Bee-flies

Field Paintings

One of my favourite insects is now on the wing. The Dark-edged Bee-fly Bombylius major is a beautiful and fascinating creature. Close-up it looks like something out of science fiction, resembling a miniature bee with swept back, chocolate-brown marked wings and an outsized black proboscis.

There was a big emergence of these flies during the incredibly warm week at the end of March. Since that time the cool conditions have slowed their activity but during spells of sunshine they can be found in their favourite spots sipping nectar from the spring flowers.

Males can sometimes be seen hovering in mid-air a few metres above the ground, it is likely that the females find them at these display sites before mating.

Their friendly appearance belies a more sinister side. They are parasitoids of solitary bees. The female can often be seen sitting on bare patches of ground rubbing the tip of her abdomen in the ground. She collects dust in this way and this sticks to her eggs. This weights them and allows her to flick them out whilst hovering over bare patches of ground. These are places where solitary bees are likely to nest.

When the bee-fly larva hatches it crawls around looking for a bee burrow. Once inside the bee-fly larva finds the host bee larva and its food supply of pollen. It then waits beside the bee larva until it has finished feeding. The bee-fly larva then attaches itself to the bee larva and sucks it dry! It then pupates and emerges the following year.

Listen to BBC Radio 4s The Living World – Bee-flies.

John Walters

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