Some interesting aculeate Hymenoptera records for 1999-2000
Mason wasps and social wasps (Family Vespidae)
The discovery by David Scott of a nesting aggregation of the Nationally Endangered (RDB1)
Odynerus simillimus at Alresford in North Essex is of international importance and is discussed in
more detail elsewhere in this journal (Harvey & Scott 2001). The Nationally Scarce (Notable B)
Microdynerus exilis was collected by Adrian Knowles at Wimpolc Recreation Ground (TM0124)
on 11 July 1999 and Old Heath Cliff Paddock (TM0123) on 6 July 2000. Ancistrocerus nigricornis
is rare in Essex and has undergone a recent significant decline in Britain (Archer 2000). In Essex it
seems to occur mainly in ancient woodland sites. It was collected by Charles Watson at Hatfield
Forest (TL5419 and TL5420) on a number of occasions in 1999 and 2000 and by the author in
Epping Forest in May 1999. Ancistrocerus scoticus is another species rare in the county, which
David Scott collected at Brightlingsea (TM0518) on 12 August 2000. It is now a predominantly
coastal species that has suffered a severe national decline inland. David Scott collected females of
A. parietinus at Brightlingsea on 22 June 1999 and 11 June 2000 and Adrian Knowles collected a
male and female A. parietum at Fingringhoe Wick (TM0419) on 22 September 2000. Both species
are rare in Essex.
APOIDEA
Digger wasps (Family Sphecidae)
The most exciting sphecid discoveries have been a single female of the Nationally Scarce (Notable
B) Crossocerus binotatus collected by David Scott at Brightlingsea (TM0718) on 20 July 2000 and
a single female Crossocerus capitosus collected by Dan Hackett at Channelsea in the Lee Valley on
15 June 2000, a new county record. The record of C. binotatus appears to be the first in the county
since Harwood recorded it in the Colchester area in 1882 and 1883 (Harwood 1884). Adrian Knowles
collected one male Didineis (Alysson) lunicornis at Levelly Wood (TL7228) on 30 August 2000.
This Nationally Scarce (Notable A) species has been recorded from several Essex localities, mostly
coastal sites with exposed bare clay substrate in sunny situations. At Low Hall Wood (TQ3588) on
15 July 1999, Dan Hackett collected Spilomena troglodytes, a tiny wasp previously recorded in the
county only at Mill Wood Pit in Thurrock. A number of other rare species which are widespread in
the East Thames Corridor, at least until the remaining habitat disappears under concrete or is amenity
landscaped, have been recorded at various localities in south Essex.
The author collected four females of the Nationally Rare (RDB3) Passaloecus clypealis at Northwick,
Canvey (TQ7683) between 23 August and 9 September 1999, and one female at the easternmost silt
lagoon at Wennington Marshes (TQ5279) between Hand 27 June 1999. The silt lagoon revealed a
highly significant and important invertebrate fauna but the habitat of both this and the adjacent
lagoon has now been destroyed, at least for a good many years, by their unexpected re-use to take
dredgings from the Thames. The Nationally Scarce (Notable B) Nysson dimidiatus, a cleptoparasite
of Gorytes tumidus, a scarce species in Essex, was collected by the author at Temple Mills (TQ3686
and TQ3786) between 13 and 27 July 1999, at Barking (TQ4682) between 27 July and 14 August
2000 and at Wennington (the silt lagoon at TQ5279 and the riverside at TQ5278 and TQ5379)
between 14 and 27 June 1999. The author also collected the Nationally Scarce (Notable A) Mimumesa
(Psen) unicolor at the Wennington silt lagoon site between 14 and 27 June 1999, Barking between
27 July and 14 August 2000 and Northwick, Canvey between 23 August and 9 September 1999.
The RDBK (Insufficiently Known) Stigmus pendulus was first recorded in Essex at Wanstead and
Leyton Flats by Mark Hanson (Hanson 1992; Falk 1991), but the wasp has been spreading in southern
England and is now widespread in some parts of Essex. Records are concentrated in the Waltham
Forest and Epping Forest area where it has been recently collected by Dan Hackett and the author,
and around Colchester where it has been collected by Adrian Knowles, but there are also records for
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Essex Naturalist (New Series) 18 (2001)