Heath bee-fly (Bombylius minor)
|Size||Body length: 7 - 8.5 mm|
Classified as Vulnerable in the UK.
Bee-flies are named for their resemblance to true bees. However, they belong to the order Diptera (flies), which only possess two wings, whereas bees have four wings. The second pair is not easy to see in the field, and the best way to identify bee-flies is from their much shorter antennae. Bee-flies are divided into two groups, those with long tongues and those with short tongues. The heath bee-fly belongs to the group with long tongues and this provides another means of identifying them from bees. The heath bee-fly has a brown furry body, a relatively short abdomen, and proportionately long wings, which are held outstretched when the insect is at rest.
The heath bee-fly is found throughout temperate and southern Europe, but in the UK it is restricted to the Isle of Man and a few heath sites in east Dorset. Historically, its range was the south of England around the New Forest, and there are single records from Devon and Wales.
This is a species of open heathland, especially areas where there are exposed sandy banks and bluffs along the edges of paths.
All bee-flies are parasites of other insects, and the heath bee-fly larva is a parasite of solitary bees of the genus Colletes where these are using vertical banks as nesting sites. Female bee-flies have a rather hit-and-miss procedure for getting their larvae into their host-bee's own larval cell. They collect fine dust in a 'basket' under their abdomens, and lay their eggs whilst hovering. They coat the eggs in dust and flick them at small holes along sandy banks. The coating of dust helps to camouflage the emerging grub, which then finds its way into the bee's burrow, but it is not known whether they feed on the bee grub or its food store. The adults are nectar-feeders and can be found on the flowers of bell heather, but they seem to prefer much scarcer plants associated with bare ground. The heath bee-fly is on the wing from mid-July to August.
The loss of much of Britain's heathland has resulted in the disappearance of many species that depend on this habitat. Heath is a habitat that requires careful management or it can become covered with scrub and rank vegetation. This management has often been absent from many otherwise suitable sites.
The heath bee-fly is listed in the UK Biodiversity Action Plan, and included in English Nature's Species Recovery Programme. parasites can be very vulnerable to changes in the population size of their host-species. In this species, a lack of suitable heathland management can reduce the opportunities for host larval cells to be dug into bare earth. This situation also reduces the chances of the early-colonising plants (the food-source for the adult insects) being able to gain a foothold.
There is still relatively little known about this insect's biology, and more field work is essential before the true status of the heath bee-fly is known. Only then will it be possible to implement plans to conserve it, together with many of the other species that depend on this apparently fragile heathland habitat.
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- Abdomen: in arthropods (crustaceans, insects and arachnids) the abdomen is the hind region of the body, which is usually segmented to a degree. In crustacea (e.g. crabs) the limbs attach to the abdomen; in insects the limbs are attached to the thorax (the part of the body nearest to the head) and not the abdomen. In vertebrates the abdomen is the part of the body that contains the internal organs (except the heart and lungs).
- Antennae: pair of sensory structures on the head of invertebrates.
- Larva: stage in an animal's lifecycle after it hatches from the egg. Larvae are typically very different in appearance to adults; they are able to feed and move around but usually are unable to reproduce.
- Parasites: an organism that derives its food from, and lives in or on, another living organism at the host's expense.