The Tawny Mining Bee (Andrena fulva) and the Bee Fly (Bombylius major) have a story to tell. The first is a solitary bee while the second is not a bee but a fly impersonating one. Both can be seen on the reserve at St Nicks from April to June. The Bee Fly tries to stay as close to the Tawny Mining Bee as possible. It has a liking for the nectar of primrose-type flowers, and it was among the cowslips at St Nicks in early April 2014 that both species were first seen together.
The Bee Fly looks like one of Britain’s V-bombers of the post-war years, with swept-back wings and a long nose. The ‘nose’ is actually a feeding proboscis, easily seen in the photograph which was taken near the Dragon Stones. The Bee Fly pushes this deep down into a flower while clinging onto the petals with its legs, its wings abuzz to keep it in position, often heard as a high-pitched whine. The proboscis is entirely harmless to humans – it is not a weapon!
The female Tawny Mining Bee – also harmless to humans – is a stunner while the male is smaller, duller and paler. As the picture shows (taken not at St Nicks but on a gooseberry bush in the author’s garden in Haxby) she is a rich foxy-red colour. She stands out brilliantly as she darts rapidly from flower to flower, favouring the nectar of Ribes and Rubus species – currants, gooseberries, raspberries and brambles. Both the bee and the fly are frequently found in our gardens.
After mating, the Tawny Mining Bee excavates a vertical shaft in the earth 8 to 12 inches deep, often in the short grass of lawns and meadows or in field margins. Several brood cells branch off the main shaft while the nest entrance is surrounded by a small volcano of fine earth. She fills the brood cells with nectar and pollen, laying a single egg in each. The eggs hatch into larvae within a few days, feeding on the stored pollen and nectar.
This is the female Bee Fly’s opportunity, and the reason why she likes to keep watch on the activities of the Tawny Mining Bee. She too has mated and her eggs are ready to be laid. She finds the nest shafts of the Tawny Mining Bee, hovers over them and drops her eggs either into the shafts or onto the ground nearby, often flicking her eggs accurately into the target with her legs (slow-motion video is required to see this clearly). The larvae from eggs that miss the target can, after hatching, find their way by instinct into the nearest shaft. Once down inside the bee’s brood cells, the Bee Fly larvae consume the food, gaining strength to change shape and eat the Tawny Mining larvae. They then pupate, emerging the following year as Bee Flies from a Tawny Mining Bee’s nest.
And that is the story these two charismatic-looking insects have to tell. Look out for them on your visits to the reserve in spring and early summer, and be glad that not all Tawny Mining Bee nests are parasitized by Bee Flies.
Text and photographs by Cliff Wilton, a keen and highly knowledgeable member of St Nicks’ team of Wildwatch volunteers. This is a slightly revised version of an article first posted in April 2014, but which later got lost – whoops! At the time of reposting (April 2020) there are reports of many sightings of these two amazing creatures in gardens around York, and beyond.