Our insect of the week for August 10, 2026 is yet another ant. Yes, there are over 125 described species of ants from Illinois. No, I do not plan to show you all of them (at least for now *grin*). The ant you see here is Aphaenogaster tennesseensis. [HYMENOPTERA: Formicidae]. This ant was described by the Austrian entomologist Gustav Mayr in 1862. These ants are forest dwellers and mature nests are typically found in rotting wood. Workers are typically generalist scavengers and predators. Queens of this species are presumed to be temporary social parasites and invade the nests of related species (typically in the Aphaenogaster rudis species complex or the Aphaenogaster picea species complex). It is thought the queen typically rushes past ants guarding the entrance, locates the host queen and eliminates her. She then lays her eggs and the host species raise the offspring as if they were their siblings. Over time, the host species workers die off and the colony is firmly established.

Another fun fact about these ants is the workers often give off the scent of artificial grape soda (remember the old Nehi grape soda)? The chemical responsible for this odor is methyl anthranilate. Clearly, this is an ant species deserving much additional study.

This species is known from the following central Illinois counties: Marshall, Mason, Peoria, and Tazewell. The ant in the photograph was collected in Peoria County.