7
The hoverfly Psilota anthracina in Essex
On the 24th May 1993 I collected a specimen of the rare hoverfly Psilota anthracina at
the western edge of Mill Wood in Thorndon Park south Country Park. The edge of the
wood here has a lot of Hawthorn and Blackthorn facing an arable field (growing a Rape
crop) as well as a number of very old large oaks. The hoverfly has been taken in Essex
twice before, at Dagnam Park in 1981 by Del Smith and at South Weald Park on the 27th
May 1985 by Peter Kirby.
Psilota has a national status of Vulnerable (RDB2) and is known from a small number of
sites in southern England. The New Forest and Windsor are its stronghold. Apparently
the biology of the fly is unknown although the distribution suggests a possible link with
dead wood. Adults have been recorded from April to June and characteristically visit the
blossoms of hawthorn and sloe ("A review of the scarce and threatened flies of Great
Britain Part 1", Falk 1991). If my memory serves me correctly I took this specimen
flying around one of the large oak trunks between stretches of hawthorn and sloe.
Three weeks earlier I had taken two male Criorhina floccosa together with one male and
two female Criorhina asilica (nationally Notable) all from the same edge of the wood.
These hoverfly species are known to have a requirement for dead wood and it would
seem that this woodland has an important dead wood fauna. I am grateful to Colin W.
Plant for confirming the identity of the specimens.
Peter Harvey
WHATS ON: ESSEX FIELD CLUB
JANUARY
Sunday 30th General Meeting No. 1382. Hanningfield Reservoir for Wintering Birds.
Meet 10.30am on causeway. TQ 723971. Leader John Bath. Phone: 0277
651890.
FEBRUARY
Saturday 19th General Meeting No. 1383. "Travels in the Rockies". Talk by Brian
Eastcott at 3.00pm. Red Cross Hall, London Road, Chelmsford. (Car
Park entrance in Writtle Road). Tea and biscuits provided.
Saturday 12th Annual General Meeting No. 114. Red Cross Hall, London Road,
Chelmsford. (Car Park entrance in Writtle Road) at 3.00pm followed by
Presidential Address "The Wild Service Tree". Tea and biscuits provided.
Sunday 13th
Bird Group. Cudmore Grove Country Park. Meet 11.00am at Visitor
Centre Car Park. TM 065147. Leader John Bath. Phone: 0277 651890.