Our insect of the week (for June 8, 2026) is one more fossil from Pit 11 near Braidwood, Illinois in my collection. I’m just trying to give a hint of the diversity of insects which were alive during the Carboniferous in what we now call Illinois. I will delve into more modern insects in coming weeks. I realize this one did not photograph that well (even with stacking software). I am also relying on the identification made by a paleo-entomologist some time ago.

I present to you Eucaenus ovalis Scudder, 1885 [Protorthoptera: Eucaenidae]. The order Protorthoptera is somewhat of a collection basket for insects which don’t seem to fit elsewhere in our classification scheme. Technically, this order is paraphyletic (meaning there is no commonly accepted single character defining this entire group). For contrast, the beetles (order Coleoptera) have a hardened fore wing (called an elytra) in their adult stage. They also have a subelytral cavity on the dorsum of their abdomen where they fit their folded hind wings. There is no commonly accepted single character for the order Protorthoptera. It is likely this order will be divided into other orders as we learn more about these insects.

This insect lived about 307 – 311 million years ago. It represents one of the first group of insects which developed flight. It is potentially an early relative of grasshoppers and crickets. Fossils of this species are known only from the Mazon Creek fossil beds. At the time, this part of what we now call Illinois was a tropical river delta dominated by lycopsid trees and seed ferns. Vastly different from what we presently observe in Illinois. This fossil is preserved as a concretion (iron carbonate). If you are interested in seeing or learning more about insect diversity in the Carboniferous of Illinois, please contact me.