Appearance
The body is mainly reddish-brown or yellow-brown. The head is yellow, quite large and inflated-looking, with a kind of bubble at the front, narrow cheeks and short antennae. The large eyes are reddish. When in resting position the abdomen is usually folded forward.The adults grow up to 8–13 millimetres long and can be encountered from May through September, feeding on nectar or pollen of various Asteraceae species, Apiaceae species, Parsley "Petroselinum sp". and Rosaceae species.

Food
Their larvae are endoparasites of bumble bees of the genus "Bombus". They pupate and overwinter in their victims.References:
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