Many of us will be spotting Bee-flies in the garden and in the Forest at the moment. The commonest of the four native species is Bombylus major, the Dark-edged or Large Bee-fly, with dark patches on the edge of each wing. It is worth looking closely at the wings as the less common Spotted Bee-fly, B.discolor, is also found in the Forest. It is very slightly smaller and has spots on its wings.
These odd-looking furry flies are parasites on Andrena mining bees. They adults deposit their eggs by flicking their abdomen, to propel the eggs towards the mouth of the bee’s nest. According to research done in both Russia and Japan they are not particularly accurate! They also have another strategy where they simply lay their eggs on plants visited by the bees which stick to them and are then transferred to the nest.
Bombylius flies have a long, rigid proboscis. which is used for feeding on nectar and pollen. The females eat more pollen than the males as, probably, they need more protein for egg production. They do not pollinate the flowers, they are just ‘nectar thieves.’ It is said that they prefer blue flowers!
Bombylius flies only superficially resemble bees, unlike some of the Hover flies, so are they mimics or just hairy? It has been proposed that they get a measure of protection from predators by being bee-ish, but also that it allows them to approach the host’s nest without being attacked.