (Bromus tectorum) in central Washington state. [scroll down for additional notes/references]
ADDITIONAL NOTES/REFERENCES:
The introduced (and invasive) grass Bromus tectorum (cheatgrass), is common in many of the areas inhabited by Pogonomyrmex ants, and is often a target of their foraging activities.
One study in central Oregon found cheat grass (Bromus tectorum), to be one of the 5 most frequently collected seeds by P. salinus. The others were: Phacelia linearis, Hordeum jubatum, Descurainia pinnata, and Sisymbrium altissimum.
Pogonomyrmex occidentalis (a member of the same complex as P. salinus) has long been known to have an association with Bromus tectorum, though there are indications that this ant prefers other species when they are available. In the Twin Falls, Idaho area, Cole found the seeds of B. tectorum to be harvested in great quantities \"...primarily due to the predominance of Bromus tectorum in the semi-desert areas.\" He also notes that \"the seed chambers of mounds in dense bromegrass areas often contain a greater quantity of other seeds and only a few colonies were located which seemed to harvest bromegrass seeds exclusively.\"
This seems to be in keeping with the preliminary findings of a study of P. occidentalis in Colorado, by D. Wiernasz, where it was found that \"Bromus tectorum was strongly avoided, and never exceeded 3% of seeds collected by foragers, even in high density areas.\"
·Cole, A.C. 1932a. The Relation of the Ant, Pogonomyrmex occidentalis CR., to its Habitat. Ohio Journal of Science, 32:133-46, Ohio State University
·Wiernasz, D. 2005. Granivore Activity on the Invasive Grass Bromus tectorum: a Factor in Establishment or Exclusion? University of Huston
·Willard, J.R. & H.H. Crowell. 1965. Biological Activities of the Harvester Ant, Pogonomyrmex owyheei, in Central Oregon. Journal of Economic Entomology Vol.58, No.3")
![pogolumina > ● Fernley [Lyon Co], NV USA [el. 1271 m / 4171 ft] view location in Google Maps »
● 6/23/10 6:19AM partly cloudy, air temp: 17°C / 62°F
Finding a piece of plant matter, and picking it up with her mandibles - this Pogonomyrmex californicus worker heads back to the nest.](http://www.pogolumina.net/NorthAmericanPogosbyBehavior/Plants/i-9SgRjk4/0/Ti/4398_10_7Dc-Ti.jpg "pogolumina > ● Fernley [Lyon Co], NV USA [el. 1271 m / 4171 ft] view location in Google Maps »
● 6/23/10 6:19AM partly cloudy, air temp: 17°C / 62°F
Finding a piece of plant matter, and picking it up with her mandibles - this Pogonomyrmex californicus worker heads back to the nest.")
![pogolumina > ● Wanapum Rec. Area [Kittitas Co], WA USA [el. 190 m / 623 ft] view location in Google Maps »
● 6/4/09 8:00AM sunny, air temp: 23°C / 74°F
The stalk of this tiny flower (unidentified) had the tell-tale signs of having been gnawed on by Pogo mandibles. The flower itself had been about 40% chewed away, as well (by Pogos, or some other insect?). This Pogonomyrmex salinus worker appeared to be going over the petals with her mouthparts - possibly collecting nectar, or moisture. At one point, the ant attempted to cut through the stem, just below the flower - but to no avail.](http://www.pogolumina.net/NorthAmericanPogosbyBehavior/Plants/i-mjnjwCc/6/Ti/2485_09_Rc-Ti.jpg "pogolumina > ● Wanapum Rec. Area [Kittitas Co], WA USA [el. 190 m / 623 ft] view location in Google Maps »
● 6/4/09 8:00AM sunny, air temp: 23°C / 74°F
The stalk of this tiny flower (unidentified) had the tell-tale signs of having been gnawed on by Pogo mandibles. The flower itself had been about 40% chewed away, as well (by Pogos, or some other insect?). This Pogonomyrmex salinus worker appeared to be going over the petals with her mouthparts - possibly collecting nectar, or moisture. At one point, the ant attempted to cut through the stem, just below the flower - but to no avail.")
![pogolumina > ● SW of Pyramid Lake [Washoe Co], NV USA [el. 1323 m / 4341 ft] view location in Google Maps »
● 6/24/10 7:18AM mostly sunny, air temp: 16°C / 61°F
[IMAGE 1 of 4] About two dozen P.occidentalis workers started foraging along an approximately 4.5m / 15 ft long trunk trail [1], that extended from the nest in a northwesterly direction. Some of them began finding petals from saltbush plants (Atriplex sp.), and carrying them back to the nest from as far away as 3m / 10 feet. [scroll down for additional notes/references]
ADDITIONAL NOTES/REFERENCES:
Pogonomyrmex occidentalis, and P.salinus are generally regarded to be 'trunk-trail foragers'. In many cases, multiple, well established trails lead away from the nest in different directions. Workers travel along these paths to the end, and then disperse, or 'fan out' to search individually for seeds or other food items. After securing something (or in many cases failing to do so), the ants return individually to the nest by way of the trunk trail. In many Pogonomyrmex species, trunk-trails have been shown to be oriented so that foraging ants from neighboring colonies avoid mass confrontations during their searches for food. This allows there to be a greater density of nests in a given area, with minimal conflict.
These trails are initially established (and reinforced) by pheromones laid down by the ants. In at least one species (P. barbatus), foraging workers are influenced in their choice of which of multiple trails to utilize on a given day, by 'patrollers' - workers who leave the nest first in the morning, and scout the area. They then lay a short chemical trail with secretions from the Dufour's gland, from the nest entrance to the start of a particular trunk-trail(s). Evidence suggests that the direction chosen by the patrollers is not so much based on food availability, but by their encounters with patrollers from neighboring colonies.
The visibility and length of trunk-trails can vary greatly. The P.salinus trails we have observed so far (in Oregon and Washington states), while occasionally very visible (and free of vegetation), are more often indistinct, and not easily observable unless ants are traveling along them. As mentioned elsewhere on this site, we have observed trunk-trails of Pogonomyrmex salinus 9m / 29.5ft or more in length - though it is our experience that they are usually much shorter - and many nests (the majority in some locations) have no visible trails.
We also observe these ants foraging individually near the nest, in Oregon and Washington states.
·Greene, M.J. & D.M. Gordon. 2007. How Patrollers Set Foraging Direction in Harvester Ants. The American Naturalist, Vol. 170, No. 6, December 2007
·Hölldobler, B.1974. Home Range Orientation and Territoriality in Harvesting Ants. Proceedings of the National Academy of Sciences USA, Vol. 71, No. 8, pp. 3274-3277, August 1974
·Hölldobler, B. & E.O. Wilson.1990. The Ants. Cambridge, MA, Belknap/Harvard Press
·Johnson, R.A. 2000. Seed Harvesting Ants (Hymenoptera: Formicidae) of North America: An Overview of Ecology and Biogeography. Sociobiology Vol.36, No. 1, 2000
·Jorgensen C.D. & Porter, S.D. 1982. Foraging Behavior of Pogonomyrmex Owyheei in Southeast Idaho. Environmental Entomology, Vol. 11, No. 2, April 1982](http://www.pogolumina.net/NorthAmericanPogosbyBehavior/Plants/i-DhqXX2b/0/Ti/4564_10_7Dc-Ti.jpg "pogolumina > ● SW of Pyramid Lake [Washoe Co], NV USA [el. 1323 m / 4341 ft] view location in Google Maps »
● 6/24/10 7:18AM mostly sunny, air temp: 16°C / 61°F
[IMAGE 1 of 4] About two dozen P.occidentalis workers started foraging along an approximately 4.5m / 15 ft long trunk trail [1], that extended from the nest in a northwesterly direction. Some of them began finding petals from saltbush plants (Atriplex sp.), and carrying them back to the nest from as far away as 3m / 10 feet. [scroll down for additional notes/references]
ADDITIONAL NOTES/REFERENCES:
Pogonomyrmex occidentalis, and P.salinus are generally regarded to be 'trunk-trail foragers'. In many cases, multiple, well established trails lead away from the nest in different directions. Workers travel along these paths to the end, and then disperse, or 'fan out' to search individually for seeds or other food items. After securing something (or in many cases failing to do so), the ants return individually to the nest by way of the trunk trail. In many Pogonomyrmex species, trunk-trails have been shown to be oriented so that foraging ants from neighboring colonies avoid mass confrontations during their searches for food. This allows there to be a greater density of nests in a given area, with minimal conflict.
These trails are initially established (and reinforced) by pheromones laid down by the ants. In at least one species (P. barbatus), foraging workers are influenced in their choice of which of multiple trails to utilize on a given day, by 'patrollers' - workers who leave the nest first in the morning, and scout the area. They then lay a short chemical trail with secretions from the Dufour's gland, from the nest entrance to the start of a particular trunk-trail(s). Evidence suggests that the direction chosen by the patrollers is not so much based on food availability, but by their encounters with patrollers from neighboring colonies.
The visibility and length of trunk-trails can vary greatly. The P.salinus trails we have observed so far (in Oregon and Washington states), while occasionally very visible (and free of vegetation), are more often indistinct, and not easily observable unless ants are traveling along them. As mentioned elsewhere on this site, we have observed trunk-trails of Pogonomyrmex salinus 9m / 29.5ft or more in length - though it is our experience that they are usually much shorter - and many nests (the majority in some locations) have no visible trails.
We also observe these ants foraging individually near the nest, in Oregon and Washington states.
·Greene, M.J. & D.M. Gordon. 2007. How Patrollers Set Foraging Direction in Harvester Ants. The American Naturalist, Vol. 170, No. 6, December 2007
·Hölldobler, B.1974. Home Range Orientation and Territoriality in Harvesting Ants. Proceedings of the National Academy of Sciences USA, Vol. 71, No. 8, pp. 3274-3277, August 1974
·Hölldobler, B. & E.O. Wilson.1990. The Ants. Cambridge, MA, Belknap/Harvard Press
·Johnson, R.A. 2000. Seed Harvesting Ants (Hymenoptera: Formicidae) of North America: An Overview of Ecology and Biogeography. Sociobiology Vol.36, No. 1, 2000
·Jorgensen C.D. & Porter, S.D. 1982. Foraging Behavior of Pogonomyrmex Owyheei in Southeast Idaho. Environmental Entomology, Vol. 11, No. 2, April 1982")
![pogolumina > ● SW of Pyramid Lake [Washoe Co], NV USA [el. 1323 m / 4341 ft] view location in Google Maps »
● 6/24/10 7:36AM mostly sunny, air temp: 18°C / 64°F
[IMAGE 2 of 4] About two dozen P.occidentalis workers started foraging along an approximately 4.5m / 15 ft long trunk trail [1], that extended from the nest in a northwesterly direction. Some of them began finding petals from saltbush plants (Atriplex sp.), and carrying them back to the nest from as far away as 3m / 10 feet. [scroll down for additional notes/references]
ADDITIONAL NOTES/REFERENCES:
Pogonomyrmex occidentalis, and P.salinus are generally regarded to be 'trunk-trail foragers'. In many cases, multiple, well established trails lead away from the nest in different directions. Workers travel along these paths to the end, and then disperse, or 'fan out' to search individually for seeds or other food items. After securing something (or in many cases failing to do so), the ants return individually to the nest by way of the trunk trail. In many Pogonomyrmex species, trunk-trails have been shown to be oriented so that foraging ants from neighboring colonies avoid mass confrontations during their searches for food. This allows there to be a greater density of nests in a given area, with minimal conflict.
These trails are initially established (and reinforced) by pheromones laid down by the ants. In at least one species (P. barbatus), foraging workers are influenced in their choice of which of multiple trails to utilize on a given day, by 'patrollers' - workers who leave the nest first in the morning, and scout the area. They then lay a short chemical trail with secretions from the Dufour's gland, from the nest entrance to the start of a particular trunk-trail(s). Evidence suggests that the direction chosen by the patrollers is not so much based on food availability, but by their encounters with patrollers from neighboring colonies.
The visibility and length of trunk-trails can vary greatly. The P.salinus trails we have observed so far (in Oregon and Washington states), while occasionally very visible (and free of vegetation), are more often indistinct, and not easily observable unless ants are traveling along them. As mentioned elsewhere on this site, we have observed trunk-trails of Pogonomyrmex salinus 9m / 29.5ft or more in length - though it is our experience that they are usually much shorter - and many nests (the majority in some locations) have no visible trails.
We also observe these ants foraging individually near the nest, in Oregon and Washington states.
·Greene, M.J. & D.M. Gordon. 2007. How Patrollers Set Foraging Direction in Harvester Ants. The American Naturalist, Vol. 170, No. 6, December 2007
·Hölldobler, B.1974. Home Range Orientation and Territoriality in Harvesting Ants. Proceedings of the National Academy of Sciences USA, Vol. 71, No. 8, pp. 3274-3277, August 1974
·Hölldobler, B. & E.O. Wilson.1990. The Ants. Cambridge, MA, Belknap/Harvard Press
·Johnson, R.A. 2000. Seed Harvesting Ants (Hymenoptera: Formicidae) of North America: An Overview of Ecology and Biogeography. Sociobiology Vol.36, No. 1, 2000
·Jorgensen C.D. & Porter, S.D. 1982. Foraging Behavior of Pogonomyrmex Owyheei in Southeast Idaho. Environmental Entomology, Vol. 11, No. 2, April 1982](http://www.pogolumina.net/NorthAmericanPogosbyBehavior/Plants/i-cMrv3rr/0/Ti/4612_10_7Dc-Ti.jpg "pogolumina > ● SW of Pyramid Lake [Washoe Co], NV USA [el. 1323 m / 4341 ft] view location in Google Maps »
● 6/24/10 7:36AM mostly sunny, air temp: 18°C / 64°F
[IMAGE 2 of 4] About two dozen P.occidentalis workers started foraging along an approximately 4.5m / 15 ft long trunk trail [1], that extended from the nest in a northwesterly direction. Some of them began finding petals from saltbush plants (Atriplex sp.), and carrying them back to the nest from as far away as 3m / 10 feet. [scroll down for additional notes/references]
ADDITIONAL NOTES/REFERENCES:
Pogonomyrmex occidentalis, and P.salinus are generally regarded to be 'trunk-trail foragers'. In many cases, multiple, well established trails lead away from the nest in different directions. Workers travel along these paths to the end, and then disperse, or 'fan out' to search individually for seeds or other food items. After securing something (or in many cases failing to do so), the ants return individually to the nest by way of the trunk trail. In many Pogonomyrmex species, trunk-trails have been shown to be oriented so that foraging ants from neighboring colonies avoid mass confrontations during their searches for food. This allows there to be a greater density of nests in a given area, with minimal conflict.
These trails are initially established (and reinforced) by pheromones laid down by the ants. In at least one species (P. barbatus), foraging workers are influenced in their choice of which of multiple trails to utilize on a given day, by 'patrollers' - workers who leave the nest first in the morning, and scout the area. They then lay a short chemical trail with secretions from the Dufour's gland, from the nest entrance to the start of a particular trunk-trail(s). Evidence suggests that the direction chosen by the patrollers is not so much based on food availability, but by their encounters with patrollers from neighboring colonies.
The visibility and length of trunk-trails can vary greatly. The P.salinus trails we have observed so far (in Oregon and Washington states), while occasionally very visible (and free of vegetation), are more often indistinct, and not easily observable unless ants are traveling along them. As mentioned elsewhere on this site, we have observed trunk-trails of Pogonomyrmex salinus 9m / 29.5ft or more in length - though it is our experience that they are usually much shorter - and many nests (the majority in some locations) have no visible trails.
We also observe these ants foraging individually near the nest, in Oregon and Washington states.
·Greene, M.J. & D.M. Gordon. 2007. How Patrollers Set Foraging Direction in Harvester Ants. The American Naturalist, Vol. 170, No. 6, December 2007
·Hölldobler, B.1974. Home Range Orientation and Territoriality in Harvesting Ants. Proceedings of the National Academy of Sciences USA, Vol. 71, No. 8, pp. 3274-3277, August 1974
·Hölldobler, B. & E.O. Wilson.1990. The Ants. Cambridge, MA, Belknap/Harvard Press
·Johnson, R.A. 2000. Seed Harvesting Ants (Hymenoptera: Formicidae) of North America: An Overview of Ecology and Biogeography. Sociobiology Vol.36, No. 1, 2000
·Jorgensen C.D. & Porter, S.D. 1982. Foraging Behavior of Pogonomyrmex Owyheei in Southeast Idaho. Environmental Entomology, Vol. 11, No. 2, April 1982")
● Wanapum Rec. Area [Kittitas Co] WA, USA [el. 190 m / 623 ft] view location in Google Maps »
● 5/10/09 12:23PM sunny, air temp: 23°C / 74°F
![pogolumina > ● Wanapum Rec. Area [Kittitas Co] WA, USA [el. 190 m / 623 ft] view location in Google Maps »
● 5/10/09 12:23PM sunny, air temp: 23°C / 74°F
A Pogonomyrmex salinus worker foraging on cheatgrass (Bromus tectorum) in central Washington state. [scroll down for additional notes/references]
ADDITIONAL NOTES/REFERENCES:
The introduced (and invasive) grass Bromus tectorum (cheatgrass), is common in many of the areas inhabited by Pogonomyrmex ants, and is often a target of their foraging activities.
One study in central Oregon found cheat grass (Bromus tectorum), to be one of the 5 most frequently collected seeds by P. salinus. The others were: Phacelia linearis, Hordeum jubatum, Descurainia pinnata, and Sisymbrium altissimum.
Pogonomyrmex occidentalis (a member of the same complex as P. salinus) has long been known to have an association with Bromus tectorum, though there are indications that this ant prefers other species when they are available. In the Twin Falls, Idaho area, Cole found the seeds of B. tectorum to be harvested in great quantities "...primarily due to the predominance of Bromus tectorum in the semi-desert areas." He also notes that "the seed chambers of mounds in dense bromegrass areas often contain a greater quantity of other seeds and only a few colonies were located which seemed to harvest bromegrass seeds exclusively."
This seems to be in keeping with the preliminary findings of a study of P. occidentalis in Colorado, by D. Wiernasz, where it was found that "Bromus tectorum was strongly avoided, and never exceeded 3% of seeds collected by foragers, even in high density areas."
·Cole, A.C. 1932a. The Relation of the Ant, Pogonomyrmex occidentalis CR., to its Habitat. Ohio Journal of Science, 32:133-46, Ohio State University
·Wiernasz, D. 2005. Granivore Activity on the Invasive Grass Bromus tectorum: a Factor in Establishment or Exclusion? University of Huston
·Willard, J.R. & H.H. Crowell. 1965. Biological Activities of the Harvester Ant, Pogonomyrmex owyheei, in Central Oregon. Journal of Economic Entomology Vol.58, No.3](http://www.pogolumina.net/NorthAmericanPogosbyBehavior/Plants/i-QJR5DHV/8/M/2088_09_Rf-M.jpg "pogolumina > ● Wanapum Rec. Area [Kittitas Co] WA, USA [el. 190 m / 623 ft] view location in Google Maps »
● 5/10/09 12:23PM sunny, air temp: 23°C / 74°F
A Pogonomyrmex salinus worker foraging on cheatgrass (Bromus tectorum) in central Washington state. [scroll down for additional notes/references]
ADDITIONAL NOTES/REFERENCES:
The introduced (and invasive) grass Bromus tectorum (cheatgrass), is common in many of the areas inhabited by Pogonomyrmex ants, and is often a target of their foraging activities.
One study in central Oregon found cheat grass (Bromus tectorum), to be one of the 5 most frequently collected seeds by P. salinus. The others were: Phacelia linearis, Hordeum jubatum, Descurainia pinnata, and Sisymbrium altissimum.
Pogonomyrmex occidentalis (a member of the same complex as P. salinus) has long been known to have an association with Bromus tectorum, though there are indications that this ant prefers other species when they are available. In the Twin Falls, Idaho area, Cole found the seeds of B. tectorum to be harvested in great quantities \"...primarily due to the predominance of Bromus tectorum in the semi-desert areas.\" He also notes that \"the seed chambers of mounds in dense bromegrass areas often contain a greater quantity of other seeds and only a few colonies were located which seemed to harvest bromegrass seeds exclusively.\"
This seems to be in keeping with the preliminary findings of a study of P. occidentalis in Colorado, by D. Wiernasz, where it was found that \"Bromus tectorum was strongly avoided, and never exceeded 3% of seeds collected by foragers, even in high density areas.\"
·Cole, A.C. 1932a. The Relation of the Ant, Pogonomyrmex occidentalis CR., to its Habitat. Ohio Journal of Science, 32:133-46, Ohio State University
·Wiernasz, D. 2005. Granivore Activity on the Invasive Grass Bromus tectorum: a Factor in Establishment or Exclusion? University of Huston
·Willard, J.R. & H.H. Crowell. 1965. Biological Activities of the Harvester Ant, Pogonomyrmex owyheei, in Central Oregon. Journal of Economic Entomology Vol.58, No.3")
● 5/10/09 12:23PM sunny, air temp: 23°C / 74°F
A Pogonomyrmex salinus worker foraging on cheatgrass (Bromus tectorum) in central Washington state. [scroll down for additional notes/references]
ADDITIONAL NOTES/REFERENCES:
The introduced (and invasive) grass Bromus tectorum (cheatgrass), is common in many of the areas inhabited by Pogonomyrmex ants, and is often a target of their foraging activities.
One study in central Oregon found cheat grass (Bromus tectorum), to be one of the 5 most frequently collected seeds by P. salinus. The others were: Phacelia linearis, Hordeum jubatum, Descurainia pinnata, and Sisymbrium altissimum.
Pogonomyrmex occidentalis (a member of the same complex as P. salinus) has long been known to have an association with Bromus tectorum, though there are indications that this ant prefers other species when they are available. In the Twin Falls, Idaho area, Cole found the seeds of B. tectorum to be harvested in great quantities "...primarily due to the predominance of Bromus tectorum in the semi-desert areas." He also notes that "the seed chambers of mounds in dense bromegrass areas often contain a greater quantity of other seeds and only a few colonies were located which seemed to harvest bromegrass seeds exclusively."
This seems to be in keeping with the preliminary findings of a study of P. occidentalis in Colorado, by D. Wiernasz, where it was found that "Bromus tectorum was strongly avoided, and never exceeded 3% of seeds collected by foragers, even in high density areas."
·Cole, A.C. 1932a. The Relation of the Ant, Pogonomyrmex occidentalis CR., to its Habitat. Ohio Journal of Science, 32:133-46, Ohio State University
·Wiernasz, D. 2005. Granivore Activity on the Invasive Grass Bromus tectorum: a Factor in Establishment or Exclusion? University of Huston
·Willard, J.R. & H.H. Crowell. 1965. Biological Activities of the Harvester Ant, Pogonomyrmex owyheei, in Central Oregon. Journal of Economic Entomology Vol.58, No.3
The introduced (and invasive) grass Bromus tectorum (cheatgrass), is common in many of the areas inhabited by Pogonomyrmex ants, and is often a target of their foraging activities.
One study in central Oregon found cheat grass (Bromus tectorum), to be one of the 5 most frequently collected seeds by P. salinus. The others were: Phacelia linearis, Hordeum jubatum, Descurainia pinnata, and Sisymbrium altissimum.
Pogonomyrmex occidentalis (a member of the same complex as P. salinus) has long been known to have an association with Bromus tectorum, though there are indications that this ant prefers other species when they are available. In the Twin Falls, Idaho area, Cole found the seeds of B. tectorum to be harvested in great quantities "...primarily due to the predominance of Bromus tectorum in the semi-desert areas." He also notes that "the seed chambers of mounds in dense bromegrass areas often contain a greater quantity of other seeds and only a few colonies were located which seemed to harvest bromegrass seeds exclusively."
This seems to be in keeping with the preliminary findings of a study of P. occidentalis in Colorado, by D. Wiernasz, where it was found that "Bromus tectorum was strongly avoided, and never exceeded 3% of seeds collected by foragers, even in high density areas."
·Cole, A.C. 1932a. The Relation of the Ant, Pogonomyrmex occidentalis CR., to its Habitat. Ohio Journal of Science, 32:133-46, Ohio State University
·Wiernasz, D. 2005. Granivore Activity on the Invasive Grass Bromus tectorum: a Factor in Establishment or Exclusion? University of Huston
·Willard, J.R. & H.H. Crowell. 1965. Biological Activities of the Harvester Ant, Pogonomyrmex owyheei, in Central Oregon. Journal of Economic Entomology Vol.58, No.3
● Wanapum Rec. Area [Kittitas Co] WA, USA [el. 190 m / 623 ft] view location in Google Maps »
● 5/10/09 12:23PM sunny, air temp: 23°C / 74°F
● 5/10/09 12:23PM sunny, air temp: 23°C / 74°F
A Pogonomyrmex salinus worker foraging on cheatgrass (Bromus tectorum) in central Washington state. [scroll down for additional notes/references]
ADDITIONAL NOTES/REFERENCES:
The introduced (and invasive) grass Bromus tectorum (cheatgrass), is common in many of the areas inhabited by Pogonomyrmex ants, and is often a target of their foraging activities.
One study in central Oregon found cheat grass (Bromus tectorum), to be one of the 5 most frequently collected seeds by P. salinus. The others were: Phacelia linearis, Hordeum jubatum, Descurainia pinnata, and Sisymbrium altissimum.
Pogonomyrmex occidentalis (a member of the same complex as P. salinus) has long been known to have an association with Bromus tectorum, though there are indications that this ant prefers other species when they are available. In the Twin Falls, Idaho area, Cole found the seeds of B. tectorum to be harvested in great quantities "...primarily due to the predominance of Bromus tectorum in the semi-desert areas." He also notes that "the seed chambers of mounds in dense bromegrass areas often contain a greater quantity of other seeds and only a few colonies were located which seemed to harvest bromegrass seeds exclusively."
This seems to be in keeping with the preliminary findings of a study of P. occidentalis in Colorado, by D. Wiernasz, where it was found that "Bromus tectorum was strongly avoided, and never exceeded 3% of seeds collected by foragers, even in high density areas."
·Cole, A.C. 1932a. The Relation of the Ant, Pogonomyrmex occidentalis CR., to its Habitat. Ohio Journal of Science, 32:133-46, Ohio State University
·Wiernasz, D. 2005. Granivore Activity on the Invasive Grass Bromus tectorum: a Factor in Establishment or Exclusion? University of Huston
·Willard, J.R. & H.H. Crowell. 1965. Biological Activities of the Harvester Ant, Pogonomyrmex owyheei, in Central Oregon. Journal of Economic Entomology Vol.58, No.3
The introduced (and invasive) grass Bromus tectorum (cheatgrass), is common in many of the areas inhabited by Pogonomyrmex ants, and is often a target of their foraging activities.
One study in central Oregon found cheat grass (Bromus tectorum), to be one of the 5 most frequently collected seeds by P. salinus. The others were: Phacelia linearis, Hordeum jubatum, Descurainia pinnata, and Sisymbrium altissimum.
Pogonomyrmex occidentalis (a member of the same complex as P. salinus) has long been known to have an association with Bromus tectorum, though there are indications that this ant prefers other species when they are available. In the Twin Falls, Idaho area, Cole found the seeds of B. tectorum to be harvested in great quantities "...primarily due to the predominance of Bromus tectorum in the semi-desert areas." He also notes that "the seed chambers of mounds in dense bromegrass areas often contain a greater quantity of other seeds and only a few colonies were located which seemed to harvest bromegrass seeds exclusively."
This seems to be in keeping with the preliminary findings of a study of P. occidentalis in Colorado, by D. Wiernasz, where it was found that "Bromus tectorum was strongly avoided, and never exceeded 3% of seeds collected by foragers, even in high density areas."
·Cole, A.C. 1932a. The Relation of the Ant, Pogonomyrmex occidentalis CR., to its Habitat. Ohio Journal of Science, 32:133-46, Ohio State University
·Wiernasz, D. 2005. Granivore Activity on the Invasive Grass Bromus tectorum: a Factor in Establishment or Exclusion? University of Huston
·Willard, J.R. & H.H. Crowell. 1965. Biological Activities of the Harvester Ant, Pogonomyrmex owyheei, in Central Oregon. Journal of Economic Entomology Vol.58, No.3
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