Meet the Bee-flies
Bee-flies are remarkable insects known for their cute and fluffy bee-like appearance and fascinating, and rather gruesome, life-cycles. According to the Natural History Museum there are ten bee-fly species in the UK but most are rare. If you see one it’s most likely to be a dark-edged bee-fly.
What they need
- Adult bee-flies rely primarily on nectar, using their long tongues to reach the bottom of flowers, and some species steal pollen left next to the baby bees that they are about to parasitise. This means that there needs to be a constant supply of accessible, nectar-rich flowers over the spring, summer and early autumn months that they are active.
- Bee-fly larvae are parasitoids, meaning that they are parasites that will kill their hosts. Several species target solitary bee and wasp nests and you might be lucky enough to see bee-fly females ‘twerking’ their behinds in dusty ground to coat their eggs before flicking them into the nests of their future victims.
- Like all invertebrates and their predators, their survival is increasingly dependent on being free from poison in a clean, pesticide-free environment.
What you can do to help
- Create bee-fly-friendly habitats by planting a variety of flowers that bloom throughout the year, providing nectar and pollen for adult bee-flies and their larvae. Bee-flies tend to avoid bright yellow and pink flowers in favour of white, blue, purple and violet ones so add these to your planting palette.
- Provide for the solitary bees (see ‘Bumblebees and solitary bees’ spotlight species group) that bee-fly larvae depend on. Theirs may be a gruesome lifecycle, and certainly no fun for the baby bees, but they live in balance with bees and parasitism is extremely common amongst invertebrates.
- Incorporate features like log piles, wild patches, rockeries, green walls, leaf piles and other undisturbed areas into outdoor spaces to provide shelter and sunbathing sites for bee-flies.
- Avoid pesticides as these chemicals can harm bee-flies and the animals that depend on them for food.
Fascinating facts
- Bee-flies mimic the appearance of bees and wasps to deter predators, even though they cannot sting. Those long sticky-out bits you might see at either end are entirely harmless tongues and ovipositors (egg-depositors).
- Bee-flies are true flies, but do look a lot like bees! You can tell the difference by how many wings they have and how they hold them when at rest: flies have one pair of wings held open whereas bees have two pairs of wings that fold neatly back. Like bees, though, they are valuable pollinators.
- Bee-fly larvae undergo an extremely rare form of secondary metamorphosis called ‘hypermetamorphosis’. After hatching, they crawl into their host’s burrow, steal the pollen left there by the baby bee’s mum, then metamorphose again into a larger larva that parasitises the baby bee.
