Kinds of Ants

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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?

 

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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)

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Once again, these ants are found in firewood.

At first glance the workers look somewhat like Camponotus pennsylvanicus carpenter ant workers. This worker is in the 6.5-7 mm range.

The surprise comes when an alate comes crawling out of a tunnel. At this scale you probably still can't see the difference.

That alate is much smaller than an alate of of a Camponotus pennsylvanicus.

Looking closely at a front on view of a worker's head, you find that they lack hairs on the genae and have few on the clypeus. These are Camponotus nearcticus workers.

I was a bit surprised, because in the area I was collecting I had typically encountered C. nearcticus with a brown-red mesosoma, like this one at BugGuide. Just goes to show, once again, that color is not a useful guide to identification in ants.

According to Hansen, this species is spread throughout the eastern United States and across the northern U.S and southern Canada all the way to the West Coast. They are even found in certain parts of Arizona, although not in the low desert.

The alates are apparently reared in the fall and overwinter in the nest, as with other carpenter ants. I did not find any larvae or other immatures.

Their biology seems to be similar to that of other carpenter ants, but they have not been studied extensively.

Have you ever encountered Camponotus nearcticus?