The Essex Naturalist
31
Interesting Hymenoptera records for 1996 & 1997
P.R. Harvey
32 Lodge Lane, Grays, Essex RM16 2YP.
Hymenoptera records of particular interest for 1996 and up to August 1997 are
described below and update the provisional list published in the previous Essex
Naturalist (Harvey & Plant, 1996). A number of records appear to be new for
the county and other scarce species have been found in new localities.
Records have been made by the author except where stated.
Once again the importance of the East Thames Corridor is demonstrated by
the presence of an extraordinary assemblage of nationally scarce and rare
aculeates and other invertebrates (Harvey 1996b). However the whole area is
threatened by developments and many sites are already lost or will be lost in the
near future.
Recent collecting by Jerry Bowdrey and Adrian Knowles in the Colchester
area, so rich for aculeates in the Harwoods day at the end of the last century,
suggests that this region of Essex may still contain a diverse and important fauna
today. The remnants of heathland and old sand and gravel pits around
Colchester should certainly be investigated, and there is still the possibility that
the remaining grazing marshes could yet reveal the RDB1 wasp Odynerus
simillimus recorded from Colchester and St. Osyth (as O. reniformis) by the
Harwoods (Harwood 1902, Nicholson 1928, Falk 1991). Colin Plant and myself
have found the area south of Sudbury to contain several excellent aculeate sites
and this interesting area should also be more thoroughly investigated.
This account of the more interesting records has been divided into taxonomic
groups for clarity.
Ruby-tailed wasps (Family Chrysididae)
The Nationally Rare (RDB3) Hedychrum niemelai, a parasitoid of the RDB3
sphecid Cerceris quinquefasciata, was found in July and August 1996 at Barking
Levels and West Thurrock PFA lagoons. Both these sites contain areas of
pulverised fly ash (PFA) from nearby power stations. The PFA has developed an
interesting vegetation, especially at West Thurrock where Saltmarsh flora grades
into dry grassland and scrub with plants more typical of calcareous habitats. The
vegetation provides rich foraging and hunting areas for aculeates and the PFA
substrate is apparently used as a nesting substitute for sand.
Two females of the Nationally Vulnerable (RDB2) Chrysis (Chrysogona)
gracillima were collected on 25th July 1996 flying around a dead trunk by the
footpath that runs past Gravelpit Farm Pits near East Tilbury, the second record
for Essex (Harvey 1997). Other specimens, probably of the same species were
seen nearby and the area is another important example of surviving Thames
Terrace gravel habitat.