The Bee-fly
SPECIES OF THE MONTH
April 2022
Bee-flies are one of the first insects on the wing in spring. With their little, fuzzy bodies and long proboscis. they are both cute and fearsome-looking insects.
Fast facts
Size: 15–18mm long with a wingspan of 25mm
Distribution: Throughout the U.K. More common in southern England
Seen: late March to June
Habitat: Gardens, parks and woodland rides
Food: Adults – Nectar; Larvae – pollen, honey and bee grubs
Bee or Fly?
The bee-fly’s name describes it perfectly. This fuzzy little insect spotted buzzing around in the spring and early summer is indeed a fly that just happens to look like a bee.
A quick way to tell the difference between a bee-fly and a bee is to count its wings when it settles somewhere. Bee-flies, as true flies, have just one pair of wings held away from their body, while bees have two pairs of wings held close to their body.
Pollination
Bee-flies feed on flowers like primroses and violets in gardens, parks and woodlands. Their long proboscis is ideal for reaching the nectar at the base of flowers and, if necessary, they can extend their mouthparts to reach the nectar of deeper flowers. When feeding they usually hover in front of the flower and hold on to it with their front feet for stability. Their proboscis becomes covered in pollen that they then transport to the next flower they feed on.
However, some bee-flies have discovered the same nectar-robbing technique that some bees use, where they stab the base of the flower to get to the nectar. Flowers aren’t pollinated when they do this so it earns them the name ‘flower thieves’.
Bee-flies exhibit a unique flight behaviour where they rotate very quickly around the vertical axis, which is known as"yawing"
Despite their fearsome-looking proboscis they don't bite or sting, and they don't spread diseases.
Eggs & Larvae
Bee-fly larvae are nest parasites of ground-nesting and solitary bees, and feed on the grubs. Mimicing a bee allows them to get closer to solitary bee and wasp nests where they will deposit their eggs.
Females scoop up sand and gravel to coat their eggs to protect and camouflage them while also giving them extra weight. She then flies over to the solitary bee’s nest and flicks out the eggs, ‘bowling’ them towards the nest entrance.
Bee-fly larvae have false legs and use them to move further into the nest, where they eat any stored honey or pollen they find as well as the grub itself.
Egg-laying in slow motion
Created by:
Suffolk Biodiversity Information Service
Image credits, from top to bottom:
Martin Cooper, Paul Kitchener (x5), all from Flickr.com