Masked Bee (Genus: Hylaeus)
Over 500 species in this genus. Generally small, black and yellow/white wasp-like species. The resemblance to wasps is enhanced by the absence of a scopa, which is atypical among bees.
Hylaeus carry pollen in the crop, rather than externally, and regurgitate it into the cell where it will be used as larval food. Like most colletids, the liquid provisions are sealed inside a membranous cellophane-like cell lining. Nests are typically in dead twigs or plant stems, or other similarly small natural cavities, rather than constructing or excavating their own nests as in many other bees.
Some species are consiered vulnerable or endangered.