The Cuckoo (Bees) have arrived!

With the bee season in full swing now and the continuing hot weather, not only are there tons of bees around but also loads of other species that depend on the bees to survive!

I found my first Cuckoo Bumblebee at NQ Growboxes in early June. They’ve almost certainly been there before but it’s only as I grow a bit more confident in my identification skills that I’ve been able to pick them apart from other bumblebees.

Cuckoo Bumblebees pretty much work as the name suggests. The female sneaks into an established Bumblebee nest where she seeks out and kills the queen. She then lays her own eggs in the nest which are brought up by the existing host species workers. These eggs develop into new Cuckoo Queens and males only, no workers are produced. Cuckoo Bumblebees always mimic their host species in appearance, all the better for sneaking into nests undetected. They are generally slightly larger than bumblebees, are less hairy and don’t have pollen baskets. They also have quite round faces and dark wings.

The bee I found at the growboxes was a male Bombus sylvestris, the Forest Cuckoo Bee.

The host species of this bee are Bombus pratorum (Early Bumblebee), Bombus jonellus (Heath Bumblebee) and Bombus monticola (Mountain bumblebee).

A couple of weeks later I spotted a Vestal Cuckoo Bee (Bombus vestalis). Again a male, his species are hosted by Bombus terrestris (Buff Tailed Bumblebee).

He looks quite similar in appearance to Bombus sylvestris, but has a much larger, brighter patch of yellow on his tail which doesn’t have a red tip.

With Leafcutter Bees a common sight at the growboxes at the moment, as are their cuckoo bee Coelixys – the Sharp Tailed Bee.

This female was nice enough to pose on the end of a fence post for me which clearly shows the sharp point to her tail from which she gets her name. This is designed to cut through the leaf cells in which Leafcutter Bees lay their eggs, to allow her to lay her own egg within the cell. When her eggs hatch, they kill the Leafcutter larva, eat the pollen load that has been left for it and develop undisturbed, eventually hatching out at the same time as the Leafcutter Bees the next summer.

While cuckoo bees can be viewed negatively due to the fact that they predate their host species, I’m always interested to see them. They are still vastly outweighed in numbers by their host species, so much so that to see them is quite a novelty. All species of bee (except honeybees, interestingly) have one or several cuckoo species, and they are all playing a part in a healthy, functioning eco-system – they’ll never outnumber their hosts, as this would effectively kill off their own species.

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