CONSERVATION
&
MANAGEMENT
The flies (Diptera) of Epping Forest
JOHN ISMAY
Hope Entomological Collections, Oxford University Museum of Natural History,
Parks Road, Oxford, 0X1 6PW
Introduction
The true flies (Diptera) of Epping Forest have been the subject of study for many years. Brunetti
(1890) listed 50 species from the Forest and more recently Hanson (1992) listed 890 species. The
Corporation of London commissioned a survey of flies, as part of the Forest Insect Survey, in 1998.
In March 2000 the survey had recorded 1308 species, including those on Hanson's list, and in
February 2001 the list had 1586 species. There are currently 6702 species of flies recorded from the
British Isles (Chandler 2000), so 24% of the British species are known from Epping Forest.
One reason for conducting this survey was simply to find out what was in the Forest. The list can
also be compared to those from other old forests, such as Windsor Forest or the New Forest, to
assess relative importance. More importantly it will act as a baseline for future monitoring, to see
what effect climate change and management practices have on the insects in the Forest.
Methods
The Forest Insect Survey was conducted using several methods of collecting. A team of recorders
visited the Forest for several days in 1998, 1999 and 2000 and collected using hand netting and
searching. Concurrently two Malaise traps (Plate 8) were run at two locations for the entire period.
The coverage of different groups was uneven, because no one individual can cover all families of
Diptera. Some families such as Syrphidae (hoverflies) and Sciomyzidae (snail-killing flies) are well
known and there is accessible identification literature, while others are poorly known in Britain or
can only be identified by a specialist. The material collected was therefore distributed to specialists
for identification.
In the major groups of insects there arc Conservation Reviews which list the species which fall into
Notable or Red Data Book categories. Because of the problems noted above, only about 4000 of the
6702 species of flies on the British List have been considered for conservation status (Falk 1991)
and these species were selectively targettcd for identification. For example, 137 Syrphidae out of
267 British species (52%) were recorded but only 18 Cecidomyiidae out of 620 British species
(3%). Thus even the 1586 species recorded are an underestimate of the true richness of the Forest.
Essex Naturalist (New Series) 18 (2001)
105