spread in Britain though there are a number of rare or uncommon species: Lonchoptera
tristis, Macrocera maculata, Rhamphomyia gibba, Systenus pallipes, Eustalomyia
hilaris, Phaonia trigonalis, Steganina coleoptrata and Leia piffardi.
Most species recorded are typical of woodland, among them many of the Tipulidae
and Mycetophilidae and the robber-flies Neoitamus cyanurus, Dioctria baumhaueri and
Dioctria linearis. Some of the hover-flies recorded are also typically woodland species,
among them Ferdinandea cuprea, a species whose larvae feed in sap-runs, while two
species which have been reared from decaying beech wood are Xylota sylvarum and
Xylotamima nemorum. The rare Systenus pallipes has been taken on very few occasions
in Britain and in common with other members of the genus is more usually reared from
rot-holes or sap-runs (elm and beech are recorded) and many of the records of this genus
come from long established woodlands.
The burnt and disturbed area with its abundance of grasses, rushes and sedges has
provided habitat for a number of grassland species among them members of the
Chloropidae, The abundant soft rush (Juncus effusus) growing on this area no doubt
accounts for the presence in some numbers of Loxocera albiseta and Cerodontha luc-
tuosa, two species as larvae recorded mining the stems of this plant. Likewise, one or
other of the sedges (Carex spp.) probably 'hosts' the larvae of Cordilura albipes. The fly
Lauxania cylindricornis is a species typically found in acid grassland (64).
A number of the Diptera recorded are typically found in wet or marshy areas. These
include Anasimyia lineata, Epicypta limnophila, Platycheirus fulviventris and
Hydromya dorsalis, the latter is also of interest since it is the sole representative of the
Sciomyzidae taken on the burnt and disturbed area, this no doubt reflects the poor
mollusc fauna of this area (Sciomyzid larvae predate molluscs) (64).
It takes many years of recording to even approach finality in the list of Diptera of a
given area and finality in such a list is impossible to achieve. Parmenter (48-50) after 25
years of recording on the 380-acre Bookham Common in Surrey listed 1,175 species of
Diptera but over 700 of these records were made in the first 3+ years of the survey. It is
difficult to be sure of the absence of an insect from an area particularly as I have
recorded largely over just a single year (1979) but a number of Diptera have been
conspicuous by their absence. The lack of aquatic habitats no doubt accounts for the
absence of families such as the Dixidae and Chaoboridae (though the latter at least
could occur in the vicinity of the adjacent Knighton Pond), similarly the lack of any
large mammals would account for the absence of families such as the Tabanidae. I
neither captured nor saw any of the common 'cleg' (Haematopota pluvialis) though I
took this species elsewhere in Epping Forest in 1979. Other families, the representatives
of which are rarely met with, such as the Acroceridae, the Xylomyidae and some of the
uncommon acalypterate families are expected absences. I was, however, surprised not to
record any Bombyliidae; I did much work in the early spring in Lords Bushes in 1979
and though noting the bee-fly Bombylius major not uncommonly about many grassy
rides in Epping Forest I saw no specimens in Lords Bushes.
The majority of Diptera were collected, unless otherwise stated, by using a net
'sweeping' the burnt and disturbed area. The larger insects were tubed individually and
the smaller insects collected from the net using a pooter.
Nomenclature follows Kloet, G. S. & Hincks, W. D. (41) with the exception of
Epicypta limnophila nom.nov.
DIPTERA hiemalis quadrifaria
saltator Tipula lunata
NEMATOCERA marmorata
TIPULIDAE maxima
TRICHOCERIDAE obsoleta
Dictenidia bimaculata oleracea
Trichocera annulata Nephrotoma flavipalpis paludosa
51