Bee Flies (Bombylius major) were in abundance last weekend when it was bright and sunny out. Usually I might see one but on that day I saw several. I was looking for bees and I think so were the flies. I always thought their only relationship to bees was that they had the same fuzzy butts that some bees have but their story is a little more complicated than that.
They prey on bees! Or at least their larvae prey on bee larva. I guess that is like saying, “my kids, eat your kids.” Gruesome! Anyway, they lay their eggs near the entrance to the bee’s nest, mostly solitary bees that nest in the ground. Some species sort of flick their eggs into the holes. There are over 5,000 bee flies worldwide so I am generalizing here. The parasitoid larvae enter the hole and begin feeding on the food storage for the host bee larvae and eventually eats the host bee larvae as well. Now get this, later when the bee fly larvae is more mature it turns into a grub-like larvae before it become a bee fly. This is called hyper-metamorphosis. Frankly I’m glad this all goes on underground.
Above ground in the sunshine the bee flies are a lot of fun to watch. The proboscis is long and points forward and they feed on many of the same flowers that bees do. However they hover over the flower like a Clearwing moth or Hummingbird, I guess that is why they need the long proboscis. This seems to be a good strategy to keep clear of predators like crab spiders lurking between the flower petals.
Isn't it cute!