Worcestershire Record No. 3 November 1997 p. 7
In 1995, entomologist Mike Archer from York University was conducting a survey of Hartlebury Common where he had been studying the bees and wasps for some years. In one of the sand patches on the Lower Terrace he found a collection of holes scattered over an area of several square metres and knew straight away that the bee-wolf had arrived in the county at last. In marketing terms, the solitary wasp known as the bee-wolf Philanthus triangulum is sexy. This is an insect with attitude. It's quite large, bright yellow, attacks honey-bees (no mean feat) and buries their paralysed bodies as you watch! It also has the added chic of being extremely rare in Britain. Or rather, had been. Until the mid-1980s bee-wolves were restricted to a single colony on the Isle of Wight where they dug their burrows in the friable soil of cliff-tops. There were occasional attempts to annex the mainland, but the climate and a lack of suitable immigrants kept an invasion at bay.
At this time the Red Data Book of insects recorded that bee-wolves were threatened and of conservation concern. All of which makes the events of the last ten years even more remarkable. Entomologists studying heathlands in the south of England began to record bee-wolves more regularly. In Hampshire and Surrey they turned up on sandy commons and along the East Anglian coast they tunnelled into dunes and shingle. Eventually they reached Gibraltar Point in Lincolnshire and began to spread westwards towards the Welsh coast and Anglesey. With such phenomenal powers of dispersal, it was inevitable that bee-wolves would arrive on the heaths around Kidderminster .... and they did, with a vengeance.
In August 1997 Harry Green and I found over a hundred burrows in soft sand near the Stourport road at Hartlebury Common . The holes are easy to spot because they are surrounded by a circle of excavated soil as big as a child's hand and if you look more closely , you can sometimes see the corpse of a bee, discarded by the wasp, perhaps when it was disturbed by a dog-walker. As we peered at the holes we became aware of bee-wolves hovering ponderously nearby, each weighed down by a honeybee, slung close to its body, like a Spitfire on a bombing raid. Each wolf made a direct approach to its burrow ....a bee-line!... and vanished into the sand with its prey in a second or two. This was happening continually as we watched and we estimated that up to forty wasps were present. We never saw the capture, which probably happens out among the heather on the common. Bee wolves fly at their prey and sting it below the thorax, paralysing it immediately. Then, having mopped up any excess nectar from the bee's mouth-parts, they head back to the burrow. Just how they find their own hole is well-known thanks to Niko Tinbergen, the Nobel prize-winning naturalist, who studied bee-wolves in Holland in the 1930's. After a reconnoitre from on high the insect comes in low and scans the area around its burrow for landmarks such as pebbles, twigs or pine-cones. It uses these to pinpoint its hole and, as Tinbergen, discovered, can easily be confused if its landmarks are moved. Below ground is a tunnel up to half a metre deep and branching off it are several cells. Each cell is a bee's tomb. The single egg laid on the slumbering bee within will hatch into the wolf-larva which feeds on the bee, before pupating and emerging the following summer. All bee-wolves are wolf-orphans, they never see their parents who die at the end of the season.
As we progressed over Hartlebury Common we found other, smaller colonies, some slap-bang in the middle of paths. They probably benefit to some extent from the bare soil at the path-side, though continual scuffing will disguise their burrows. Later in August we also found a small colony on Burlish Top at Stourport, so it's likely that bee-wolves are more common than we realise in north Worcestershire. Just why they have increased so rapidly isn't too clear. They were always on the north-western edge of their range in Britain and it has been suggested that climatic change has helped them to colonise. Warmer, drier summers mean more active prey and better burrowing conditions, so maybe this is the key to their success. Although they are increasing in range and numbers, bee-keepers have little to fear. Colonies probably account for no more than a few hundred bees each season, a small price to pay for sharing our county with the charismatic bee-wolf.
|Richards, OW (1980) Scolioidae, Vespoidea, and Sphecoidea. Hymenoptera, Acauleata. Handbooks for the Identifications of ||British Insects Vol 6 part 3(b). Royal Entomological Society of London.
||Tinbergen, N (1958) Curious Naturalists. Country Life: London.
||Tinbergen, N (1972) The animal and its world. Explorations of an Ethologist. 1932-72. Vol 1: Field Studies. Allen & Unwin: London [contains translations of the original research on Philanthus].
||Yeo PF & Corbet S (1983) Solitary Wasps. Naturalists Handbooks No 3. Cambridge University Press.