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What is a cuckoo bumblebee?
A
cuckoo bumblebee, like the bird it is named after, lays its eggs in another
bumblebees nest and leaves the workers of that nest to rear the young. Of
course the eggs she lays are either females or males (there are no queens). The cuckoo females
emerge from hibernation in late spring or early summer, much later than
ordinary bumblebee queens. So by the time the cuckoo females have emerged the
bumblebee queens will have already established their nests. Cuckoo bumblebees usually
have the same pattern of hair colour as the bumblebees' nests they lay
in.
Differences between cuckoo bumblebees and queen and worker bumblebees
The cuckoo differs
physically from ordinary queen bumblebee in that:
- She has no pollen basket on her rear legs
- Does not exude wax
from between her abdominal segments
- Is slightly less hairy than ordinary
bumblebees
- All species have shortish tongues.
- They have a much harder
body than normal bumblebees
- And because no wax is exuded there are no weak
points between the abdominal segments, so if there is a fight between a cuckoo
and another worker or queen it is almost impossible for the queen or worker to
force her sting into the cuckoo body
- They also tend to have a more pointed abdomen, and becase they are less hairy the tip of the abdomen is often visible.
It is thought
that the cuckoo females locate an established nest by smell. She may go right in
and sting the existing queen to death then lay eggs, or she may sneak in the
nest and hide for a few days until she smells the same as the nest, then lay
her eggs. Whatever method she uses it spells the beginning of the end for the
nest because the cuckoo larvae consume resources but contribute nothing to the
nest.
It has been decided to rename the genus of cuckoo bumblebees from Psithyrus to Bombus. |
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Female |
Male |
Bombus/Psithyrus rupestris
Rare and not recorded in Scotland. She takes over the nests of Bombus lapidarius. Has darker wings than Lapidarius. Body lengths, female 22 mm, male 16 mm. |
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Female |
Male |
Bombus/Psithyrus sylvestris (Forest cuckoo bumblebee)
Common and takes over the nests of Bombus pratorum and jonellus. Body lengths, female 15 mm, male 14 mm. Males tend to patrol mating circuits within 1 m of the ground. |
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Female |
Male |
Bombus/Psithyrus bohemicus
Common and takes over the nests of Bombus lucorum. Body lengths, female 19 mm, male 16 mm. |
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Female |
Male |
Bombus/Psithyrus vestalis, (Southern cuckoo bumblebee)
More common in the south, and not recorded in Scotland*. She takes over the nests of Bombus terrestris. Body lengths, female 21 mm, male 16 mm.
*It has recently been confirmed that this bumblebee was found in southern Scotland in the summer of 2009. |
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Female |
Male |
Bombus/Psithyrus barbutellus
Common and takes over the nests of Bombus hortorum. Body lengths, female 18 mm, male 15 mm. |
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Female |
Male, light form |
Male dark form |
Bombus/Psithyrus campestris (Field cuckoo bumblebee)
Common and takes over the nests of Bombus pascuorum. Body lengths, female 18 mm, male 15 mm. |
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Many of the images on this page were taken from Prys-Jones and Corbet's excellent book Bumblebees. As you can see the cuckoos resemble the species whose nests they take over.
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(C) Copyright 1997 - 2012 |
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