Winter Firefly

Ellychnia corrusca is a medium to large beetle, with adults that are 9 to 18 mm (0.4 to 0.7 in) long. The head shield, or pronotum, has a black, rounded central mark bordered by yellow and pink on both sides. The pronotum has black edges. The wing covers, or elytra, are dark and have fine hairs that can seem greenish or golden in certain light conditions. Adult E. corrusca do not have lanterns. The last abdominal segment on the underside of the adults differs between males and females. On males, it is small and rounded, and on females it is larger and triangular with a small central notch. The larvae are dark with pink sides and thick, bristled bodies. They grow up to 17 mm (0.67 in) long. Each larva has two lanterns that glow.

Ellychnia corrusca is common throughout the United States, Mexico, and Canada east of the Rocky Mountains.

Ellychnia corrusca possesses lucibufagins (LBGs), which are defense chemicals against predators. However, summer-active fireflies of the Photuris genus hunt prey containing lucibufagins. Scientists propose that in order to defend themselves, E. corrusca alters its reproduction timeline to help it escape Photuris fireflies. E. corrusca overwinters and reproduces in the spring, which therefore reduces its overlap with Photuris that are active during the summer. In an experiment done with E. corrusca and a mealworm beetle control, the Photuris are drawn to the LBGs emitted by E. corrusca. In fact, mealworm beetles that did not have LBGs failed to generate a response from Photuris. When mealworm beetles were treated with LBGs, however, Photuris did consume them. In order to avoid predation, E. corrusca had a phenological shift to winter and spring reproduction and a shift to the daytime.