Definition
The *genus Psithyrus* consists of cuckoo bumblebees. These bees are obligate social parasites within nests of bumblebees (*Bombus*). Females of *Psithyrus* species lack a worker caste. They invade *Bombus* nests, kill or subdue the resident queen, and manipulate the *Bombus* workers to raise their offspring. They are kleptoparasites, stealing resources instead of gathering them. Think of them as the usurpers of the bee world. They rely on the hard work of others. 👑🐝