The Essex Naturalist
33
New records of the Wood ant Formica rufa have come from several sites. John
Dobson recorded workers at Shut Wood on 28th July 1997 and I found a single
worker crossing amenity grassland near woodland at Harts Wood, Brentwood on
8th August 1997. Roger Payne has reported the discovery of Formicoxenus
nitidulus, an ant occurring in the nests of Formica rufa and its allies. I have no
details of this record but it appears to be the first Essex occurrence since the very
old record given for Hockley by Donisthorpe (1927).
Spider wasps (Family Pompilidae)
One male Auplopus carbonarius was taken in August 1996 at Alphamstone Pits
in North Essex. This Nationally Scarce (Notable B) spider wasp stocks its nests
with a variety of free-living spiders, but is a generally scarce and elusive species
(Falk 1991). The species is listed for North Essex in Falk without details and this
appears to be the first record since Harwood's time.
A female Aporus unicolor was collected at carrot flowers on wasteground at St.
Clements Church, West Thurrock on 7th August 1996. This is only the second
recent record of this Nationally Scarce (Notable A) spider wasp in the county,
the first specimen being taken by Colin Plant at the nearby Mill Wood Pit in
July 1995 (Harvey & Plant, 1996). The host spider is the purse web spider
Atypus affinis which is extremely rare in Essex with only three known sites at
Broom Hill Chadwell, Grays Chalk Quarry and Hadleigh Castle and old records
for Epping Forest near High Beach. Although the spider wasp has been taken on
both occasions in disturbed areas, the host spider requires undisturbed habitats
and its location in this area remains unknown.
The Nationally Scarce (Notable A) Priocnemis coriacea has recently been
taken in two sites in North Essex. Two males were collected on 27th April 1996
along the edges of an area of lichen heath at Glemsford Pits (Harvey, 1996a)
and one female was collected at Alphamstone on 25th May 1996. A further
female has subsequently been found in pitfall material from Hall Hill, West
Tilbury, collected in May 1992 but only recently identified.
Spider wasps are often difficult to capture because of their low agitated flight
and ability to rapidly escape between the base of the net and the ground.
Experience with pitfalls and pan traps has shown that they can successfully be
caught by these methods and several other scarce species of Priocnemis have
recently been taken in such traps in the county. Priocnemis spider wasps include
some taxonomically difficult species, but the presence of both male and females
has enabled reliable identification. Two males and four females of the
Nationally Scarce (Notable B) Priocnemis agilis were taken at West Thurrock
PFA lagoons in August and September 1996 and one male and four females
were taken in North Essex at Alphamstone in August 1996. The West Thurrock
PFA lagoons also turned up three males and eleven females of Priocnemis gracilis
(Notable B), apparently new to Essex. The local Priocnemis fennica was common
here and was also recorded in North Essex at Alsa Sand Pit in late June and July
1996 and at Alphamstone in August 1996.