● 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
![● Duval Mine Rd, Sahuarita [Pima Co], AZ USA [el. 882 m / 2893 ft] view location in Google Maps »
● 11/06/10 10:01AM sunny, air temp: 24°C / 76°F
[IMAGE 1 of 5] Whenever we approached either of the two P. bicolor nests at this location, one or two workers would immediately climb a grass stem and remain there, while appearing to watch us closely. Occasionally, the mandibles would be opened in a feeble defensive display. The rest of the workers (on the ground) went about their business, and ignored us completely. As mentioned earlier, the ants made no attempt to bite or sting, no matter how closely we approached. The very fine and silky-looking surface sculpture can also be seen in these images.](https://photos.smugmug.com/PreviewPortfolio/i-H5KdsKP/0/c2a0726d/S/6858_10_7Df-S.jpg)
![● Catalina State Park, Tucson [Pima Co], AZ USA [el. 800 m / 2625 ft] view location in Google Maps »
● 11/02/10 9:39AM sunny, air temp: 24°C / 76°F
The sharp, and powerful mandibles of this Acromyrmex versicolor worker can be seen clearly in this image. These cutting and grasping tools allow the ants to efficiently remove large amounts of vegetation from a wide variety of plants. The freshly cut plant material is then brought back to the nest where it serves as a medium for the growth of a nutritious, symbiotic fungus.](https://photos.smugmug.com/PreviewPortfolio/i-27vNsCV/1/1683a72e/S/6251_10_7D-S.jpg)
![● 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 background, this P. salinus worker searches a plant for nectar in central Washington state.](https://photos.smugmug.com/PreviewPortfolio/i-TJ7WxTt/0/4af5b57d/S/3360_10_7Df-S.jpg)
![● 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](https://photos.smugmug.com/PreviewPortfolio/i-QJR5DHV/8/9f4c4470/S/2088_09_Rf-S.jpg)
![● Fernley [Lyon Co], NV USA [el. 1271 m / 4171 ft] view location in Google Maps »
● 6/23/10 6:27AM partly cloudy, air temp: 17°C / 62°F
[IMAGE 2 of 2] A beautiful Pogonomyrmex californicus worker pauses briefly after emerging from her nest (cropped view).](https://photos.smugmug.com/PreviewPortfolio/i-PxQvJcZ/1/98621fa1/S/4406_10_7Dc-S.jpg)
![● 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](https://photos.smugmug.com/PreviewPortfolio/i-DTBFXKV/0/8887f450/S/3005_10_7Dc-S.jpg)