Leopoldius brevirostris (Germar) (Diptera: Conopidae), new to Essex
NEIL HARVEY
22 West Street, Rowhedge, Essex, COS 7HN
Whilst searching for Greater Dodder Cuscuta europaea plants on the southern bank of the River
Stour at Langham Water Treatment Works on 19 July 2002, I managed to sweep a Conopid fly from
nettle leaves at the edge of the riverside path (TM 015344). In a tube it was clearly not one of the
few species I am familiar with and so I took it home in order to key it out. Using Smith (1969) it
quickly became apparent that this was one of the two Leopoldius species as it had the short, fleshy
proboscis characteristic of this genus. The large, black theca and predominantly yellow abdomen
suggested that it was the rarer of the two species, L. brevirostris.
Through the UK Hoverflies news group I was able to get in touch with Dave Clements, the organiser
of the national recording scheme for Conopidae. I sent him an Email that included digital photos,
taken through my binocular microscope, of the key features that had led to my provisional
identification. From these photos he was able to confirm the identification.
Leopoldius brevirostris is a Red Data Book (Vulnerable) species for which Dave Clements has
about 15 widely distributed records nationally. Del Smith, the County Recorder for Diptera, has
confirmed to me that he has no previous Essex records.
As with all Conopidae, the larvae arc solitary internal parasites mainly of the aculeate Hymenoptera,
the eggs laid directly into the hosts in flight. The hosts are unknown for L. brevirostris but it is
likely that species of Vespula arc used, as this is the case with other members of the genus on the
continent. As such it is something of a mystery as to why it is so scarce.
Reference
SMITH, K.G.V. (1969) Diptera: Conopidae. Handbooks for the Identification of British Insects Vol 10 Part
3(a).
50
Essex Naturalist (New Series) 20 (2003)