The flies (Diptera) of Epping Forest
Rot-holes and heart-rot in standing trees have their own fauna and some species prefer drier or
wetter rot-holes or dead wood above ground or deep in rotting roots. Sap-runs, where a tree is
damaged and the sap runs down the bark and ferments, are the home of a special complex of insects
and Epping is rich in these species.
The importance of fungi in the context of damaged or veteran trees was highlighted in the last issue
of this journal (Barges 2000). The flora of fungi known from Epping is rich and is reflected in the
number of insects associated with fungi. Epping has 205 species of fungus gnats out of the 526
British species, a very high proportion.
The Forest is not an isolated habitat; besides the buffer zones the surrounding area is an actual or
potential breeding area for the flies discussed above and gardens in particular can be important
refuges for species associated with dead and diseased trees. Providing they are not a safety concern
such trees should be left to decay naturally and homeowners may be rewarded with the sight of some
of the spectacular insects shown in Plate 9.
A survey such as this one is certain to turn up species new to Britain or to science. One fungus gnat new
to science has been described partly from material collected during the survey and has been named after
the Forest - Mycetophila eppingensis Chandler (Chandler 2001). Peter Chandler has also found several
sciarid gnats of the family Sciaridae which are new to Britain or science. Martin Drake found at least
two species of shore-flies (Ephydridae) which are new to science, though also known from other sites.
Comparisons with other sites
There are many other sites in Britain which are as well collected as Epping Forest, but in most cases
there is no comprehensive list of Diptera for comparison. Windsor Forest and the New Forest would
be good sites to compare with Epping Forest but comparable lists are not yet available. Another
Corporation of London site, Burnham Beeches, Buckinghamshire, has recently been surveyed in
much the same manner and mostly using the same specialists. The total number of species for Burnham
Beeches is 1372 compared to 1586 from Epping. This difference is less significant than it seems
since a much greater collecting effort has been expended at Epping over the years, while some less
known families such as Ceratopogonidae have been scarcely worked at Burnham Beeches. Wicken
Fen, Cambridgeshire is one of the best known sites in Britain and a checklist has recently been
published (Friday & Harley 2000) which lists 1814 species. The species coverage of Wicken is
more even than the other two sites and it is predominantly fenland, while Epping and Burnham
Beeches are particularly old woodland. Table 3 compares the UK, Epping, Burnham Beeches and
Wicken Fen totals for some groups of flies.
Table 3. Numbers of species of some groups of Diptera in Epping and other sites
SITE UK Epping Burnham Wicken
_________________________________________________Beeches_________________
Tipuloidea______________322___________124___________74____________92
Mycetophilidae s.l._______527___________205___________239___________134
Empidoidea_____________675___________190___________186___________231
Syrphidae______________267___________137___________88____________114
Fanniidae_______________60____________26____________34____________20
Muscidae_______________281____________92____________102____________89
Total Diptera 6702 1586 1372 1814
Essex Naturalist (New Series) 17 (2000)
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