7
TWO RARE INSECTS FOUND IN 1996
A Solitary Wasp
On 19th July I happened to be working at the Priory Museum in Priory Park, Prittlewell,
Southend. This is a half-timbered medieval building standing in the middle of a public
park. It has a balcony from which one can closely inspect the structural timber. These
dark-stained oak timbers are riddled with the past ravages of the Death-watch Beetle
(Xestobium rufovillosum). During a short break from work I noticed several small black
wasps busy flying to and fro from these sunlit beetle holes. They were obviously being
used as nest holes for the wasp. Two specimens were taken and later tentatively
identified as females of Stigmus pendulus [SPHECIDAE]. This was later confirmed by
Steven Falk in November. Stigmus pendulus was unknown in Britain until G.W. Allen
took specimens from Smarden in East Kent in August 1986. Later Mark Hanson took
two females on Wanstead and Leyton Flats in Essex and most recently, records have come
from a malaise trap in the grounds of Buckingham Palace (CW. Plant - pers.comm.).
Three of these localities, Smarden, Priory Park and Buckingham Palace are large mature
gardens. At Smarden a specimen was taken at a wooden post containing old beetle
borings. On the continent where it is also rare, it has also been recorded from holes in the
stems of, for instance, bramble. The cells constructed along each tunnel are provisioned
with aphids.
A Bee-fly
On 4th August I led an Essex Field Club meeting to Cudmore Grove Country Park,
Mersea Island. This was a hot sunny day and several insects of note were recorded.
Whilst walking along the sandy strand edged with Shrubby Seablite and also, incidentally
dotted with people sun bathing and eating lunch, I noticed what I immediately recognised
as a beefly.
It was hovering a few inches above the hot bare sand. Beefly, it certainly turned out to be
with the gorgeous name of Villa modesta (BOMBYL1DAE). This was the first Essex
record of this distinctive fly since F. Smith recorded it from Southend (Verrall) in 1870.
Villa modesta is a nationally uncommon species of coastal dunes but quite widely
distributed around the whole coast as far north as the Firth of Tay. Recent records are
from Cornwall, Isle of Wight, Norfolk, Cumbria, Isle of Man, Mid Glamorgan, Dyfed,
Lothian and Tayside. There are also a few inland records on sandy heathland. Little is
known of the life history of this interesting fly. All British Bombylids are internal
parasites of other insects. The common pattern-winged beefly (Bombylius major) is
familiar in our gardens in early spring and parasitises the larvae of solitary bees. The only
record of Villa modesta being reared from a host is that of Colonel Yerbury rearing an
adult from an unspecified moth pupa found in sand at St. Helens in the Isle of Wight
(around 1900).
Only a few weeks after the visit to Mersea Island, Laurence Watts, a local naturalist,
showed me slides of unidentified flies he photographed on sandy ground at Bawdsey
Point, north of Felixstowe in Suffolk (11th August). Again, these were Villa modesta.
At this locality several males and females were observed. Laurence spent some time
photographing and watching the females apparently egg-laying into hot bare sand. This
behaviour has been noted before, both in this species and other Bombyliids. Egg laying
was obviously assumed at first but it now turns out that the female is actually collecting
sand particles which are stored in a chamber in the abdomen. The grains stick to the
minute eggs, making them heavier. This allows the female to flick its eggs a much
Essex Field Club Newsletter No. 20, February 1997