Dark-edged Bee-fly

• It is a kleptoparasite: in mid-flight it flicks its eggs towards the entrances of solitary bee nests, and the larvae that hatch devour the provisions and the bee's own larva.
• Its proboscis is rigid and cannot be folded away, so it carries it out in front like a lance, although it is completely harmless and does not sting.
• Its hovering flight, with the legs dangling and the wings almost invisible, is one of the most recognisable sights of early spring.
• It looks like a furry bumblebee but is a fly, and its long rigid proboscis, always held stretched out in front, gives it away: it does not sting, it only sips nectar.
• It hovers in front of the flower, legs dangling, and drinks without ever quite landing.
• Its larva is a parasite of the nests of solitary bees, and the female has a remarkable method for reaching them: she hovers over the nest entrance and flicks her eggs in mid-flight, like someone throwing darts, without landing.
• To do so she first gathers sand or dust in a chamber of her abdomen and coats the eggs with it, giving them weight so that the throw is accurate and the wind does not carry them off.
• The newly hatched larva enters the cell and devours the bee larva and its provisions.
• It is one of the first insects to be seen flying in spring, and an important pollinator of early flowers.

Skeleton type

Invertebrate - chitin exoskeleton (insect)

Habitat and environment

Forest edges, gardens and sunny banks with solitary bee nests

Sexual maturity

It shows hypermetamorphosis: the different larval instars have completely different forms, first a mobile larva that searches for the host and then a sedentary parasitic form

Gestation / incubation

The larva hatches inside the burrow, crawls to an open cell of the host and stays inactive until the bee larva is about to pupate; it then turns into an ectoparasite, attaches to it and sucks out its body fluids. The pupa can overwinter

Litter / clutch size

The female hovers over the entrance to the nest of a solitary mining bee, mainly of the genus Andrena, and flicks the eggs inside with a snap of the abdomen. She prefers groups of nests on a bank or slope, where the angle of fire is better

Sources consulted: Wikipedia (es): Bombylius major · Ficha de especie de Bombylius major (Boesi, Polidori & Andrietti) · UWM Field Station · NPS/iNaturalist, ficha Greater Bee Fly (Oldroyd 1964 · Stubbs & Drake 2001) · NPS/iNaturalist, ficha Greater Bee Fly (Stubbs & Drake 2001 · Paxton & Pohl 1999) · Recopilacion sobre Bombylius major · NPS/iNaturalist, ficha Greater Bee Fly · guias de la familia Bombyliidae · Ficha de especie de Bombylius major

Best time: Appears in late March, is abundant until late May and is still seen into June; it flies by day over the first flowers of the year and roosts in the treetops