48 spp. in our area, all in the subg. Neobrachinus
; >300 spp. in 9 subgenera worldwide(1)
Canada 10 spp.(2)
, RI 12(3)
, FL 19(4)
Medium-sized beetles with dark (blue, green, or blackish) elytra that contrast strongly with orange head and pronotum; some are flightless(5)
revision of N. Amer. spp. in(6)
key to the 16 SC spp. in(5)
worldwide (poorly represented in Australasia); throughout NA, much more diverse in the south (do not range north of 50N in the west and 45N in the east)(7)
under loose bark, rocks, boards, on ground in open at night; usually associated with floodplains, edges of temporary ponds
larvae are parasitoids of aquatic beetle pupae and scavenge body of host after its death
Eggs laid singly in mud cells made on plants, rocks. Larvae have reduced legs and pupate inside the host.
Adults have chemical defenses, ejecting toxic, foul-smelling gases from their abdomen with a loud popping sound. The explosive brew is composed of hydrogen peroxide, hydroquinone, and catalytic enzymes.