The ants we want to Identify are about 1/2" in length. We are in central Illinois. They are living in an old pile of wood planks. They are black, red, gray (head, thorax, abdomen). Any help would be great.
Thanks for your question! Although a picture would help to give you a positive identification, it is likely that you are looking at a member of the genus Camponotus. Members of this genus will typically be among the largest ants encountered in North America and Europe (and many other places; in Southeast Asia they have a truly giant species, see a previous post on giant ants ). These ants often live in rotting wood, including wood that has fallen, and rotten sections in living trees. Some species even live in rotting sections of people's houses! The ants commonly called "Carpenter Ants" belong to this genus, but the species in your area that lives up to this name, Camponotus pennsylvanicus is all black, so it's likely you're looking at a species that prefers the habitat in which you found it.
Based on your location and the description you gave, a likely candidate is Camponotus chromaiodes . But we encourage you to brows the Ants of Illinois page and the Ants of Missouri page to see if you can find a better match!
Hope this helps! You're welcome to send us pictures if you want a more positive identification, or if you have any further questions.
Jesse Czekanski-Moir & the AntAsk Team