Pogolumina - Pogonomyrmex Harvester Ants of North America : Photo Keywords : ants : <span class="captionImageInfo"> ● Berg Ln / Cooley Rd, Bend [Deschutes Co], OR USA [el. 1060 m / 3478 ft]</span> <a href="http://maps.google.com/maps/ms?ie=UTF8&hl=en&t=h&msa=0&msid=100103460138962878270.00047e2eb40175fc7957d&ll=44.10765,-121.302417&spn=0.172562,0.291824&z=11&source=embed"><span class="mapLink">view location in Google Maps »</span></a>
<span class="captionImageInfo"> ● 7/19/09 7:16PM sunny, air temp: 28°C / 83°F</span>
<div class="captionImageMain">[IMAGE 2 of 2] This very rough-looking (this image has not been over-sharpened) <a href="http://www.davidlouisquinn.com/pogolumina_PsalinusInfo.htm"><span class="glossLinkSm"><em>Pogonomyrmex salinus</em></span></a> worker was imaged while gnawing on the femur of a large grasshopper leg, in central Oregon. As can be seen here, a good portion of the lower marginal area has been broken away by the ant's mandibles. The heavier medial area of the leg (with raised chevron-like ridges, and surrounded by the thick 'carinula') was apparently too tough for this determined ant, and she seemed unable to make any more progress. We believe the Pogo was trying to separate this large object into easily transportable pieces (the tibia was still attached, so the grasshopper leg was more than twice the length as can be seen in these images). <span class ="footnoteTag">[scroll down for additional notes/references]</span>
<div class="captionRefFootnote">ADDITIONAL NOTES/REFERENCES:
<em>Because they are referred to as harvester ants, Pogos are often thought of as strict granivores (feeding only on grains and seeds). Though they do collect great quantities of <a href="http://www.davidlouisquinn.com/pogolumina_feedingInfo.htm"><span class="glossLinkSm">plant-based nutritional resources</span></a>, they are also known (to a lesser degree) to scavenge arthropod carrion (dead insects, spiders, etc) in sometimes significant amounts.
The degree to which <a href="http://www.davidlouisquinn.com/pogolumina_PogonomyrmexInfo.htm"><span class="glossLinkSm">Pogonomyrmex ants</span></a> utilize this type of food, varies from species to species, and on many other factors, including variation coinciding with seasonal changes, or local events like rainfall.
In some species, such as P. montanus, insects and insect parts may make up more than 25% of the total food intake for the colony. One study of Pogonomyrmex salinus in southeastern Idaho, found that only 2% of returning foragers carried insects or dung (the authors add; "Although insects were included in only 2% of the foraging trips, they accounted for 12% of the food weight per unit trip".
While most of this arthropod/insect food is apparently scavenged from already-dead creatures, Pogonomyrmex ants (and other ant species) are famous for sometimes preying on live termites - especially during the termite's mating swarms. Also, Pogonomyrmex rugosus has been observed to prey on live grass cicadas (Beameria vanosa) as they emerge from the ground in Spring.
Clark & Blom observed <a href="http://www.davidlouisquinn.com/pogolumina_PsalinusInfo.htm"><span class="glossLinkSm">Pogonomyrmex salinus</span></a> workers feeding on the carcass of a sagebrush lizard (Sceloporus graciosus), in Idaho - it is is not known if the ants killed the lizard as well. Other Pogos have also been been known to feed on already-dead reptiles and small mammals (small bits of flesh are removed by the ants, and carried back to the nest). Dead mammals and reptiles are not known to serve as a major source of food for Pogos.
·Clark, W.H. & P.E. Blum. 1991. Observations of Ants (Hymenoptera: Formicidae: Myrmicinae, Formicinae, Dolichorderinae) Utilizing Carrion. The Southwestern Naturalist Vol.36, No.1, March 1991
·Jorgensen C.D. & Porter, S.D. 1982. Foraging Behavior of Pogonomyrmex owyheei in Southeast Idaho. Environmental Entomology, Vol. 11, No. 2, April 1982
·MacKay, W.P. 1981. A Comparison of Nest Phenologies of Three Species of Pogonomyrmex Harvester Ants (Hymenoptera: Formicidae). Psyche, Vol. 88, No. 1-2, 1981
·Whitford, W.G & E. Jackson. 2007. Seed Harvester Ants (Pogonomyrmex rugosus) as "Pulse" Predators. Journal of Arid Environments 70 (2007) 549-552