Local entomologist Rosemary Stephens photographed a Glass-winged Dronefly (Eristalis similis) in Tower Hamlets Cemetery Park on 1 May. This is the first record of this nationally rare species in Cemetery Park, and indeed the first in London.
Rosemary commented: “That was a lovely find on Sunday! My son and I had a lovely walk around and did a bit of exploring off the path, which was really interesting. We spotted the hoverfly near the open grass patch near the railway side. I had no idea it was Eristalis similis when I spotted it, until I looked at the photo when I got home and couldn’t place it in the right species.” The identification was confirmed from the photograph (see above) by national hoverfly experts Roger Morris and Stephen Falk.
The Glass-winged Dronefly was first recognised in Britain by Stephen Falk in March 1990, at a site near Coventry during a very hot and early spring, and has been recorded a few times since (plus an older 1942 record from Norwich recently came to light). It is a common species of southern Europe, which has been spreading north in recent decades, and is prone to eruptive movements. Stephen Falk proved it is now a British breeding species by finding a freshly emerged female in coastal grazing marsh in Sussex in 2011.
This is a large hoverfly, similar in size to the Common Dronefly (E. tenax) or a Honey Bee. In continental Europe it is associated with mature to over-mature deciduous forest and Mediterranean evergreen forests, and British records have mostly come from woodlands. Adult males hover at 2-4m over woodland tracks, and both sexes can be found sitting on sunny trunks or visiting flowers.
The larvae of the Glass-winged Dronefly remain undescribed, but those of other members of this genus are of the aquatic type known as “rat-tailed maggots”. Water-filled ditches and drains are probably the main breeding sites for the species.