Cuckoo bumblebees

On this page, what is a cuckoo bumblebee? - differences between cuckoo bumblebees and queen and worker bumblebees. - U. K. cuckoo bumblebees - a whole lot more What is a cuckoo bumblebee? A cuckoo bumblebee, like the bird it is named after, lays its eggs in another bumblebees 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 exoskeleton than normal bumblebees

Cuckoos have a longer sting than queen and worker 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 because 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. Cuckoo behaviour Cuckoo bumblebees do not forage as industriously as workers or queen bumblebees as they have no-one to provide food for but themselves. In fact their behaviour, before entering an established nest, resembles bumblebee males. They drink some nectar and then just laze around until they are hungry enough to drink more. U K cuckoo bumblebees

Bombus/Psithyrus rupestris, Red-tailed cuckoo bumblebee

She takes over the nests of Bombus lapidarius. Has darker wings than Lapidarius. Body lengths, female (above left) 22 mm, male (above right) 16 mm. Forewing lengths 19 mm female and 14 mm male. This is a very large bee with smoky dark wings. Females fly from May or June, and males and new females from July. The males form small mating swarms or leks to attract females on hillsides. Favourite flowers include dandelions, comfrey, oil-seed rape, thistles teasel, ragwort, brambles and scabious. It is found from the Midlands southwards, though it is rarer in Wales and the west. It has not been recorded from Scotland and is rare in Ireland.

Bombus/Psithyrus sylvestris, (Forest cuckoo bumblebee)

Common and takes over the nests of Bombus pratorum and jonellus. Body lengths, female (above left) 15 mm, male (above right) 14 mm. Forewing lengths, female 15 mm, male 13 mm. Male hair colour is very variable. Females can be seen as early as late March in the south, and males in April, therefore there would appear to be two generations in the south. In the north they are not normally seen until May. As their Latin name suggests they are found in wooded areas. Favourite flowers include, dandelion, nettles, bilberry, thistles, bramble and scabious. They are fairly common throughout Britain, but rare in the Channel Islands. Males tend to patrol mating circuits within 1 m off the ground. There are also reports of them lekking groups to attract females.

Bombus/Psithyrus bohemicus, Gypsy cuckoo bumblebee

Common and takes over the nests of Bombus lucorum. This is the commonest cuckoo in the Scottish highlands. Found in heathland, high meadows, and birch and pine woodland. Body lengths, female (above left) 19 mm, male (above right) 16 mm. Forewing lengths 16 mm female, 14 mm male. Females fly from April in the south and May in the north. Males and new females can be seen as early as June. Favourite flowers include dandelion, bilberry, thistles, brambles, heather, and scabious.

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 (above left) 21 mm, male (above right) 16 mm. Forewing lengths, female 18 mm, male 14 mm. Females fly from late March, and males from late May. Preferred flowers include sallows, blackthorn, cherry, dandelion, ivy, dead nettle, thistle, teasel, bramble and lavender.

*It has recently been confirmed that this bumblebee was found in southern Scotland in the summer of 2009.

Bombus/Psithyrus barbutellus, Barbut's cuckoo bumblebee

Common and takes over the nests of Bombus hortorum and B. ruderatus. It is found mainly in England and sometimes in Wales, it is rare in Scotland and Ireland. Body lengths, female (above left) 18 mm, male (above right) 15 mm. Forewing lengths female 16 mm, male 13 mm.

Females are seen from April, males are most numerous during June and July, new females emerge from September.

Preferred flowers include, dead nettles, hawthorn, thistles, clovers, knapweed and Buddleia.

Bombus/Psithyrus campestris (Field cuckoo bumblebee)

Common and takes over the nests of Bombus pascuorum. Body lengths, female (above) 18 mm, male, light and dark forms below, 15 mm. Forewing lengths 15 mm female, 13 mm male. Females fly from April and males from June. There may be two generations of this species per year in the south. Favourite flowers include, ivy, dandelion, clovers, hawthorn, thistles, knapweeds, brambles and scabious. It is fairly common in England and Wales, rare in Scotland and Ireland.

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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