Kinds of Ants

Now that the blog is all cleaned up, it is time to get out and spend more time looking for and watching ants.

dorymyrmex-insanus-firstThe very first colony I found turned out to be a common ant, but one that I haven't documented before. Do you recognize it?

Dorymyrmex-insanus-2-active

After checking a specimen under the scope, it was evident these were in the genus Dorymyrmex because there was a protruding bump on the propodeum, which gives them the name "cone" or "pyramid" ant.

aaa-dorymyrmex-on-sandmat-close

Here in Arizona, we regularly see another species in the same genus, Dorymyrmex bicolor, which has a brownish-red head and mesosoma.

dorymyrmex-insanus-close

The dark-colored western cone ants are generally called Dorymyrmex insanus, although the scientific name has been changing "crazily" over a century, plus the genus seriously needs to be revised (Navajo Nature).

The common name isn't much better. As indicated by the "insane" species name, these ants are commonly called "crazy ants" because they move erratically. The name crazy ant causes confusion, however, because there are now invasive/pest species with similar names, such as Nylanderia fulva (the tawny or Rasberry crazy ant) or Paratrechina longicornis (the longhorn crazy ant). Perhaps we should stick to cone ants?

Dorymyrmex insanus are known to inhabit dry, open areas like the Sonoran desert. They live in small colonies (roughly 2000-3000 workers) in the soil. Like many other kinds of ants, they feed on scavenged insects/dead things and also tend aphids for honeydew.

In his book Adventures Among Ants (reviewed here), Mark Moffett noted that cone ants have been observed grooming harvester ants. Generally ants fight or avoid each other when they encounter ants of a different species, but these cone ants were photographed licking a much-larger Pogonomyrmex worker and leaving it unharmed. James Trager calls cone ants the "cleaner fishes" of the ant world. You can see his photograph at BugGuide.

Have you ever seen Dorymyrmex insanus ants? Where did you find them?

Reference:  Snelling, Roy R. 1995. Systematics of the Nearctic genus Dorymyrmex (Hymenoptera: Formicidae). Contributions in Science (Los Angeles) 454:1-14.  (Available as free .pdf)

4 Comments

In a recent trip to western New York, I noticed a trend. Whenever I found an ant colony (flipping rocks looking for bait for a family member who likes to fish)...

cornfield-ants

an ant colony like these cornfield ants...

cornfield-nearby-thief-ant

I found thief ants.

thief-and-crematogaster

Everywhere.

lasius-claviger-group-1

Take these Lasius.

 

lasius-claviger-group-2

Can you see the thief ants?

lsius-claviger-group-4

Let me give you clues. The thief ant is in the top right of first photo, near cluster of three larvae in second photo, and going into the tunnel just left of center in the last photograph.

Thief ants are named for their tendency to live with or near other ant colonies and then steal food from their "hosts."

They can also be found living in separate colonies.

colony-of-thief-ants

Some of the thief ant colonies I found living by themselves were quite large.

 

thief-ant-large-single-colony-close

Looks like quite a few new thief ants are on the way.

According to School of Ants, thief ants are distributed throughout the United States (although they don't show any records for New York State on the map). I had never noticed thief ants when I looked for ant colonies in that location in the past. I know my vision hasn't gotten any better, so that isn't it. It seems like thief ants have gotten a lot more numerous there.

Have you noticed more colonies of thief ants where you study ants? Do you think this a trend or a random happenstance?

 

2 Comments

What is this ant doing out and about this time of year? It is December, after all.

There hasn't been rain for weeks.

My son found her walking on the driveway.

She's definitely a Solenopsis because the antennal club is two segments, not three. It seems rather odd, but other species of fire ants are thought to have nuptial flights throughout the year, not just the typical ones that occur on warm, humid days in the spring or summer.

Looking back, I see that I found a single queen that was probably the same species under a rock in November of 2009 (see, blog posts are useful sometimes).

They both look like Solenopsis amblychila based on Trager's (1991) description:  the queen has no clypeal teeth and the shape of the head is cordate when viewed face on.

As to what she is doing, my best guess that a mated queen would be trying to enter an established nest this time of year.  What do you think?

Trager, J. C. 1991. A revision of the fire ants, Solenopsis geminata group (Hymenoptera: Formicidae: Myrmicinae). Journal of the New York Entomological Society, 99:141-198. (.pdf available here)