Gypsy cuckoo bumblebee (Bombus bohemicus)
A widespread and common cuckoo bumblebee, particularly in the north. Like all cuckoo species, they do not collect pollen for their offspring (and so have no pollen baskets or worker caste), but instead take over the nests of the White-tailed bumblebee complex (White-tailed bumblebee, Bombus lucorum; Northern white-tailed bumblebee, Bombus magnus; Cryptic bumblebee, Bombus cryptarum). A variable species, it has darkened wings and always has a yellow collar on the thorax and a white tail with a small pale yellow patch on each side of the abdomen, at the front of the tail. Males often have a second yellow band at the rear of the thorax.
The Southern cuckoo bumblebee (Bombus vestalis) is very similar, but has more extensive yellow side-patches. Examination of the genital capsule is useful for accurate identification of males, which can also be determined by the ratio of the 3rd and 5th antennal segments (equally long in Gypsy cuckoos, 5th longer than 3rd in Southern cuckoos). Females can be identified by checking the degree of pitting on the underside of the tail (6th abdominal sternite) – heavily pitted and not shining in Southern cuckoos, smooth and shining in Gypsy cuckoos.
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