Our insect of the week for March 9, 2026 is Acharia stimulea, the Saddleback Caterpillar moth. [LEPIDOPTERA: Limacodidae] It was described by James Clemens (an American entomologist) in 1860.

We featured a related species, Lithacodes fasciola, as our insect of the week for July 28, 2025.

This moth is typically recognized by its larval phase (caterpillar). Parts of the body are lime green with a dark marking at the center (surounded by a white ring). This is where the common name derives as it resembles a saddle. I do not recommend picking up or toughing a caterpillar as they posess hollow spines. When broken, an attachd gland secretes venom. When the caterpillar transforms into the pupal stage, it incorporates these spines as part of the cocoon (further defending against predators).

Adults typically fly in July and August in central Illinois and may be attraced to light sources at night.

Although this species is known from central Illinois, members of the family are more commonly encountered in central America. Yes, I have observed relatives in Belize.

The specimen shown in the photo was collected and photographed by Frank Hitchell in Peoria County, Illinois.