Pyrearinus is a genus of click beetle (family Elateridae).

As one of the members of the tribe Pyrophorini, all species of this genus have luminous organs on their abdomen;[2] among them, larvae of Pyrearinus termitilluminans [pt; species] (described from Emas National Park, Brazil) are responsible for so-called "luminous termite hill" known to human beings at least since 1850.

Brownish or black; some species have a bicolorous prothorax (lateral margins yellowish or reddish and discal region darker).

Female genitalia, bursa copulatrix more or less spiraled with a variable number of long spines; median oviduct with sclerotized plates.

Sexual dimorphism more or less accentuated, males with eyes larger than the females, and with longer antennae; in one species group (nyctolampis) the females have hind wings little shorter than usual.