Home, home building, and home improvement. Pogonomyrmex
ants and their nests
, at various locations in North America.
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![pogolumina > ● NW of Mattawa [Grant Co], WA USA [el. 152 m / 500 ft] view location in Google Maps »
● 9/4/08 7:52AM sunny, air temp: 21°C / 69°F
This P. salinus nest is in the process of transitioning from a crater, to a dome. The wide crater opening can still be seen on the left (filled with workers), while the right side of the nest is expanding and rising into a dome-like structure. Much of the mound surface is covered with chaff, and chewed-down stalks of grass can be seen as well. An immature black widow spider's (Latrodectus hesperus) web is suspended above the left side of the nest - apparently the ants were not diligent enough in their plant removal operations...[scroll down for additional notes/references]
ADDITIONAL NOTES/REFERENCES:
Based on our observations, juvenile western black widow spiders (Latrodectus hesperus) are frequent predators of P.salinus ants in central Washington state. We have not observed any adult L. hesperus preying on Pogonomyrmex salinus, nor have we seen any near the ants, or their nests. This is consistent with the findings of MacKay, in his study of L. hesperus and Pogonomyrmex rugosus, where it was observed that females apparently stop feeding on ants when they become adults (according to MacKay, it is possible that males continue to prey on the ants throughout their lives, though as noted above, we have not yet observed this).
Latrodectus hesperus spiders often position themselves in a web just outside the entrance to a Pogo nest. Pogos have been known to close a nest entrance, and open a new one a short distance away, to avoid these predators. Some species, like Pogonomyrmex rugosus, may stop foraging altogether (living on stored seeds), until a spider (or spiders) leave the vicinity of the nest (L. hesperus will move to an active nest nearby, if this occurs). We have seen evidence of these behaviors in Pogonomyrmex salinus (in central WA) as well, with web-covered entrances apparently blocked with debris by the ants, and no foraging activity occurring. Despite their powerful mandibles and formidable stings, Pogos do not appear to be able (or willing) to attack, kill, or repel these predators directly - relying instead on the more passive methods of avoidance mentioned above. We have also observed P. salinus workers attempting to remove webs (most likely webs of L. hesperus) from the vicinity of the nest entrance, however in these cases, no spiders were present.
In areas where we observe western black widows preying on P. salinus, it is usually evident that the spiders are not specializing on ants to the exclusion of all other arthropods, as we sopmetimes see the remains of beetles, and other insects in their webs.
·MacKay, W. 1982. The Effect of Predation of Western Widow Spiders (Aranea; Theridiidae) on Harvester Ants (Hymenoptera: Formicidae). Oecologia (Berl) (1982) 53:406-411](http://www.pogolumina.net/NorthAmericanPogosbyBehavior/Nests/i-c9TmZHD/0/Ti/0894_08_Rc-Ti.jpg "pogolumina > ● NW of Mattawa [Grant Co], WA USA [el. 152 m / 500 ft] view location in Google Maps »
● 9/4/08 7:52AM sunny, air temp: 21°C / 69°F
This P. salinus nest is in the process of transitioning from a crater, to a dome. The wide crater opening can still be seen on the left (filled with workers), while the right side of the nest is expanding and rising into a dome-like structure. Much of the mound surface is covered with chaff, and chewed-down stalks of grass can be seen as well. An immature black widow spider's (Latrodectus hesperus) web is suspended above the left side of the nest - apparently the ants were not diligent enough in their plant removal operations...[scroll down for additional notes/references]
ADDITIONAL NOTES/REFERENCES:
Based on our observations, juvenile western black widow spiders (Latrodectus hesperus) are frequent predators of P.salinus ants in central Washington state. We have not observed any adult L. hesperus preying on Pogonomyrmex salinus, nor have we seen any near the ants, or their nests. This is consistent with the findings of MacKay, in his study of L. hesperus and Pogonomyrmex rugosus, where it was observed that females apparently stop feeding on ants when they become adults (according to MacKay, it is possible that males continue to prey on the ants throughout their lives, though as noted above, we have not yet observed this).
Latrodectus hesperus spiders often position themselves in a web just outside the entrance to a Pogo nest. Pogos have been known to close a nest entrance, and open a new one a short distance away, to avoid these predators. Some species, like Pogonomyrmex rugosus, may stop foraging altogether (living on stored seeds), until a spider (or spiders) leave the vicinity of the nest (L. hesperus will move to an active nest nearby, if this occurs). We have seen evidence of these behaviors in Pogonomyrmex salinus (in central WA) as well, with web-covered entrances apparently blocked with debris by the ants, and no foraging activity occurring. Despite their powerful mandibles and formidable stings, Pogos do not appear to be able (or willing) to attack, kill, or repel these predators directly - relying instead on the more passive methods of avoidance mentioned above. We have also observed P. salinus workers attempting to remove webs (most likely webs of L. hesperus) from the vicinity of the nest entrance, however in these cases, no spiders were present.
In areas where we observe western black widows preying on P. salinus, it is usually evident that the spiders are not specializing on ants to the exclusion of all other arthropods, as we sopmetimes see the remains of beetles, and other insects in their webs.
·MacKay, W. 1982. The Effect of Predation of Western Widow Spiders (Aranea; Theridiidae) on Harvester Ants (Hymenoptera: Formicidae). Oecologia (Berl) (1982) 53:406-411")
![pogolumina > ● Horse Ridge, SE of Bend [Deschutes Co], OR USA [el. 1310 m / 4297 ft] view location in Google Maps »
● 7/20/09 6:50AM sunny, air temp: 10°C / 50°F
This massive P. salinus nest is built around large rocks, and covered with a staggering amount of gravel. The nest entrance (there was only one, last time we visited) is located under the edge of the large central boulder. The distance between the two yellow markers is approximately 1.9 m / 76 inches. [scroll down for additional notes/references]
ADDITIONAL NOTES/REFERENCES:
On our first visit to this nest (7/15/08) the air temperature was 28°C / 82°F, and the ants were foraging along a trail in the shade of a large rock. Soon after I approached the entrance, many dozens of workers (defenders) poured out, and ran toward me. Most turned back after I backed away, but approximately 10 workers continued pursuing me more than 3.6 m / 12 ft from the entrance, often stopping to stand on small pebbles and twigs while waving their antennae wildly, and opening their mandibles.
At many other P. salinus nests nearby, workers were not aggressive, and ignored us - even when inches away from the entrances.
We think the physical size of the large nest (mentioned above), may have something to do with the very aggressive worker response to our presence. The gravel-covering of this nest was approx. 1.9 m / 76 in. wide, measured on its longest axis. This means that I had to walk over a large portion of the nest 'dome' in order to reach the entrance - undoubtedly collapsing many tunnels and galleries that lay just below the gravel covered surface. This would result in alarm pheromones being released in great quantities by the ants underfoot, alerting nestmates to the defense of their colony.](http://www.pogolumina.net/NorthAmericanPogosbyBehavior/Nests/i-pzFbT5R/0/Ti/0464_09_40D-Ti.jpg "pogolumina > ● Horse Ridge, SE of Bend [Deschutes Co], OR USA [el. 1310 m / 4297 ft] view location in Google Maps »
● 7/20/09 6:50AM sunny, air temp: 10°C / 50°F
This massive P. salinus nest is built around large rocks, and covered with a staggering amount of gravel. The nest entrance (there was only one, last time we visited) is located under the edge of the large central boulder. The distance between the two yellow markers is approximately 1.9 m / 76 inches. [scroll down for additional notes/references]
ADDITIONAL NOTES/REFERENCES:
On our first visit to this nest (7/15/08) the air temperature was 28°C / 82°F, and the ants were foraging along a trail in the shade of a large rock. Soon after I approached the entrance, many dozens of workers (defenders) poured out, and ran toward me. Most turned back after I backed away, but approximately 10 workers continued pursuing me more than 3.6 m / 12 ft from the entrance, often stopping to stand on small pebbles and twigs while waving their antennae wildly, and opening their mandibles.
At many other P. salinus nests nearby, workers were not aggressive, and ignored us - even when inches away from the entrances.
We think the physical size of the large nest (mentioned above), may have something to do with the very aggressive worker response to our presence. The gravel-covering of this nest was approx. 1.9 m / 76 in. wide, measured on its longest axis. This means that I had to walk over a large portion of the nest 'dome' in order to reach the entrance - undoubtedly collapsing many tunnels and galleries that lay just below the gravel covered surface. This would result in alarm pheromones being released in great quantities by the ants underfoot, alerting nestmates to the defense of their colony.")
![pogolumina > ● HWY 17, Sun Lakes S.P. [Grant Co], WA USA [el. 340 m / 1116 ft] view location in Google Maps »
● 9/21/08 11:58AM overcast, air temp: NA
The gravel covering of this unique P. salinus nest, extended approximately 1 m / 39 inches on its longest axis. The mound takes the form of a low dome built around a large central rock. Mineral deposits abundant in this area of central Washington state are responsible for the sprinkling of white particles amongst the gravel, and for the white rock face.](http://www.pogolumina.net/NorthAmericanPogosbyBehavior/Nests/i-Brr8zhh/0/Ti/1499_08_Rf-Ti.jpg "pogolumina > ● HWY 17, Sun Lakes S.P. [Grant Co], WA USA [el. 340 m / 1116 ft] view location in Google Maps »
● 9/21/08 11:58AM overcast, air temp: NA
The gravel covering of this unique P. salinus nest, extended approximately 1 m / 39 inches on its longest axis. The mound takes the form of a low dome built around a large central rock. Mineral deposits abundant in this area of central Washington state are responsible for the sprinkling of white particles amongst the gravel, and for the white rock face.")
![pogolumina > ● NW of Mattawa [Grant Co], WA USA [el. 152 m / 500 ft] view location in Google Maps »
● 9/21/08 9:28AM overcast, air temp: NA
Here we see a gravel covered crater nest of P. salinus, surrounded by cut-down grass stems, and a large amount of chaff.](http://www.pogolumina.net/NorthAmericanPogosbyBehavior/Nests/i-GPfZ4Hb/0/Ti/1407_08_Rf-Ti.jpg "pogolumina > ● NW of Mattawa [Grant Co], WA USA [el. 152 m / 500 ft] view location in Google Maps »
● 9/21/08 9:28AM overcast, air temp: NA
Here we see a gravel covered crater nest of P. salinus, surrounded by cut-down grass stems, and a large amount of chaff.")
![pogolumina > ● Mission Espada, San Antonio [Bexar Co], TX USA
● 3/01/10 3:14PM sun/clouds, air temp: 15°C / 60°F
[IMAGE 1 of 4] Late winter/early spring nest maintenance. These Pogonomyrmex barbatus workers were slowly bringing loads of sand/soil up from the depths of their nest. They appeared to be utilizing their psammophores in some cases, and their mandibles alone, in others - depending on the moisture content of the soil they were transporting. It had rained the day before these images were captured, and much of the soil was quite moist and clumped - allowing it to be easily picked up and carried in the mandibles of these workers (like a clump of sticky rice can be picked up with chopsticks).](http://www.pogolumina.net/NorthAmericanPogosbyBehavior/Nests/i-N697dTR/0/Ti/IMG_0549_10_7Dc-Ti.jpg "pogolumina > ● Mission Espada, San Antonio [Bexar Co], TX USA
● 3/01/10 3:14PM sun/clouds, air temp: 15°C / 60°F
[IMAGE 1 of 4] Late winter/early spring nest maintenance. These Pogonomyrmex barbatus workers were slowly bringing loads of sand/soil up from the depths of their nest. They appeared to be utilizing their psammophores in some cases, and their mandibles alone, in others - depending on the moisture content of the soil they were transporting. It had rained the day before these images were captured, and much of the soil was quite moist and clumped - allowing it to be easily picked up and carried in the mandibles of these workers (like a clump of sticky rice can be picked up with chopsticks).")
![pogolumina > ● Mission Espada, San Antonio [Bexar Co], TX USA
● 3/01/10 3:15PM sun/clouds, air temp: 15°C / 60°F
[IMAGE 2 of 4] Late winter/early spring nest maintenance. These Pogonomyrmex barbatus workers were slowly bringing loads of sand/soil up from the depths of their nest. They appeared to be utilizing their psammophores in some cases, and their mandibles alone, in others - depending on the moisture content of the soil they were transporting. It had rained the day before these images were captured, and much of the soil was quite moist and clumped - allowing it to be easily picked up and carried in the mandibles of these workers (like a clump of sticky rice can be picked up with chopsticks).](http://www.pogolumina.net/NorthAmericanPogosbyBehavior/Nests/i-cqHsCVQ/0/Ti/IMG_0550_10_7Dc-Ti.jpg "pogolumina > ● Mission Espada, San Antonio [Bexar Co], TX USA
● 3/01/10 3:15PM sun/clouds, air temp: 15°C / 60°F
[IMAGE 2 of 4] Late winter/early spring nest maintenance. These Pogonomyrmex barbatus workers were slowly bringing loads of sand/soil up from the depths of their nest. They appeared to be utilizing their psammophores in some cases, and their mandibles alone, in others - depending on the moisture content of the soil they were transporting. It had rained the day before these images were captured, and much of the soil was quite moist and clumped - allowing it to be easily picked up and carried in the mandibles of these workers (like a clump of sticky rice can be picked up with chopsticks).")
![pogolumina > ● Mission Espada, San Antonio [Bexar Co], TX USA
● 3/01/10 3:21PM sun/clouds, air temp: 15°C / 60°F
[IMAGE 3 of 4] Late winter/early spring nest maintenance. These Pogonomyrmex barbatus workers were slowly bringing loads of sand/soil up from the depths of their nest. They appeared to be utilizing their psammophores in some cases, and their mandibles alone, in others - depending on the moisture content of the soil they were transporting. It had rained the day before these images were captured, and much of the soil was quite moist and clumped - allowing it to be easily picked up and carried in the mandibles of these workers (like a clump of sticky rice can be picked up with chopsticks). NOTE: This worker has just dropped her load of sand.](http://www.pogolumina.net/NorthAmericanPogosbyBehavior/Nests/i-dLmj55d/0/Ti/IMG_0576_10_7Dc-Ti.jpg "pogolumina > ● Mission Espada, San Antonio [Bexar Co], TX USA
● 3/01/10 3:21PM sun/clouds, air temp: 15°C / 60°F
[IMAGE 3 of 4] Late winter/early spring nest maintenance. These Pogonomyrmex barbatus workers were slowly bringing loads of sand/soil up from the depths of their nest. They appeared to be utilizing their psammophores in some cases, and their mandibles alone, in others - depending on the moisture content of the soil they were transporting. It had rained the day before these images were captured, and much of the soil was quite moist and clumped - allowing it to be easily picked up and carried in the mandibles of these workers (like a clump of sticky rice can be picked up with chopsticks). NOTE: This worker has just dropped her load of sand.")
![pogolumina > ● Mission Espada, San Antonio Missions N.H.P., TX USA
● 3/01/10 3:25PM sun/clouds, air temp: 15°C / 60°F
[IMAGE 4 of 4] Late winter/early spring nest maintenance. These Pogonomyrmex barbatus workers were slowly bringing loads of sand/soil up from the depths of their nest. They appeared to be utilizing their psammophores in some cases, and their mandibles alone, in others - depending on the moisture content of the soil they were transporting. It had rained the day before these images were captured, and much of the soil was quite moist and clumped - allowing it to be easily picked up and carried in the mandibles of these workers (like a clump of sticky rice can be picked up with chopsticks).](http://www.pogolumina.net/NorthAmericanPogosbyBehavior/Nests/i-zdGnCGM/0/Ti/IMG_0588_10_7Df-Ti.jpg "pogolumina > ● Mission Espada, San Antonio Missions N.H.P., TX USA
● 3/01/10 3:25PM sun/clouds, air temp: 15°C / 60°F
[IMAGE 4 of 4] Late winter/early spring nest maintenance. These Pogonomyrmex barbatus workers were slowly bringing loads of sand/soil up from the depths of their nest. They appeared to be utilizing their psammophores in some cases, and their mandibles alone, in others - depending on the moisture content of the soil they were transporting. It had rained the day before these images were captured, and much of the soil was quite moist and clumped - allowing it to be easily picked up and carried in the mandibles of these workers (like a clump of sticky rice can be picked up with chopsticks).")
![pogolumina > ● Anza-Borrego Desert S.P., Ocotillo Wells Vehicular Rec. Area, [San Diego Co], CA USA [el. 121 m / 398 ft] map location not yet available »
● 4/06/11 1:10PM overcast, breezy, air temp: 30°C / 86°F
[Image 1 of 2] P. anzensis habitat at the Ocotillo Wells Vehicular Recreation Area. Slope is covered with very large rocks, and is dotted with creosote bush (Larrea tridentada), and brittlebush (Encelia farinosa). Arrow indicates position of the only nest we found at this locality - adjacent to a large brittlebush plant.](http://www.pogolumina.net/NorthAmericanPogosbySpecies/Pogonomyrmex-anzensis/i-T4kvBQB/1/Ti/0625_11_60D-Ti.jpg "pogolumina > ● Anza-Borrego Desert S.P., Ocotillo Wells Vehicular Rec. Area, [San Diego Co], CA USA [el. 121 m / 398 ft] map location not yet available »
● 4/06/11 1:10PM overcast, breezy, air temp: 30°C / 86°F
[Image 1 of 2] P. anzensis habitat at the Ocotillo Wells Vehicular Recreation Area. Slope is covered with very large rocks, and is dotted with creosote bush (Larrea tridentada), and brittlebush (Encelia farinosa). Arrow indicates position of the only nest we found at this locality - adjacent to a large brittlebush plant.")
![pogolumina > ● Anza-Borrego Desert S.P., Ocotillo Wells Vehicular Rec. Area, [San Diego Co], CA USA [el. 121 m / 398 ft] map location not yet available »
● 4/06/11 1:20PM overcast, breezy, air temp: 30°C / 86°F
[Image 2 of 2] Close-up view of the P. anzensis nest area indicated in the previous image. The entrance itself was a cave-like vertical opening, located just under the tip of the white rock at the arrow's point. Ruler is 15 cm / 6 inches.](http://www.pogolumina.net/NorthAmericanPogosbySpecies/Pogonomyrmex-anzensis/i-NHVjzhd/1/Ti/0638_11_7D-Ti.jpg "pogolumina > ● Anza-Borrego Desert S.P., Ocotillo Wells Vehicular Rec. Area, [San Diego Co], CA USA [el. 121 m / 398 ft] map location not yet available »
● 4/06/11 1:20PM overcast, breezy, air temp: 30°C / 86°F
[Image 2 of 2] Close-up view of the P. anzensis nest area indicated in the previous image. The entrance itself was a cave-like vertical opening, located just under the tip of the white rock at the arrow's point. Ruler is 15 cm / 6 inches.")
![pogolumina > ● Anza-Borrego Desert S.P., near Pegleg Smith monument, [San Diego Co], CA USA [el. 209 m / 687 ft] map location not yet available »
● 4/09/11 4:33PM clear, breezy, air temp: 23°C / 74°F
[Image 1 of 2] Steep, rocky Pogonomyrmex anzensis habitat near the Pegleg Smith mounument, on the border of Anza-Borrego Desert State Park and Borrego Springs, California. Creosote bush (Larrea tridentada), and brittlebush (Encelai farinosa) were abundant here. P. anzensis workers were seen retrieving fallen brittlebush seeds from the ground, and transporting them back to the nest. Arrow indicates the location of one of the two nests we found at this locality.](http://www.pogolumina.net/NorthAmericanPogosbySpecies/Pogonomyrmex-anzensis/i-73t62QL/1/Ti/0779_11_60D-Ti.jpg "pogolumina > ● Anza-Borrego Desert S.P., near Pegleg Smith monument, [San Diego Co], CA USA [el. 209 m / 687 ft] map location not yet available »
● 4/09/11 4:33PM clear, breezy, air temp: 23°C / 74°F
[Image 1 of 2] Steep, rocky Pogonomyrmex anzensis habitat near the Pegleg Smith mounument, on the border of Anza-Borrego Desert State Park and Borrego Springs, California. Creosote bush (Larrea tridentada), and brittlebush (Encelai farinosa) were abundant here. P. anzensis workers were seen retrieving fallen brittlebush seeds from the ground, and transporting them back to the nest. Arrow indicates the location of one of the two nests we found at this locality.")
![pogolumina > ● Anza-Borrego Desert S.P., near Pegleg Smith monument, [San Diego Co], CA USA [el. 209 m / 687 ft] map location not yet available »
● 4/09/11 4:22PM clear, breezy, air temp: 23°C / 74°F
[Image 2 of 2] Close-up view of the entrance to the P. anzensis nest indicated in the previous image. Unlike the other two nests we saw, this one was not hidden by large rocks. A worker can be seen peering from the nest entrance in this natural-light image.](http://www.pogolumina.net/NorthAmericanPogosbySpecies/Pogonomyrmex-anzensis/i-Qd2SPxm/2/Ti/0767_11_7D-Ti.jpg "pogolumina > ● Anza-Borrego Desert S.P., near Pegleg Smith monument, [San Diego Co], CA USA [el. 209 m / 687 ft] map location not yet available »
● 4/09/11 4:22PM clear, breezy, air temp: 23°C / 74°F
[Image 2 of 2] Close-up view of the entrance to the P. anzensis nest indicated in the previous image. Unlike the other two nests we saw, this one was not hidden by large rocks. A worker can be seen peering from the nest entrance in this natural-light image.")
● Mission Espada, San Antonio Missions N.H.P., TX USA
● 3/01/10 3:25PM sun/clouds, air temp: 15°C / 60°F
● 3/01/10 3:25PM sun/clouds, air temp: 15°C / 60°F
[IMAGE 4 of 4] Late winter/early spring nest maintenance. These Pogonomyrmex barbatus workers were slowly bringing loads of sand/soil up from the depths of their nest. They appeared to be utilizing their psammophores in some cases, and their mandibles alone, in others - depending on the moisture content of the soil they were transporting. It had rained the day before these images were captured, and much of the soil was quite moist and clumped - allowing it to be easily picked up and carried in the mandibles of these workers (like a clump of sticky rice can be picked up with chopsticks).
![pogolumina > ● Mission Espada, San Antonio Missions N.H.P., TX USA
● 3/01/10 3:25PM sun/clouds, air temp: 15°C / 60°F
[IMAGE 4 of 4] Late winter/early spring nest maintenance. These Pogonomyrmex barbatus workers were slowly bringing loads of sand/soil up from the depths of their nest. They appeared to be utilizing their psammophores in some cases, and their mandibles alone, in others - depending on the moisture content of the soil they were transporting. It had rained the day before these images were captured, and much of the soil was quite moist and clumped - allowing it to be easily picked up and carried in the mandibles of these workers (like a clump of sticky rice can be picked up with chopsticks).](http://www.pogolumina.net/NorthAmericanPogosbyBehavior/Nests/i-zdGnCGM/0/M/IMG_0588_10_7Df-M.jpg "pogolumina > ● Mission Espada, San Antonio Missions N.H.P., TX USA
● 3/01/10 3:25PM sun/clouds, air temp: 15°C / 60°F
[IMAGE 4 of 4] Late winter/early spring nest maintenance. These Pogonomyrmex barbatus workers were slowly bringing loads of sand/soil up from the depths of their nest. They appeared to be utilizing their psammophores in some cases, and their mandibles alone, in others - depending on the moisture content of the soil they were transporting. It had rained the day before these images were captured, and much of the soil was quite moist and clumped - allowing it to be easily picked up and carried in the mandibles of these workers (like a clump of sticky rice can be picked up with chopsticks).")
● Mission Espada, San Antonio Missions N.H.P., TX USA
● 3/01/10 3:25PM sun/clouds, air temp: 15°C / 60°F
● 3/01/10 3:25PM sun/clouds, air temp: 15°C / 60°F
[IMAGE 4 of 4] Late winter/early spring nest maintenance. These Pogonomyrmex barbatus workers were slowly bringing loads of sand/soil up from the depths of their nest. They appeared to be utilizing their psammophores in some cases, and their mandibles alone, in others - depending on the moisture content of the soil they were transporting. It had rained the day before these images were captured, and much of the soil was quite moist and clumped - allowing it to be easily picked up and carried in the mandibles of these workers (like a clump of sticky rice can be picked up with chopsticks).
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