Diurnal Firefly
Pyropyga nigricans
This beetle was observed in the riparian habitat along Mesquite Wash and its confluence with Sycamore Creek, Maricopa Co., Arizona. Aug. 2009. Identification was provided by Joe Cicero.
Fireflies are not true flies at all, but rather beetles. Most species have dark elytra (the first pair of wings hardened into a protective shell) that are leathery in texture. In the Sonoran Desert most firefly species are restricted to riparian habitats with denser vegetation and higher productivity. Species that fly and light up in flight are mostly absent. Quite a number of species have luminescent organs in the larval stage or as larva-form adults (glowworms). One of the most common species is the Diurnal Firefly, which has no luminescence at all, i.e. a firefly with no lights.
The Diurnal Firefly has an immature grub form that lives on the soil beneath debris and that actively hunts for small invertebrates. Finding these larvae in the field and rearing them would help to identify the precise trophic relationship played by these interesting beetles. This beetle is widespread in mesic habitats in North America.