The Pine Hoverfly

My experience attempting to boost populations of the Pine hoverfly, Blera fallax, is what inspired the Hoverfly Lagoons project. The Pine hoverfly develops in rot holes in Caledonian pine stumps and roots, and shares its habitat with other species of hoverfly. While the larvae develops very well in captivity, the females are very particular and during my time on the project, wouldn’t lay eggs in the ‘Lagoons’ I created in the field. However, they readily oviposit eggs in holes drilled into pine stumps.

The Pine hoverfly is currently struggling to survive in Scotland. After the Malloch Society’s work under the SNH Species Action Framework, efforts continue to monitor the population, create breeding and foraging habitat, and captive breed it. This page is designed to inform and aid surveyors in identifying the different stages of this species.

Male Pine hoverfly
Female Pine hoverfly (with paint mark on wing, for identification in captivity)
The head end of a Pine hoverfly larva

The main larval stage character that identifies the pine hoverfly is the moustache-like anterior spicules, seen above.

The pupae can be identified by the size (compared to larger species), breathing tube (presence), and colour. The pupal case tends to be a lighter colour than other species, and transparent, allowing you to see the adult development inside.

Blera fallax pupae (showing development through pupal case, indicated by orange head-end)

Two Blera fallax pupae on pine stump, one early stages of pupation (white) the other later stages of development showing colours of the adult fly through pupal case

Demonstrating nicely the transparent pupal case allowing observation of the stage of development, here you can see the black body and orange abdominal tip of the adult
Empty Blera fallax pupal case, light/white in colour, head end exit hole

OTHER SPECIES that surveyors may come across

Eristalis pupa (much darker pupal case, with a tell-tale tubular shape and long anterior spiracles)
Callicera rufa (shortened breathing tube, also larger)
Myathropa florea (larger and darker with striped pattern, pending a better image!)
Sphegina clunipes (much smaller species)
Helophilus sp. (unlikely to come across in pine stumps or tree holes, similar shape and size)