|Southern cuckoo bumblebee (Bombus vestalis)|
These other bumblebees are aptly named cuckoo bumblebees and there are six species in the UK. All cuckoo bumblebee species resemble their host bumblebee species in appearance with often the same or a very similar colour pattern as the host species.
The most common species of cuckoo bumblebee in southern and central England is the Southern cuckoo bee (Bombus vestalis). It`s host bumblebee species is the buff-tailed bumblebee (Bombus terrestris). Southern cuckoo bees are often found in gardens, parks and woodlands.
|Host species of Bombus vestalis: Buff-tailed bumblebee (B. terrestris)|
Cuckoo bumblebees often emerge quite late in spring when ordinary bumblebees have already established their colonies. They also have no caste system with queen, worker and males as in ordinary bumblebees but only have females and males. There are important differences between cuckoo bumblebees and ordinary bumblebees, some of them can help you to distinguish between the two types of bumblebee.
2. They have also shortish tongues and are less hairy than ordinary bumblebees
3. The body is much harder than the body of ordinary bumblebees which gives them an advantage in fights when taking over a bumblebee colony
4. The wings are often dusky or dark in colour
|A cuckoo bumblebee, good to see is the harder, less-hairy body|
|Cuckoo bumblebee searching for a bumblebee colony|
It is thought that female cuckoo bumblebees find the host bumblebee colony by smell. They go into the colony and kill or subdue the queen and start laying their eggs. The workers are enslaved with pheromones and/or physical attacks and will rear the young of the cuckoo bumblebee now instead of the young of their queen. After the new generation of cuckoo bumblebees emerge they will leave the nest for mating and the females try to find new colonies to attack.
As cuckoo bumblebees only have to provide for themselves they seem to have a lot of time to just hang around and lazily sipping nectar from flowers now and again. They will never fly industriously from flower to flower as ordinary bumblebee workers will do on a sunny day.
|Several cuckoo bumblebees on Wild marjoram flowers|
|Cuckoo bumblebees often seem to just hang around|
So look out for the “lazy” bumblebees which do not seem to collect any pollen and just seem to hang around, it could be a cuckoo bumblebee.