There are more than 850 species of nomad bee (Nomada sp.) worldwide, more than 280 species in North America. Like other cuckoo bees (subfamily Nomadinae), nomad bees do not construct nests, but lay their eggs in the nests of ground-nesting bees. One to four eggs are laid in the cell wall of the host nest. The larvae have large, outward-facing, scissor-like mandibles. The first larva to emerge destroys all the other eggs, both those of the host and those of its own siblings. It consumes the pollen provisioned by its host, and emerges as an adult the same time as the host adults emerge.
Nomad bees are usually black, black and red, or entirely red, with yellow, white, and/or red markings. Many species have red legs. The genus Nomada includes the only bees in North America that are entirely red. They have short, thin, and inconspicuous hairs on the body and no pollen-collecting hairs (scopa) on the hind legs. They look more like wasps than a bees.