Another cuckoo
30th July 2009, ThursdayWalking along the sea wall at Pett I caught site of a jet black bumblebee foraging on knapweed. It was either something good, or very good so soon it was inside my butterfly net so I could examine it more closely. Totally black bumblebees in Britain are likely to be one of two species. The really exciting one is a melanic form of the large garden bumblebee Bombus ruderatus. This is one of several species that are currently extinct on Romney Marsh, and it is listed on the UK Biodiversity Action Plan. This bee became so rare in Britain that some bumblebee experts even doubted it existed, believing it to be a form of the very similar small garden bumblebee Bombus hortorum. It was then discovered in the Ouse Washes, and with the advent of the Entry Level Scheme, where farmers are paid to plant clover plots as a source of pollen and nectar, it is currently on the increase in Britain, and DNA studies have confirmed it to be a genuinely separate species.
Field Cuckoo Bumblebee
It has not yet found it’s way back to Romney Marsh and Rye Bay, however. B. ruderatus has a very long narrow face, whereas this bee had a short more rounded face, making it the other species that has a melanic form in Britain, the field cuckoo bumblebee Bombus (formerly Psithyrus) campestris. This cuckoo bee lives inside the nests of the common carder bee Bombus pascuorum, and possibly other carder bee species too, where it eats the eggs of its host, and removes their larvae before making eggs cells of its own from destroyed host cells.
This is the first time I have seen this bee in the RX area, although there are historical records along our coast. As with other cuckoo bees it experiences fluctuations in its abundance.
Meanwhile, on Pett sea wall I was actually looking for the brown banded and moss carder bees, as there was quite a bit of red clover, tufted vetch and bird’s-foot trefoil. Sadly neither species was seen.
(Thanks to Chris Bentley for taking the photograph)