Interactions with Plants
From seed foraging to plant removal. Pogos
interacting with the plant life around them, in North America.
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![<span class="captionImageInfo"> ● Wanapum Rec. Area [Kittitas Co], WA USA [el. 190 m / 623 ft]</span> <a href="http://maps.google.com/maps/ms?ie=UTF8&hl=en&t=h&msa=0&msid=100103460138962878270.000470bd413e9e793ba1d&ll=46.905483,-119.9903&spn=0.164191,0.291824&z=11&source=embed"><span class="mapLink">view location in Google Maps »</span></a>
<span class="captionImageInfo"> ● 6/4/09 8:00AM sunny, air temp: 23°C / 74°F</span>
<div class="captionImageMain">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 <a href="http://www.davidlouisquinn.com/pogolumina_PsalinusInfo.htm"><span class="glossLinkSm"><em>Pogonomyrmex salinus</em></span></a> worker appeared to be going over the petals with her mouthparts - possibly <a href="http://www.davidlouisquinn.com/pogolumina_feedingInfo.htm"><span class="glossLinkSm">collecting nectar</span></a>, or moisture. At one point, the ant attempted to cut through the stem, just below the flower - but to no avail.</div>](https://photos.smugmug.com/NorthAmericanPogosbyBehavior/Plants/i-mjnjwCc/6/7845a1a5/L/2485_09_Rc-L.jpg)
● 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.
pogopogonomyrmexpogonomyrmex salinusants interacting with plantsmacroharvester ants
![<span class="captionImageInfo"> ● NW of Mattawa [Grant Co], WA USA [el. 152 m / 500 ft]</span> <a href="http://maps.google.com/maps/ms?ie=UTF8&hl=en&t=h&msa=0&msid=100103460138962878270.000470f37e319b015bf28&ll=46.7596,-119.932433&spn=0.329276,0.583649&z=10&source=embed"><span class="mapLink"> view location in Google Maps »</span></a>
<span class="captionImageInfo"> ● 5/9/10 12:15PM sunny, air temp: [not measured]</span>
<div class="captionImageMain">Silhouetted against the bright background, this <a href="http://www.davidlouisquinn.com/pogolumina_PsalinusInfo.htm"><span class="glossLinkSm"><em>P. salinus</em></span></a> worker searches a fiddleneck plant (<em>Amsinckia</em> sp.) for <a href="http://www.davidlouisquinn.com/pogolumina_feedingInfo.htm"><span class="glossLinkSm">nectar</span></a>, in central Washington state. </div>](https://photos.smugmug.com/NorthAmericanPogosbyBehavior/Plants/i-rtn3jN7/0/99aa97b2/Ti/3360_10_7Df-Ti.jpg)
![<span class="captionImageInfo"> ● Wanapum Rec. Area [Kittitas Co], WA USA [el. 190 m / 623 ft]</span> <a href="http://maps.google.com/maps/ms?ie=UTF8&hl=en&t=h&msa=0&msid=100103460138962878270.000470bd413e9e793ba1d&ll=46.905483,-119.9903&spn=0.164191,0.291824&z=11&source=embed"><span class="mapLink">view location in Google Maps »</span></a>
<span class="captionImageInfo"> ● 4/19/10 11:01AM sun, haze, air temp: 22°C / 72°F</span>
<div class="captionImageMain">[IMAGE 1 of 4 - same description for these 4 images] Spring is a busy time for <a href="http://www.davidlouisquinn.com/pogolumina_PsalinusInfo.htm"><span class="glossLinkSm"><em>Pogonomyrmex salinus</em></span></a> <a href="http://www.davidlouisquinn.com/pogolumina_workerInfo.htm"><span class="glossLinkSm">workers</span></a>. While some colony members forage, or conduct maintenance on the nest below, others engage in the <a href="http://www.davidlouisquinn.com/pogolumina_nestClearingInfo.htm"><span class="glossLinkSm">removal of plants</span></a> that have sprung up on, or too close to the nest mound. Even with their powerful <a href="http://www.davidlouisquinn.com/pogolumina_mandiblesInfo.htm"><span class="glossLinkSm">mandibles</span></a>, 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 (<em>Bromus tectorum</em>) growing on, and around the edges of the nest mound <a href="http://www.davidlouisquinn.com/pogolumina_grass_cutting01Info.htm"><span class="glossLinkSm">[see additional images » ]</span></a>. 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. <span class ="footnoteTag">[scroll down for additional notes/references]</span>
</div>
<div class="captionRefFootnote">ADDITIONAL NOTES/REFERENCES:
<em>
The introduced (and invasive) grass Bromus tectorum (cheatgrass), is common in many of the areas inhabited by <a href="http://www.davidlouisquinn.com/pogolumina_PogonomyrmexInfo.htm"><span class="glossLinkSm"><em>Pogonomyrmex</em></span></a> 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.
<a href="http://www.davidlouisquinn.com/pogolumina_PoccidentalisInfo.htm"><span class="glossLinkSm">Pogonomyrmex occidentalis</span></a> (a member of the same complex as P. salinus) has long been known to have an association with <em>Bromus tectorum</em>, 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
</em></div>](https://photos.smugmug.com/NorthAmericanPogosbyBehavior/Plants/i-Tw8SZnL/1/370456a4/Ti/2860_10_7Df-Ti.jpg)
![<span class="captionImageInfo"> ● Wanapum Rec. Area [Kittitas Co], WA USA [el. 190 m / 623 ft]</span> <a href="http://maps.google.com/maps/ms?ie=UTF8&hl=en&t=h&msa=0&msid=100103460138962878270.000470bd413e9e793ba1d&ll=46.905483,-119.9903&spn=0.164191,0.291824&z=11&source=embed"><span class="mapLink">view location in Google Maps »</span></a>
<span class="captionImageInfo"> ● 4/19/10 12:17PM sun, haze, air temp: 25°C / 77°F</span>
<div class="captionImageMain">[IMAGE 2 of 4 - same description for these 4 images] Spring is a busy time for <a href="http://www.davidlouisquinn.com/pogolumina_PsalinusInfo.htm"><span class="glossLinkSm"><em>Pogonomyrmex salinus</em></span></a> <a href="http://www.davidlouisquinn.com/pogolumina_workerInfo.htm"><span class="glossLinkSm">workers</span></a>. While some colony members forage, or conduct maintenance on the nest below, others engage in the <a href="http://www.davidlouisquinn.com/pogolumina_nestClearingInfo.htm"><span class="glossLinkSm">removal of plants</span></a> that have sprung up on, or too close to the nest mound. Even with their powerful <a href="http://www.davidlouisquinn.com/pogolumina_mandiblesInfo.htm"><span class="glossLinkSm">mandibles</span></a>, 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 (<em>Bromus tectorum</em>) growing on, and around the edges of the nest mound <a href="http://www.davidlouisquinn.com/pogolumina_grass_cutting01Info.htm"><span class="glossLinkSm">[see additional images » ]</span></a>. 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. <span class ="footnoteTag">[scroll down for additional notes/references]</span>
</div>
<div class="captionRefFootnote">ADDITIONAL NOTES/REFERENCES:
<em>
The introduced (and invasive) grass Bromus tectorum (cheatgrass), is common in many of the areas inhabited by <a href="http://www.davidlouisquinn.com/pogolumina_PogonomyrmexInfo.htm"><span class="glossLinkSm"><em>Pogonomyrmex</em></span></a> 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.
<a href="http://www.davidlouisquinn.com/pogolumina_PoccidentalisInfo.htm"><span class="glossLinkSm">
Pogonomyrmex occidentalis </span></a> (a member of the same complex as P. salinus) has long been known to have an association with <em>Bromus tectorum</em>, 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
</em></div>](https://photos.smugmug.com/NorthAmericanPogosbyBehavior/Plants/i-qkMc9MT/3/b6ccb858/Ti/2905_10_7Dc-Ti.jpg)
![<span class="captionImageInfo"> ● Wanapum Rec. Area [Kittitas Co], WA USA [el. 190 m / 623 ft]</span> <a href="http://maps.google.com/maps/ms?ie=UTF8&hl=en&t=h&msa=0&msid=100103460138962878270.000470bd413e9e793ba1d&ll=46.905483,-119.9903&spn=0.164191,0.291824&z=11&source=embed"><span class="mapLink">view location in Google Maps »</span></a>
<span class="captionImageInfo"> ● 4/19/10 12:31PM sun, haze, air temp: 25°C / 77°F</span>
<div class="captionImageMain">[IMAGE 3 of 4 - same description for these 4 images] Spring is a busy time for <a href="http://www.davidlouisquinn.com/pogolumina_PsalinusInfo.htm"><span class="glossLinkSm"><em>Pogonomyrmex salinus</em></span></a> <a href="http://www.davidlouisquinn.com/pogolumina_workerInfo.htm"><span class="glossLinkSm">workers</span></a>. While some colony members forage, or conduct maintenance on the nest below, others engage in the <a href="http://www.davidlouisquinn.com/pogolumina_nestClearingInfo.htm"><span class="glossLinkSm">removal of plants</span></a> that have sprung up on, or too close to the nest mound. Even with their powerful <a href="http://www.davidlouisquinn.com/pogolumina_mandiblesInfo.htm"><span class="glossLinkSm">mandibles</span></a>, 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 (<em>Bromus tectorum</em>) growing on, and around the edges of the nest mound <a href="http://www.davidlouisquinn.com/pogolumina_grass_cutting01Info.htm"><span class="glossLinkSm">[see additional images » ]</span></a>. 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. <span class ="footnoteTag">[scroll down for additional notes/references]</span>
</div>
<div class="captionRefFootnote">ADDITIONAL NOTES/REFERENCES:
<em>
The introduced (and invasive) grass Bromus tectorum (cheatgrass), is common in many of the areas inhabited by <a href="http://www.davidlouisquinn.com/pogolumina_PogonomyrmexInfo.htm"><span class="glossLinkSm"><em>Pogonomyrmex</em></span></a> 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.
<a href="http://www.davidlouisquinn.com/pogolumina_PoccidentalisInfo.htm"><span class="glossLinkSm">Pogonomyrmex occidentalis </span></a> (a member of the same complex as P. salinus) has long been known to have an association with <em>Bromus tectorum</em>, 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
</em></div>](https://photos.smugmug.com/NorthAmericanPogosbyBehavior/Plants/i-J2rbtMC/4/14347740/Ti/2943_10_7Df-Ti.jpg)
![<span class="captionImageInfo"> ● Wanapum Rec. Area [Kittitas Co], WA USA [el. 190 m / 623 ft]</span> <a href="http://maps.google.com/maps/ms?ie=UTF8&hl=en&t=h&msa=0&msid=100103460138962878270.000470bd413e9e793ba1d&ll=46.905483,-119.9903&spn=0.164191,0.291824&z=11&source=embed"><span class="mapLink">view location in Google Maps »</span></a>
<span class="captionImageInfo"> ● 4/19/10 1:14PM sun, haze, air temp: 26°C / 79°F</span>
<div class="captionImageMain">[IMAGE 4 of 4 - same description for these 4 images] Spring is a busy time for <a href="http://www.davidlouisquinn.com/pogolumina_PsalinusInfo.htm"><span class="glossLinkSm"><em>Pogonomyrmex salinus</em></span></a> <a href="http://www.davidlouisquinn.com/pogolumina_workerInfo.htm"><span class="glossLinkSm">workers</span></a>. While some colony members forage, or conduct maintenance on the nest below, others engage in the <a href="http://www.davidlouisquinn.com/pogolumina_nestClearingInfo.htm"><span class="glossLinkSm">removal of plants</span></a> that have sprung up on, or too close to the nest mound. Even with their powerful <a href="http://www.davidlouisquinn.com/pogolumina_mandiblesInfo.htm"><span class="glossLinkSm">mandibles</span></a>, 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 (<em>Bromus tectorum</em>) growing on, and around the edges of the nest mound <a href="http://www.davidlouisquinn.com/pogolumina_grass_cutting01Info.htm"><span class="glossLinkSm">[see additional images » ]</span></a>. 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. <span class ="footnoteTag">[scroll down for additional notes/references]</span>
</div>
<div class="captionRefFootnote">ADDITIONAL NOTES/REFERENCES:
<em>
The introduced (and invasive) grass Bromus tectorum (cheatgrass), is common in many of the areas inhabited by <a href="http://www.davidlouisquinn.com/pogolumina_PogonomyrmexInfo.htm"><span class="glossLinkSm"><em>Pogonomyrmex</em></span></a> 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.
<a href="http://www.davidlouisquinn.com/pogolumina_PoccidentalisInfo.htm"><span class="glossLinkSm">Pogonomyrmex occidentalis</span></a> (a member of the same complex as P. salinus) has long been known to have an association with <em>Bromus tectorum</em>, 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
</em></div>](https://photos.smugmug.com/NorthAmericanPogosbyBehavior/Plants/i-DTBFXKV/0/8887f450/Ti/3005_10_7Dc-Ti.jpg)
![<span class="captionImageInfo"> ● Castolon [Loc 41] Big Bend N.P., TX USA [el. 660 m / 2164 ft]</span> <a href="http://maps.google.com/maps/ms?ie=UTF8&hl=en&t=h&msa=0&msid=100103460138962878270.00048384c67ef9deb4b45&ll=29.13417,-103.513355&spn=0.05248,0.072956&z=13&source=embed"><span class="mapLink"> view location in Google Maps »<span></a>
<span class="captionImageInfo"> ● 3/06/10 10:27AM sun/haze, air temp: 18°C / 64°F</span>
<div class="captionImageMain">Though too early in the season for new <a href="http://www.davidlouisquinn.com/pogolumina_feedingInfo.htm"><span class="glossLinkSm">seeds</span></a> to be available (at this location), these <a href="http://www.davidlouisquinn.com/pogolumina_PdesertorumInfo.htm"><span class="glossLinkSm"><em>P. desertorum</em></span></a> 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. <span class ="footnoteTag">[scroll down for additional notes/references]</span>
</div>
<div class="captionRefFootnote">ADDITIONAL NOTES/REFERENCES:
<em>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.</em>
</div>](https://photos.smugmug.com/NorthAmericanPogosbyBehavior/Plants/i-9cRGRLs/7/11630bdc/Ti/IMG_2176_10_7Df-Ti.jpg)
![<span class="captionImageInfo"> ● NW of Mattawa [Grant Co], WA USA [el. 152 m / 500 ft]</span> <a href="http://maps.google.com/maps/ms?ie=UTF8&hl=en&t=h&msa=0&msid=100103460138962878270.000470f37e319b015bf28&ll=46.7596,-119.932433&spn=0.329276,0.583649&z=10&source=embed"><span class="mapLink"> view location in Google Maps »</span></a>
<span class="captionImageInfo"> ● 5/9/10 10:14AM 50% cloud, air temp: 16°C / 61°F</span>
<div class="captionImageMain">[IMAGE 1 of 4] The seeds of western tansy-mustard (<em>Descurainia sp.</em>) are apparently a very important <a href="http://www.davidlouisquinn.com/pogolumina_feedingInfo.htm"><span class="glossLinkSm">source of food</span></a> for the <a href="http://www.davidlouisquinn.com/pogolumina_PsalinusInfo.htm"><span class="glossLinkSm"><em>Pogonomyrmex salinus</em></span></a> 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 <a href="http://www.davidlouisquinn.com/pogolumina_mandiblesInfo.htm"><span class="glossLinkSm">mandibles</span></a> (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.</div>
<div class="captionRefFootnote">ADDITIONAL NOTES/REFERENCES:
<em>Descurainia (tansy-mustard) species thrive in dry (and often disturbed) soils, and are quite abundant in many areas where Pogos live. <a href="http://www.davidlouisquinn.com/pogolumina_chaffInfo.htm"><span class="glossLinkSm">Nest middens</span></a> 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 <a href="http://www.davidlouisquinn.com/pogolumina_nestClearingInfo.htm"><span class="glossLinkSm">removal of entire plants</span></a> 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</em></div>](https://photos.smugmug.com/NorthAmericanPogosbyBehavior/Plants/i-2qCRHc4/2/43cfcd97/Ti/3317_10_7Df-Ti.jpg)
![<span class="captionImageInfo"> ● NW of Mattawa [Grant Co], WA USA [el. 152 m / 500 ft]</span> <a href="http://maps.google.com/maps/ms?ie=UTF8&hl=en&t=h&msa=0&msid=100103460138962878270.000470f37e319b015bf28&ll=46.7596,-119.932433&spn=0.329276,0.583649&z=10&source=embed"><span class="mapLink"> view location in Google Maps »</span></a>
<span class="captionImageInfo"> ● 5/9/10 10:14AM 50% cloud, air temp: 16°C / 61°F</span>
<div class="captionImageMain">[IMAGE 2 of 4] The seeds of western tansy-mustard (<em>Descurainia sp.</em>) are apparently a very important <a href="http://www.davidlouisquinn.com/pogolumina_feedingInfo.htm"><span class="glossLinkSm">source of food</span></a> for the <a href="http://www.davidlouisquinn.com/pogolumina_PsalinusInfo.htm"><span class="glossLinkSm"><em>Pogonomyrmex salinus</em></span></a> 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 <a href="http://www.davidlouisquinn.com/pogolumina_mandiblesInfo.htm"><span class="glossLinkSm">mandibles</span></a> (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.</div>
<div class="captionRefFootnote">ADDITIONAL NOTES/REFERENCES:
<em>Descurainia (tansy-mustard) species thrive in dry (and often disturbed) soils, and are quite abundant in many areas where Pogos live. <a href="http://www.davidlouisquinn.com/pogolumina_chaffInfo.htm"><span class="glossLinkSm">Nest middens</span></a> 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 <a href="http://www.davidlouisquinn.com/pogolumina_nestClearingInfo.htm"><span class="glossLinkSm">removal of entire plants</span></a> 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</em></div>](https://photos.smugmug.com/NorthAmericanPogosbyBehavior/Plants/i-HJfmXT5/0/9b04d45f/Ti/3319_10_7Dc-Ti.jpg)
![<span class="captionImageInfo"> ● NW of Mattawa [Grant Co], WA USA [el. 152 m / 500 ft]</span> <a href="http://maps.google.com/maps/ms?ie=UTF8&hl=en&t=h&msa=0&msid=100103460138962878270.000470f37e319b015bf28&ll=46.7596,-119.932433&spn=0.329276,0.583649&z=10&source=embed"><span class="mapLink"> view location in Google Maps »</span></a>
<span class="captionImageInfo"> ● 5/9/10 10:14AM 50% cloud, air temp: 16°C / 61°F</span>
<div class="captionImageMain">[IMAGE 3 of 4] The seeds of western tansy-mustard (<em>Descurainia sp.</em>) are apparently a very important <a href="http://www.davidlouisquinn.com/pogolumina_feedingInfo.htm"><span class="glossLinkSm">source of food</span></a> for the <a href="http://www.davidlouisquinn.com/pogolumina_PsalinusInfo.htm"><span class="glossLinkSm"><em>Pogonomyrmex salinus</em></span></a> 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 <a href="http://www.davidlouisquinn.com/pogolumina_mandiblesInfo.htm"><span class="glossLinkSm">mandibles</span></a> (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.</div>
<div class="captionRefFootnote">ADDITIONAL NOTES/REFERENCES:
<em>Descurainia (tansy-mustard) species thrive in dry (and often disturbed) soils, and are quite abundant in many areas where Pogos live. <a href="http://www.davidlouisquinn.com/pogolumina_chaffInfo.htm"><span class="glossLinkSm">Nest middens</span></a> 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 <a href="http://www.davidlouisquinn.com/pogolumina_nestClearingInfo.htm"><span class="glossLinkSm">removal of entire plants</span></a> 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</em></div>](https://photos.smugmug.com/NorthAmericanPogosbyBehavior/Plants/i-DGLNJQS/0/945cd595/Ti/3322_10_7Dc-Ti.jpg)
![<span class="captionImageInfo"> ● NW of Mattawa [Grant Co], WA USA [el. 152 m / 500 ft]</span> <a href="http://maps.google.com/maps/ms?ie=UTF8&hl=en&t=h&msa=0&msid=100103460138962878270.000470f37e319b015bf28&ll=46.7596,-119.932433&spn=0.329276,0.583649&z=10&source=embed"><span class="mapLink"> view location in Google Maps »</span></a>
<span class="captionImageInfo"> ● 5/9/10 10:14AM 50% cloud, air temp: 16°C / 61°F</span>
<div class="captionImageMain">[IMAGE 4 of 4] The seeds of western tansy-mustard (<em>Descurainia sp.</em>) are apparently a very important <a href="http://www.davidlouisquinn.com/pogolumina_feedingInfo.htm"><span class="glossLinkSm">source of food</span></a> for the <a href="http://www.davidlouisquinn.com/pogolumina_PsalinusInfo.htm"><span class="glossLinkSm"><em>Pogonomyrmex salinus</em></span></a> 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 <a href="http://www.davidlouisquinn.com/pogolumina_mandiblesInfo.htm"><span class="glossLinkSm">mandibles</span></a> (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.</div>
<div class="captionRefFootnote">ADDITIONAL NOTES/REFERENCES:
<em>Descurainia (tansy-mustard) species thrive in dry (and often disturbed) soils, and are quite abundant in many areas where Pogos live. <a href="http://www.davidlouisquinn.com/pogolumina_chaffInfo.htm"><span class="glossLinkSm">Nest middens</span></a> 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 <a href="http://www.davidlouisquinn.com/pogolumina_nestClearingInfo.htm"><span class="glossLinkSm">removal of entire plants</span></a> 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</em></div>](https://photos.smugmug.com/NorthAmericanPogosbyBehavior/Plants/i-9SKShPn/0/21f89c96/Ti/3324_10_7Dc-Ti.jpg)
![<span class="captionImageInfo"> ● Wanapum Rec. Area [Kittitas Co] WA, USA [el. 190 m / 623 ft]</span> <a href="http://maps.google.com/maps/ms?ie=UTF8&hl=en&t=h&msa=0&msid=100103460138962878270.000470bd413e9e793ba1d&ll=46.905483,-119.9903&spn=0.164191,0.291824&z=11&source=embed"><span class="mapLink">view location in Google Maps »</span></a>
<span class="captionImageInfo"> ● 5/10/09 12:23PM sunny, air temp: 23°C / 74°F</span>
<div class="captionImageMain"> A <a href="http://www.davidlouisquinn.com/pogolumina_PsalinusInfo.htm"><span class="glossLinkSm"><em>Pogonomyrmex salinus</em></span></a> worker <a href="http://www.davidlouisquinn.com/pogolumina_feedingInfo.htm"><span class="glossLinkSm">foraging</span></a> on cheatgrass (<em>Bromus tectorum)</em> in central Washington state. <span class ="footnoteTag">[scroll down for additional notes/references]</span>
<div class="captionRefFootnote">ADDITIONAL NOTES/REFERENCES:
<em>
The introduced (and invasive) grass Bromus tectorum (cheatgrass), is common in many of the areas inhabited by <a href="http://www.davidlouisquinn.com/pogolumina_PogonomyrmexInfo.htm"><span class="glossLinkSm"><em>Pogonomyrmex</em></span></a> 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.
<a href="http://www.davidlouisquinn.com/pogolumina_PoccidentalisInfo.htm"><span class="glossLinkSm">Pogonomyrmex occidentalis</span></a> (a member of the same complex as P. salinus) has long been known to have an association with <em>Bromus tectorum</em>, 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
</em></div>](https://photos.smugmug.com/NorthAmericanPogosbyBehavior/Plants/i-QJR5DHV/8/9f4c4470/Ti/2088_09_Rf-Ti.jpg)
![<span class="captionImageInfo"> ● Fernley [Lyon Co], NV USA [el. 1271 m / 4171 ft]</span> <a href="http://maps.google.com/maps/ms?ie=UTF8&hl=en&t=h&msa=0&msid=100103460138962878270.00048afd64f5e81bc4956&ll=39.614152,-119.262085&spn=1.481079,2.334595&z=8&source=embed"><span class="mapLink">view location in Google Maps »</span></a>
<span class="captionImageInfo"> ● 6/23/10 6:19AM partly cloudy, air temp: 17°C / 62°F</span>
<div class="captionImageMain">Finding a piece of plant matter, and picking it up with her <a href="http://www.davidlouisquinn.com/pogolumina_mandiblesInfo.htm"><span class="glossLinkSm">mandibles</span></a> - this <a href="http://www.davidlouisquinn.com/pogolumina_PcalifornicusInfo.htm"><span class="glossLinkSm"><em>Pogonomyrmex californicus</em></span></a> worker heads back to the nest.
</div>](https://photos.smugmug.com/NorthAmericanPogosbyBehavior/Plants/i-9SgRjk4/0/dee023d2/Ti/4398_10_7Dc-Ti.jpg)
![<span class="captionImageInfo"> ● Wanapum Rec. Area [Kittitas Co], WA USA [el. 190 m / 623 ft]</span> <a href="http://maps.google.com/maps/ms?ie=UTF8&hl=en&t=h&msa=0&msid=100103460138962878270.000470bd413e9e793ba1d&ll=46.905483,-119.9903&spn=0.164191,0.291824&z=11&source=embed"><span class="mapLink">view location in Google Maps »</span></a>
<span class="captionImageInfo"> ● 6/4/09 8:00AM sunny, air temp: 23°C / 74°F</span>
<div class="captionImageMain">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 <a href="http://www.davidlouisquinn.com/pogolumina_PsalinusInfo.htm"><span class="glossLinkSm"><em>Pogonomyrmex salinus</em></span></a> worker appeared to be going over the petals with her mouthparts - possibly <a href="http://www.davidlouisquinn.com/pogolumina_feedingInfo.htm"><span class="glossLinkSm">collecting nectar</span></a>, or moisture. At one point, the ant attempted to cut through the stem, just below the flower - but to no avail.</div>](https://photos.smugmug.com/NorthAmericanPogosbyBehavior/Plants/i-mjnjwCc/6/7845a1a5/Ti/2485_09_Rc-Ti.jpg)
![<span class="captionImageInfo"> ● SW of Pyramid Lake [Washoe Co], NV USA [el. 1323 m / 4341 ft]</span> <a href="http://maps.google.com/maps/ms?hl=en&ie=UTF8&t=h&msa=0&msid=100103460138962878270.00048ab74785d385f672e&ll=39.800096,-119.665833&spn=0.738551,1.167297&z=9&source=embed"><span class="mapLink">view location in Google Maps »</span></a>
<span class="captionImageInfo"> ● 6/24/10 7:18AM mostly sunny, air temp: 16°C / 61°F</span>
<div class="captionImageMain">[IMAGE 1 of 4] About two dozen <a href="http://www.davidlouisquinn.com/pogolumina_PoccidentalisInfo.htm"><span class="glossLinkSm"><em>P.occidentalis</em></span></a> workers started <a href="http://www.davidlouisquinn.com/pogolumina_feedingInfo.htm"><span class="glossLinkSm">foraging</span></a> along an approximately 4.5m / 15 ft long trunk trail <span class="footnoteTag">[1]</span>, that extended from the nest in a northwesterly direction. Some of them began finding petals from saltbush plants (<em>Atriplex sp.</em>), and carrying them back to the nest from as far away as 3m / 10 feet. <span class ="footnoteTag">[scroll down for additional notes/references]</span>
</div>
<div class="captionRefFootnote">ADDITIONAL NOTES/REFERENCES:
<em> <a href="http://www.davidlouisquinn.com/pogolumina_PoccidentalisInfo.htm"><span class="glossLinkSm">Pogonomyrmex occidentalis</span></a>, and <a href="http://www.davidlouisquinn.com/pogolumina_PsalinusInfo.htm"><span class="glossLinkSm">P.salinus</span></a> 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 <a href="http://www.davidlouisquinn.com/pogolumina_feedingInfo.htm"><span class="glossLinkSm"> seeds or other food items</span></a>. 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 <a href="http://www.davidlouisquinn.com/pogolumina_PogonomyrmexInfo.htm"><span class="glossLinkSm">Pogonomyrmex</span></a> 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 <a href="http://www.davidlouisquinn.com/pogolumina_PbarbatusInfo.htm"><span class="glossLinkSm">(P. barbatus)</span></a>, 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
</em>
</div>](https://photos.smugmug.com/NorthAmericanPogosbyBehavior/Plants/i-DhqXX2b/0/d2f1bd50/Ti/4564_10_7Dc-Ti.jpg)
![<span class="captionImageInfo"> ● SW of Pyramid Lake [Washoe Co], NV USA [el. 1323 m / 4341 ft]</span> <a href="http://maps.google.com/maps/ms?hl=en&ie=UTF8&t=h&msa=0&msid=100103460138962878270.00048ab74785d385f672e&ll=39.800096,-119.665833&spn=0.738551,1.167297&z=9&source=embed"><span class="mapLink">view location in Google Maps »</span></a>
<span class="captionImageInfo"> ● 6/24/10 7:36AM mostly sunny, air temp: 18°C / 64°F</span>
<div class="captionImageMain">[IMAGE 2 of 4] About two dozen <a href="http://www.davidlouisquinn.com/pogolumina_PoccidentalisInfo.htm"><span class="glossLinkSm"><em>P.occidentalis</em></span></a> workers started <a href="http://www.davidlouisquinn.com/pogolumina_feedingInfo.htm"><span class="glossLinkSm">foraging</span></a> along an approximately 4.5m / 15 ft long trunk trail <span class="footnoteTag">[1]</span>, that extended from the nest in a northwesterly direction. Some of them began finding petals from saltbush plants (<em>Atriplex sp.</em>), and carrying them back to the nest from as far away as 3m / 10 feet. <span class ="footnoteTag">[scroll down for additional notes/references]</span>
</div>
<div class="captionRefFootnote">ADDITIONAL NOTES/REFERENCES:
<em> <a href="http://www.davidlouisquinn.com/pogolumina_PoccidentalisInfo.htm"><span class="glossLinkSm">Pogonomyrmex occidentalis</span></a>, and <a href="http://www.davidlouisquinn.com/pogolumina_PsalinusInfo.htm"><span class="glossLinkSm">P.salinus</span></a> 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 <a href="http://www.davidlouisquinn.com/pogolumina_feedingInfo.htm"><span class="glossLinkSm"> seeds or other food items</span></a>. 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 <a href="http://www.davidlouisquinn.com/pogolumina_PogonomyrmexInfo.htm"><span class="glossLinkSm">Pogonomyrmex</span></a> 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 <a href="http://www.davidlouisquinn.com/pogolumina_PbarbatusInfo.htm"><span class="glossLinkSm">(P. barbatus)</span></a>, 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
</em>
</div>](https://photos.smugmug.com/NorthAmericanPogosbyBehavior/Plants/i-cMrv3rr/0/9b2cb334/Ti/4612_10_7Dc-Ti.jpg)
![<span class="captionImageInfo"> ● SW of Pyramid Lake [Washoe Co], NV USA [el. 1323 m / 4341 ft]</span> <a href="http://maps.google.com/maps/ms?hl=en&ie=UTF8&t=h&msa=0&msid=100103460138962878270.00048ab74785d385f672e&ll=39.800096,-119.665833&spn=0.738551,1.167297&z=9&source=embed"><span class="mapLink">view location in Google Maps »</span></a>
<span class="captionImageInfo"> ● 6/24/10 7:47AM mostly sunny, air temp: 20°C / 69°F</span>
<div class="captionImageMain">[IMAGE 3 of 4] About two dozen <a href="http://www.davidlouisquinn.com/pogolumina_PoccidentalisInfo.htm"><span class="glossLinkSm"><em>P.occidentalis</em></span></a> workers started <a href="http://www.davidlouisquinn.com/pogolumina_feedingInfo.htm"><span class="glossLinkSm">foraging</span></a> along an approximately 4.5m / 15 ft long trunk trail <span class="footnoteTag">[1]</span>, that extended from the nest in a northwesterly direction. Some of them began finding petals from saltbush plants (<em>Atriplex sp.</em>), and carrying them back to the nest from as far away as 3m / 10 feet. <span class ="footnoteTag">[scroll down for additional notes/references]</span>
</div>
<div class="captionRefFootnote">ADDITIONAL NOTES/REFERENCES:
<em> <a href="http://www.davidlouisquinn.com/pogolumina_PoccidentalisInfo.htm"><span class="glossLinkSm">Pogonomyrmex occidentalis</span></a>, and <a href="http://www.davidlouisquinn.com/pogolumina_PsalinusInfo.htm"><span class="glossLinkSm">P.salinus</span></a> 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 <a href="http://www.davidlouisquinn.com/pogolumina_feedingInfo.htm"><span class="glossLinkSm"> seeds or other food items</span></a>. 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 <a href="http://www.davidlouisquinn.com/pogolumina_PogonomyrmexInfo.htm"><span class="glossLinkSm">Pogonomyrmex</span></a> 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 <a href="http://www.davidlouisquinn.com/pogolumina_PbarbatusInfo.htm"><span class="glossLinkSm">(P. barbatus)</span></a>, 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
</em>
</div>](https://photos.smugmug.com/NorthAmericanPogosbyBehavior/Plants/i-LHfCzS5/1/9b232780/Ti/4637_10_7Dc-Ti.jpg)
![<span class="captionImageInfo"> ● SW of Pyramid Lake [Washoe Co], NV USA [el. 1323 m / 4341 ft]</span> <a href="http://maps.google.com/maps/ms?hl=en&ie=UTF8&t=h&msa=0&msid=100103460138962878270.00048ab74785d385f672e&ll=39.800096,-119.665833&spn=0.738551,1.167297&z=9&source=embed"><span class="mapLink">view location in Google Maps »</span></a>
<span class="captionImageInfo"> ● 6/24/10 8:01AM mostly sunny, air temp: 20°C / 69°F</span>
<div class="captionImageMain">[IMAGE 4 of 4] About two dozen <a href="http://www.davidlouisquinn.com/pogolumina_PoccidentalisInfo.htm"><span class="glossLinkSm"><em>P.occidentalis</em></span></a> workers started <a href="http://www.davidlouisquinn.com/pogolumina_feedingInfo.htm"><span class="glossLinkSm">foraging</span></a> along an approximately 4.5m / 15 ft long trunk trail <span class="footnoteTag">[1]</span>, that extended from the nest in a northwesterly direction. Some of them began finding petals from saltbush plants (<em>Atriplex sp.</em>), and carrying them back to the nest from as far away as 3m / 10 feet. The <a href="http://www.davidlouisquinn.com/pogolumina_psammophoreInfo.htm"><span class="glossLinkSm">psammophore</span></a> of this worker can be clearly seen. <span class ="footnoteTag">[scroll down for additional notes/references]</span>
</div>
<div class="captionRefFootnote">ADDITIONAL NOTES/REFERENCES:
<em> <a href="http://www.davidlouisquinn.com/pogolumina_PoccidentalisInfo.htm"><span class="glossLinkSm">Pogonomyrmex occidentalis</span></a>, and <a href="http://www.davidlouisquinn.com/pogolumina_PsalinusInfo.htm"><span class="glossLinkSm">P.salinus</span></a> 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 <a href="http://www.davidlouisquinn.com/pogolumina_feedingInfo.htm"><span class="glossLinkSm"> seeds or other food items</span></a>. 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 <a href="http://www.davidlouisquinn.com/pogolumina_PogonomyrmexInfo.htm"><span class="glossLinkSm">Pogonomyrmex</span></a> 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 <a href="http://www.davidlouisquinn.com/pogolumina_PbarbatusInfo.htm"><span class="glossLinkSm">(P. barbatus)</span></a>, 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
</em>
</div>](https://photos.smugmug.com/NorthAmericanPogosbyBehavior/Plants/i-JqTCjcx/0/4bb99ec0/Ti/4645_10_7Dc-Ti.jpg)
![<span class="captionImageInfo"> ● Wanapum Rec. Area [Kittitas Co], WA USA [el. 190 m / 623 ft]</span> <a href="http://maps.google.com/maps/ms?ie=UTF8&hl=en&t=h&msa=0&msid=100103460138962878270.000470bd413e9e793ba1d&ll=46.905483,-119.9903&spn=0.164191,0.291824&z=11&source=embed"><span class="mapLink">view location in Google Maps »</span></a>
<span class="captionImageInfo"> ● 5/10/09 12:36PM sunny, air temp: 23°C / 74°F</span>
<div class="captionImageMain">[IMAGE 1 of 2] An attempt by <span class="glossLinkSm"><em>P. salinus</em></span></a> workers to <a href="http://www.davidlouisquinn.com/pogolumina_nestClearingInfo.htm"><span class="glossLinkSm">remove</span></a> a balsamroot plant (<em>Balsamhoriza sp.</em>) from the vicinity of their nest. <span class ="footnoteTag">[scroll down for additional notes/references]</span></div>
<div class="captionRefFootnote">ADDITIONAL NOTES/REFERENCES:
<em>On this Spring day, we came upon approx. twenty <em>P.salinus</em> workers apparently attempting to cut down a relatively large balsamroot plant (<em>Balsamorhiza sp.</em>) less than .3 m /1 ft from a nest with two entrances. <a href="http://www.davidlouisquinn.com/pogolumina_balsamroot_cuttingInfo.htm"><span class="glossLinkSm">[see additional images » ]</span></a> Working slowly, they used their <a href="http://www.davidlouisquinn.com/pogolumina_mandiblesInfo.htm"><span class="glossLinkSm">mandibles</span></a> to slice out substantial portions of the leaves, which fell to the ground. We did not observe any workers retrieving the cut-out pieces, but the questions did occur: could this also be a foraging technique (with the cut-out pieces to be retrieved later?) or could the ants also be consuming liquids from the plant as they cut through these green leaves?
Returning to this site exactly 2 months later, we observed the plant still intact (though dry), with only the one leaf (that the ants are pictured on here) substantially chewed away. Considering the size of the plant, the thickness of the leaves, and the slow rate at which they were making progress, it's not surprising that they failed to remove it, if that was indeed the intention.
A plant with leaves of considerable surface area and thickness (like this balsamroot) would seem to be very challenging for these ants to cut down. Cole states: "I carefully observed <a href="http://www.davidlouisquinn.com/pogolumina_PoccidentalisInfo.htm"><span class="glossLinkSm">occidentalis</span></a> workers cutting down a large plant of wild lettuce at the base of a mound. Fourteen days of cutting were required for the plant, 12.1 centimeters high, to be reduced to a mere stump of 0.2 centimeters, only a few ants working at a time."
·Cole, A.C. 1932. The Relation of the Ant, Pogonomyrmex occidentalis CR., to its Habitat. Ohio Journal of Science, 32:133-46, Ohio State University</em>
</div>](https://photos.smugmug.com/NorthAmericanPogosbyBehavior/Plants/i-57X5RHn/10/f46f9f04/Ti/2071_09_Rf-Ti.jpg)
![<span class="captionImageInfo"> ● Wanapum Rec. Area [Kittitas Co], WA USA [el. 190 m / 623 ft]</span> <a href="http://maps.google.com/maps/ms?ie=UTF8&hl=en&t=h&msa=0&msid=100103460138962878270.000470bd413e9e793ba1d&ll=46.905483,-119.9903&spn=0.164191,0.291824&z=11&source=embed"><span class="mapLink">view location in Google Maps »</span></a>
<span class="captionImageInfo"> ● 5/10/09 12:23PM sunny, air temp: 23°C / 74°F</span>
<div class="captionImageMain">[IMAGE 2 of 2] An attempt by <span class="glossLinkSm"><em>P. salinus</em></span></a> workers to <a href="http://www.davidlouisquinn.com/pogolumina_nestClearingInfo.htm"><span class="glossLinkSm">remove</span></a> a balsamroot plant (<em>Balsamhoriza sp.</em>) from the vicinity of their nest. <span class ="footnoteTag">[scroll down for additional notes/references - also see previous image]</span></div>
<div class="captionRefFootnote">ADDITIONAL NOTES/REFERENCES:
<em>On this Spring day, we came upon approx. twenty <em>P.salinus</em> workers apparently attempting to cut down a relatively large balsamroot plant (<em>Balsamorhiza sp.</em>) less than .3 m /1 ft from a nest with two entrances. <a href="http://www.davidlouisquinn.com/pogolumina_balsamroot_cuttingInfo.htm"><span class="glossLinkSm">[see additional images » ]</span></a> Working slowly, they used their <a href="http://www.davidlouisquinn.com/pogolumina_mandiblesInfo.htm"><span class="glossLinkSm">mandibles</span></a> to slice out substantial portions of the leaves, which fell to the ground. We did not observe any workers retrieving the cut-out pieces, but the questions did occur: could this also be a foraging technique (with the cut-out pieces to be retrieved later?) or could the ants also be consuming liquids from the plant as they cut through these green leaves?
Returning to this site exactly 2 months later, we observed the plant still intact (though dry), with only the one leaf (that the ants are pictured on here) substantially chewed away. Considering the size of the plant, the thickness of the leaves, and the slow rate at which they were making progress, it's not surprising that they failed to remove it, if that was indeed the intention.
A plant with leaves of considerable surface area and thickness (like this balsamroot) would seem to be very challenging for these ants to cut down. Cole states: "I carefully observed <a href="http://www.davidlouisquinn.com/pogolumina_PoccidentalisInfo.htm"><span class="glossLinkSm">occidentalis</span></a> workers cutting down a large plant of wild lettuce at the base of a mound. Fourteen days of cutting were required for the plant, 12.1 centimeters high, to be reduced to a mere stump of 0.2 centimeters, only a few ants working at a time."
·Cole, A.C. 1932. The Relation of the Ant, Pogonomyrmex occidentalis CR., to its Habitat. Ohio Journal of Science, 32:133-46, Ohio State University</em>
</div>](https://photos.smugmug.com/NorthAmericanPogosbyBehavior/Plants/i-rKLVJkB/8/34190171/Ti/2052_09_Rf-Ti.jpg)
![<span class="captionImageInfo"> ● Pyramid Lake Indian Res. (Paiute), NV USA [el. 1202 m / 3945 ft]</span> <a href="http://maps.google.com/maps/ms?hl=en&ie=UTF8&t=h&msa=0&msid=100103460138962878270.00048ab88a421ad2e2b90&ll=39.930801,-119.388428&spn=0.737146,1.167297&z=9&source=embed"><span class="mapLink">view location in Google Maps »</span></a><span class="captionImageInfo">
● 6/22/10 9:38AM sunny, air temp: 22°C / 72°F</span>
<div class="captionImageMain">[IMAGE 1 of 3] The ability of <a href="http://www.davidlouisquinn.com/pogolumina_PogonomyrmexInfo.htm"><span class="glossLinkSm"><em>Pogonomymrex</em></span></a> ants to carry excavated sand in their <a href="http://www.davidlouisquinn.com/pogolumina_psammophoreInfo.htm"><span class="glossLinkSm">psammophores</span></a> is well known and documented. But, despite a few vague references on the Web <span class="footnoteTag">[1]</span>, we have not yet found any descriptions of these ants using this structure to gather and/or transport seeds in the wild, under natural conditions <span class="footnoteTag">[2]</span> (nor have we observed this behavior ourselves, prior to 6/22/10).<br>
These <a href="http://www.davidlouisquinn.com/pogolumina_PcalifornicusInfo.htm"><span class="glossLinkSm"><em>Pogonomyrmex californicus</em></span></a> workers were picking up (and transporting) multiple <a href="http://www.davidlouisquinn.com/pogolumina_dsophia_seedInfo.htm"><span class="glossLinkSm">seeds of <em>Descurainia sophia </em></span></a> (a.k.a. flixweed). The nest of these ants was located in a sandy area, under a living <em>Salsola</em> (tumbleweed) plant - surrounded by many other plants including (and most abundantly) <em>Descurainia sophia</em>.<br>
The multiple-seed-gathering behavior was taking place approx. 60 cm / 2 feet away from the nest entrance - in an area strewn with the tiny orange <em>D. sophia</em> seeds. It was probably the high density of seeds (estimated to be 0.3 - 0.5 per cm²), along with their small size and proximity to the nest, that made this unusual type of foraging possible <span class="footnoteTag">[2]</span>. Workers returning from other areas, and from greater distances, carried only single items (as is usual for these ants). Individual workers were observed to successfully carry three of these seeds at a time, usually with one in the psammophore, and two 'stacked' in the <a href="http://www.davidlouisquinn.com/pogolumina_mandiblesInfo.htm"><span class="glossLinkSm">mandibles</span></a> (one worker was seen to have two seeds, side by side, in the psammophore). As can be seen in these images, the Pogos sometimes used the tips of their antennae to maneuver the seeds into position, before attempting to pick them up. Once fully loaded, they headed straight for the nest. There were many empty seedpods in the area where the seeds were being gathered, and it is possible that the ants had broken open the pods earlier and liberated the seeds - but it is just as likely that the seeds fell naturally. One worker was seen manipulating a seedpod, but it was already empty. <span class ="footnoteTag">[scroll down for additional notes/references]</span>
</div>
<div class="captionRefFootnote">ADDITIONAL NOTES/REFERENCES:
<em>
[1] Most notably, the Wikipedia article on Pogonomyrmex states "The psammophore are (sic) used for gathering small seeds, helping to increase the efficiency of transportation of fine sand and pebbles during nest construction, or to carry eggs."
[2] Pogonomyrmex ants have been known to transport multiple food items (using the psammophore and mandibles) when presented with bait piles consisting of cracked wheat, during controlled experiments. These bait piles offered the ants very small particles, at higher densities than would be found under natural conditions. During these experiments, <a href="http://www.davidlouisquinn.com/pogolumina_PoccidentalisInfo.htm"><span class="glossLinkSm"><em>P.occidentalis</em></span></a> workers did not start using their psammophores until seed densities exceeded 0.5 cm² As far as the use of psammophores by foragers under natural conditions, Porter & Jorgensen state, "Apparently, this behavior does not occur or it is very uncommon."
·Porter, S.D., and C.D. Jorgensen. 1990. Psammophores: Do Harvester Ants (Hymenoptera: Formicidae) Use These Pouches to Transport Seeds? Journal of the Kansas Entomological Society. 63(1) 138 -149
</div>](https://photos.smugmug.com/NorthAmericanPogosbyBehavior/Plants/i-RZ7XSTh/0/5f0d9932/Ti/4347_10_7Dc-Ti.jpg)
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