As we start 2026, I thought it might be appropriate to focus on some of the more colorful butterflies found in central Illinois. Personally, I am already looking forward to spring and the chance to observe many more insects.

Our insect of the week for January 5, 2026 is one of my favorite butterflies – the zebra swallowtail (Eurytides marcellus). It was described by Pieter Cramer in 1777.

Adults can be observed from late March through August in central Illinois. The host plant is pawpaw and males will patrol near host plants. They are very fast fliers. Males can also be observed puddling (which is where I first encountered them in Mason County). Puddling is where the butterflies congregate on moist sand and gravel to lap up salts and amino acids. Adults are also attracted to rotting fruit and mammalian urine. Caterpillars are cannibalistic so females lay eggs individually on the host plant leaves or trunk. Caterpillars ingest neurotoxic chemicals from the host plant (specifically annonaceous acetogenins – a type of polyketide). These chemicals are retained in the larval, pupal, and adult stages and may help deter bird predation.

I can still recall the first ones I encountered in central Illinois in the 1970’s. It was hard to believe such a marvelous creature could be found here. The specimen shown here was collected (and photographed) in Peoria county by Frank Hitchell.