Winter firefly (Ellychnia corrusca) is the most common diurnal firefly, also called lightning bug, in Minnesota. It is medium-sized for a firefly but much larger than other species within its genus. Unlike most fireflies it has no bioluminescent organs and is active during the day. The common name reflects the fact that it overwinters as an adult. On warm, sunny, winter days an individual might be seen on a tree trunk wandering a short distance from its wintering spot.
This species is identified by the size, minute hairs on the forewings, and distinctive “parentheses” marking on the thoracic shield.