Psithyrus

Subgenus of bees

Cuckoo bumblebees are members of the subgenus Psithyrus in the bumblebee genus Bombus. Until recently, the 28 species of Psithyrus were considered to constitute a separate genus. They are a specialized socially parasitic lineage which parasitises the nests of 'true' bumblebees, resulting in the loss of the ability to collect pollen and establish their own nests. Cuckoo bumblebees do not create a worker caste and produce only male and female reproductives. They are considered inquilines in the colonies of 'true' bumblebees.

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