Our insect of the week for July 20, 2026 is the ant, Trachymyrmex septentrionalis. [HYMENOPTERA: Formicidae]. This ant was described by the American naturalist Henry McCook in 1881. This is the northern most species in the ant tribe Attini – the fungus growing ants. Yes, our second Illinois ant being featured is a farmer. Like their relatives, this species cuts leaves and carries them underground where they grow a fungus. They then eat parts of thsi fungus.

Colonies are relatively small and are often noticed in spring and fall when they are expanding their nest. The soil is often depposited in a crescent shaped mound. They are only founf in sandy soil in central Illinois (specifically Mason County). I have observed them on a number of field trips to various sandy parts of the county. The specimen in the photograph was collected in Mason County. The photo is a stacked composite of a number of images and was taken by me in 2026.

I have also included a photo of the worker ant in lateral view. Although they are tiny, I find these to be amazing animals. The fact that we have fungus growing ants in central Illinois continues to astound me.