Part 2: Nematocera and Aschiza not dealt with by Falk (1991) - JNCC

species must, therefore, be extrapolated from the available information so as to arrive at the best estimate
of the likely national distribution of each species.
3.7. Threats
It is those human activities that result in the loss of sites or that change the nature of habitats that are
most likely to pose the greatest threats to insect populations. Where specific threats might arise they are
mentioned, otherwise the statements attempt to summarise in general terms those activities which are
considered most likely to put populations of these flies at risk. Where known sites have the benefit of
statutory protection, as, for example, in the case of National Nature Reserves (NNRs), this is noted.
3.8. Management and Conservation
Preventative measures and positive action designed to maintain populations are suggested where these
are known or can reasonably be inferred. Inevitably, in many cases this section tends to be generalised,
identifying practices that have been found to favour those aspects of the habitat with which the species
may be associated. Kirby (2001) and Fry & Lonsdale (1991) provide further, more detailed, information
on the management of habitats for the conservation of invertebrates.
3.9. Published sources
Literature references that refer to the previous conservation status of the species in Britain, or that have
contributed information to the Data Sheet, are cited here.
4. Methods and sources of information
Much of the data for this volume were gathered some years ago by Steven J. Falk, and details of the
sources of his information are given in Section 1 of A review of the scarce and threatened flies of Great
Britain (Part 1) (Falk 1991). These included post-1960 issues of the major British entomological
journals, major museums known to possess significant Diptera collections, various Diptera Recording
Schemes, and also the personal records of a large number of individual dipterists.
During this revision copies of the original data sheets have been up-dated by reference to national
journals, notably Dipterists Digest, Entomologist’s monthly Magazine, Entomologist’s Record and
Journal of Variation, Entomologist’s Gazette and the British Journal of Entomology and Natural History
in addition to the many published and unpublished sources detailed below.
Many records have accumulated from surveys undertaken by the Nature Conservancy Council (NCC) in
eastern England (the East Anglian Fens Invertebrate Survey; Lott, Procter & Foster 2002), in Wales (the
Welsh Peatland Invertebrate Survey; Holmes, P.R., Boyce, D.C. & Reed, D.K. 1991a, 1991b, 1991c,
1991d, 1991e, 1991f, 1991g, 1991, 1995a, 1995b, 1995c, 1995d, 1995e, 1995f), and at Savernake Forest
in Wiltshire and a variety of sites around Oxford. More recently the surveys carried out for the
Corporation of London at Burnham Beeches NNR, Buckinghamshire and Epping Forest, Essex have
produced many important records. The Countryside Council for Wales has also commissioned surveys of
ancient parks that have contributed records of Nematocera and Aschiza (Judd 1999a, 1999b; Levey &
Pavett 2000a, 2000b). All of these papers and reports have contributed data or background information
for this revision.
In addition, records submitted by dipterists who have attended the annual field meetings arranged in
connection with the Diptera Recording Schemes and more recently by Dipterists Forum have been made
available. These records cover many parts of Great Britain and they are now held by Dipterists Forum.
Recent publications from these meetings include Howe & Howe (2001) and Howe, Parker & Howe
(2001).
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