As the winter chill fades and days get brighter, insects emerge from their shelters to enjoy the floral offerings of early spring. Since many insects depend on external sources of heat to warm themselves, they will only emerge when temperatures are high enough. Once the right temperatures are reached, we will notice our green spaces filling with beetles, butterflies and bee-flies.
So what are bee-flies?
Bee-flies are fascinating insects that have mastered the art of mimicry. These agile, fluffy, flying creatures look similar to bees, but they are in fact flies. They have only one pair of wings, whereas bees have two, and their most unmistakable feature is a long, straight, straw-like tongue, known as a proboscis.
One of the first bee-fly species seen in spring is the dark-edged bee-fly (Bombylius major), common across Britain and a frequent garden visitor. It has yellowy-brown hair, a long tongue, and darkened wing edges that extend halfway across each wing.
Bee-fly behaviours
One peculiar behaviour displayed by the bee-fly is its slow-moving hover where it lightly touches the ground. It keeps its legs slightly grounded, while slowly and gently brushing the surface with its abdomen – if you look closely, you can see the abdomen creates movements in the sandy surface. This is because the bee-fly is scooping up sand and mud to coat its eggs for camouflage.
This camouflage is important, as bee-flies will lay their eggs in unsuspecting solitary bee burrows, hovering over the burrow entrances before catapulting their eggs inside. As the eggs hatch, the bee-fly larvae spend their time maturing in the nest, eating up the pollen stores that the solitary bees have left for their own young. Although this sounds like bad news for the bees, a healthy population of bee-flies means that you have a good population of bees.
Garden benefits
After a long winter, bee-flies are hungry and looking for nectar, which they extract by various means. Firstly, they may hover alongside the flower, using their long tongue to reach the nectar. They may also land on petals, allowing them to reach nectar at the bottom of the flower. Finally, they may break through the bottom of the flower as a shortcut, an act known as ‘nectar robbing’.
While they gorge on nectar, they also collect pollen on their tongue, legs, and body and transfer it between flowers, pollinating them as they search for nectar. The dark-edged bee-fly is not a picky eater and will visit many spring flowers. But if you want to see one, a patch of primroses is a great place to start or sunny areas of bare ground where they bask to warm up.
Frequently asked questions
- Can bee-flies bite or sting?
- No. Their long tongue may look fierce, but it is just used for feeding on nectar.
- How many species of bee-fly are there in Britain?
- There are approximately 10 different species, which vary in colour, ‘fluffiness’ and wing patterns. The most commonly encountered species is the Dark-edged Bee-fly.
- Where should I record my sightings?
- iRecord is a great universal recording platform that feeds data to other organisations such as the National Biodiversity Network (NBN). This is important as the data can be used and accessible to students, research organisations and conservation projects. Plus, the Dipterists Forum have an ongoing initiative called ‘Bee-fly Watch’, with a form that can be completed to record your sightings without having the need to create your own iRecord account. You can find the form and more information on their website.
Learn more about the fascinating world of invertebrates with our biodiversity courses.
A version of this blog was originally published as an article in Amateur Gardening magazine in 2024.