Clytiomya continua and other important new Diptera: Tachinidae records
PETER HARVEY1 AND DEL SMITH2
' 32 Lodge Lane, Grays, Essex RMl6 2YP email: grays@peterharvey.freeserve.co.uk
212 Tring Gardens, Harold Hill, Romford, Essex RM3 9EP email: de.Ismith444@btinternet, com
The Tachinidae is the second largest family of Diptera, with approximately 8,200 described species
worldwide, and 241 species listed as British by Belshaw (1993), although a number of new species
have subsequently been recorded. All tachinids are parasitoids, their larvae developing within other
arthropods, mainly insects.
The parasitic fly Catharosia pygmaea (Plate 6) was first recorded in Britain in 1996 from grassland
with invading scrub on made-up ground on a disused railway line in Coventry (Falk 1998). A
closely related north American species has been reared from lygaeid bugs, but the specific host/s of
Catharosia pygmaea are unknown. The first author collected one male from silt lagoons at Rainham
(where the habitat has now been lost) in pan traps set between 25th August and 6th September 1998
and several others from the Northwick site at West Canvey where it was first recorded in August
1999 as the fourth British record. The most recent record at this site was a female swept from
Carrot flowers on 28th July 2003. This individual was brought home and photographed (see Plate).
It was interesting that it spent a lot of time on the underside of the flowerhead, rapidly moving from
one part to another much as though searching for potential hosts rather than feeding. The species
almost certainly warrants inclusion in the Red Data Book and will most likely be accorded RDBK
(Insufficiently Known) status when these are reviewed.
Cistogaster globosa (Plate 7) was allocated RDB1 status by Shirt (1987) and Falk (1991). The
most recent review (Falk & Pont in preparation) has provisionally accorded the species RDB2
status. It is known from a few localities in Southern England and is a small though distinctive
species unlikely to be misidentified and probably genuinely rare. The species parasitises heteropteran
bugs, in Europe the shieldbug Aelia (Pentatomidae), mostly A. acuminata (Belshaw 1993), the
only species of the genus found in Britain. The egg is laid on the dorsal surface of the host's
abdomen and leaves the host to pupate in the ground. The fly appears to favour dry grassland where
the host is predominately found (Raper & Smith 2002). Individuals have been seen nectaring on
Carrot in Wales where it was recently recorded for the first time (Howe & Woodman 2001).
The first author collected a single adult off Carrot flowers on 1st August 2002 at an area of
wasteground at Northala Fields in Middlesex, apparently new to Middlesex and a single female
again swept off Carrot flowers on 18th July 2003 at the Former Royal Ordnance Site (Area B:
TQ380989) in the Lee Valley (see paper in section 3 of this journal), new to Essex.
Clytiomya continua (Plate 8) was considered doubtfully British in earlier works and it cannot now
be established whether this had any basis in fact. However its recent occurrence in Britain has been
confirmed by Plant & Smith (1997) who recorded it from Essex at Alsa Sand Pit (TL515263), a
site that may now have been destroyed. The first author found the fly in 2003 on two separate
occasions at the Former Royal Ordnance Site (TQ380989), swept off Hogweed on the 2nd June
2003 and Carrot heads in the same area on 18th July 2003. These represent the second and third
confirmed British records. In Europe this species occurs in dry warm open countryside. It is a
parasitoid of the shieldbug Eurydema. The Brassica Bug Eurydema oleracea (Plate 8 inset) is a
local species that feeds on a wide range of Crucifers. E. oleracea was not recorded during the
Former Royal Ordnance Site survey, but its occurrence would not be unexpected and plenty of
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Essex Naturalist (New Series) 21 (2004)