Photo: Arnstein Staverløkk / NINA / CC BY 3.0

Sphecodes monilicornis

Box-headed Blood Bee

A medium-sized cleptoparasitic blood bee (8–11 mm) with a black head and thorax, a red abdomen (often with darkened tergites), and a distinctive box-shaped head when viewed from above. The hind tibial hairs are whitish, distinguishing it from similar species. It is a cleptoparasite of larger Halictus species, especially Halictus rubicundus, Halictus sexcinctus, and Halictus quadricinctus. Females search for host nests in bare ground, laying eggs in the provisioned brood cells. In Switzerland it is widespread in warm open habitats from lowlands to montane elevations. Females fly from March to September, males from July to October. Swiss Red List: Least Concern (LC).