Fireflies are generally compressed, soft-bodied beetles with a shield-like pronotum that conceals the head. Adults of luminescent genera cast their familiar glow on warm summer evenings, while those of many "lightless" species are day-active, on the wing or on vegetation.

For identification of fireflies from eastern Canada and the adjacent United States please see:
Luk, S.P.L., Marshall, S.A., and Branham, M.A. 2011. The fireflies of Ontario (Coleoptera: Lampyridae). Canadian Journal of Arthropod Identification, 16. doi: 10:3752/cjai.2011.16. Available from http://www.biology.ualberta.ca/bsc/ejournal/lmb_16/lmb_16.html