Re Bombus: 

> Most of the parasites are in what is called the subgenus Psithyrus; females of this subgenus lack the pollen-gathering and pollen-manipulating structures characteristic of other Bombus, and the apex of the metasoma, pointed and curled downward, houses a powerful sting. The female social parasite dominates or kills the host queen and may become, in essence, the queen of a colony consisting of herself and workers of the host species (Michener 2010).

Social or not? This is not simply a cuckoo bee which sneaks in and lays eggs, this one moves in and takes over. I have often wondered if the origin of social bees could be something like that ...

PLB

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