Photo: gailhampshire / CC BY 2.0

Bombus vestalis

Vestal Cuckoo Bumblebee

A large cuckoo bumblebee (queen up to 21 mm) belonging to the subgenus Psithyrus, with no worker caste and no pollen-collecting apparatus. It is predominantly black with an orange-yellow collar, a patch of yellow hairs on the third tergite, and white hairs on the fifth tergite. The wings are distinctly dark-tinted. It is a brood parasite of Bombus terrestris (Buff-tailed Bumblebee): the female invades a host nest, kills or subdues the resident queen, and forces the host workers to rear her offspring. It occurs across most of Europe and in Switzerland is widespread from lowlands to montane elevations wherever its host is found, flying from March to September. It is classified as Least Concern (LC).