Acrobats ants and frass

A few times every season I’ll have encounters with these acrobat ants. Usually they’ll end up in my schedule erroneously as a service call for carpenter ants because often times when they’re actually infesting a structure the homeowner will report that they’re pushing out debris from their nest site similar to what carpenter ants do.

Are acrobat ants a related species to the common black carpenter ant? The answer is no, these ants belong to an entirely different genus called Crematogaster. There are about a half dozen species in the US and they range in size from 1/16 to 1/8 inch long, brownish black in color, though there are some multicolored species too. They are monomorphic (all one size) with two nodes separating the thorax and abdominal segments. Carpenter ants are polymorphic with a single node. One key identifier of this species is their unique ‘heart shaped’ abdomen.

Acrobat ants will trail extensively when foraging. Inside a structure, they may infest water damaged wood or rigid foam insulation. I’ve seen this occur quite often and the signs my initially point to a carpenter ant infestation, but the ‘frass’ that acrobat ants expel from their nests is much finer in texture that what is typical for carpenter ants.

Why are they called acrobat ants you ask? When they are disturbed, (as in attacking their nest!) they will scurry about raising their abdomen over their thorax. Very acrobatic indeed!

Photo: Tom Allen [CC BY-SA 2.0, GFDL or CC-BY-SA-3.0], via Wikimedia Commons