So far as known, all larvae are specialized predators. Larvae of most genera enter the nests of wild bees, where they consume both immature bees and the provisions of one or more cells. Those of some Meloinae, including most Epicauta spp. Triungulin larvae of Nemognathinae found in flowers or attached to the hairs of bees are sometimes mistaken for those of Rhipiphoridae. In both groups, the body is navicular and heavily sclerotized and there is a definite pattern of setation.
Larval development is hypermetamorphic, with four distinct phases.
In Meloinae the fully fed FG larva generally excavates a chamber apart from the feeding site. In this phase the musculature undergoes profound degeneration and respiration is reduced to an extremely low level, permitting survival for more than a year, if necessary. Nemognathinae are unusual in that the SG larva and following pupa and adult are encapsulated by the cast but intact skins of the last instar FG larva and the C larva. Several alternative developmental pathways have been identified. Rarely, a larva pupates directly from the C phase.