If you see a violet carpenter bee, Xylocopa violacea, in Britain, it seems too exotic for our shores, and too big. It is up to 3cm long, the size of our largest bumble bee, and it looks even larger when flying with an impressive buzz.
In late August, the adults emerge from a dead tree trunk or other old wood where they have spent the larval stage. After mating in late April or May, female bees bore holes in rotten wood and lay eggs in separate chambers, each one sealed in with a store of pollen so the emerging larvae can have a good start in life.
Climate change has brought this southern European species to our shores. It was first spotted breeding here in 2007 in Leicestershire, but it is still extremely rare, almost certainly because of lack of suitable breeding sites rather than the climate.
The bees need rotting wood, soft enough to create nesting holes, hence the name carpenter bees. They have been accused of destroying wooden buildings but they only start colonising when the wood is already rotten so the structure was in danger before they arrived. What they are looking for now is old nest holes or other cavities in decaying timber to hibernate until the breeding cycle begins again in the spring.
