Pogonomyrmex barbatus
Pogonomyrmex barbatus, the Red Harvester Ant, is fairly common throughout Arizona's deserts. They usually prefer somewhat moister deserts than their close relative Pogonomyrmex rugosus.

This is not a hard and fast rule, however - there are areas in which the two species overlap. Indeed, in some of these areas an interesting hybridization occurs between the two species. These harvester ants mate in large aggregations. A single female mates with many males. In addition to mating with males of her own species, females of Pogonomyrmex barbatus will mate with males of Pogonomyrmex rugosus, and vice versa.

Recent research indicates that the queens in these zones of hybridization, while producing hybrid workers, do not produce hybrid queens. This means that the workers are hybrids of P. rugosus and P. barbatus, but the sexuals (queens and winged males) are "purebreds". If the workers of an ant nest can be thought of as the superorganism's body, and the sexuals can be thought of as the superorganism's genetic material, it is as though an animal with the body of a mule has the genetic make up of a horse. Very cool indeed.

Pogonomyrmex barbatus' nest entrances are often surrounded by a disk of bare ground - sometimes the disk is covered with gravel, sometimes not. If plants grow up inside of the disk of clear ground, the ants will chew at the plants until the plants die.

There are a variety of ideas about why the ants create these disks - that they are useful in temperature regulation, that the clear areas make it harder for predators to hide, that they somehow make the ant's territory easier to mark. I don't know what the real answer is, though.

Pogonomyrmex barbatus are seed eating ants. Like many of the other Pogonomyrmex harvester ants, they have a powerful sting which they are not shy about using. Their sting is quite painful and best avoided. In the evening, a few Pogonomyrmex barbatus workers will usually seal the nest entrance with gravel and twigs to keep nighttime intruders out of the nest. The ants in the photos below are bringing pebbles over to the nest entrance to block it off. Often one or two of the workers will end up on the outside of the nest entrance after closing it. Below are a few photos of workers carrying pebbles over to seal off the nest.


  

Click on the images below to see a larger version

Pogonomyrmex barbatus worker dragging a large pebble over to her nest. They often block their nest entrances overnight.
Pogonomyrmex barbatus worker dragging a large pebble over to her nest. They often block their nest entrances overnight.
Pogonomyrmex barbatus worker.
Pogonomyrmex barbatus worker.
Pogonomyrmex barbatus worker carrying excavated soil out of her nest.
Pogonomyrmex barbatus worker carrying excavated soil out of her nest.
Fierce territorial battles between Pogonomyrmex barbatus nests are fairly common. Here a smaller Dorymyrmex insanus ant is taking advantage of two wounded Pogonomyrmex barbatus.
Fierce territorial battles between Pogonomyrmex barbatus nests are fairly common. Here a smaller Dorymyrmex insanus ant is taking advantage of two wounded Pogonomyrmex barbatus.
Myrmecocystus (honeypot ants) will often hang around a Pogonomyrmex nest. The Myrmecocystus will 'frisk' Pogonomyrmex workers returning to the nest. If the Pogonomyrmex is carrying a seed, the Myrmecocystus will let it pass. If the Pogo is carrying insect prey, though, the Myrmecocystus will steal it away.
Myrmecocystus (honeypot ants) will often hang around a Pogonomyrmex nest. The Myrmecocystus will 'frisk' Pogonomyrmex workers returning to the nest. If the Pogonomyrmex is carrying a seed, the Myrmecocystus will let it pass. If the Pogo is carrying insect prey, though, the Myrmecocystus will steal it away.
Myrmecocystus (honeypot ants) will often hang around a Pogonomyrmex nest. The Myrmecocystus will 'frisk' Pogonomyrmex workers returning to the nest. If the Pogonomyrmex is carrying a seed, the Myrmecocystus will let it pass. If the Pogo is carrying insect prey, though, the Myrmecocystus will steal it away.
Myrmecocystus (honeypot ants) will often hang around a Pogonomyrmex nest. The Myrmecocystus will 'frisk' Pogonomyrmex workers returning to the nest. If the Pogonomyrmex is carrying a seed, the Myrmecocystus will let it pass. If the Pogo is carrying insect prey, though, the Myrmecocystus will steal it away.
Myrmecocystus (honeypot ants) will often hang around a Pogonomyrmex nest. The Myrmecocystus will 'frisk' Pogonomyrmex workers returning to the nest. If the Pogonomyrmex is carrying a seed, the Myrmecocystus will let it pass. If the Pogo is carrying insect prey, though, the Myrmecocystus will steal it away. The Pogonomyrmex nest entrance is behind the Myrmecocystus in this photo.
Myrmecocystus (honeypot ants) will often hang around a Pogonomyrmex nest. The Myrmecocystus will 'frisk' Pogonomyrmex workers returning to the nest. If the Pogonomyrmex is carrying a seed, the Myrmecocystus will let it pass. If the Pogo is carrying insect prey, though, the Myrmecocystus will steal it away. The Pogonomyrmex nest entrance is behind the Myrmecocystus in this photo.
Pogonomyrmex barbatus chewing into a mesquite pod. They enjoy eating the sweet lining of the bean pods.
Pogonomyrmex barbatus chewing into a mesquite pod. They enjoy eating the sweet lining of the bean pods.
Ants often have uninvited guests that stay in their nests. This Tenebrionid beetle larva is related to Mealworm Beetles. It was in side a Pogonomyrmex barbatus nest, probably living on the ants' seed stores.
Ants often have uninvited guests that stay in their nests. This Tenebrionid beetle larva is related to Mealworm Beetles. It was in side a Pogonomyrmex barbatus nest, probably living on the ants' seed stores.