The first account of threatened British Diptera was included in Shirt (1987). This listed 827 Diptera, 270 as Endangered, 226 as Vulnerable, 328 as Rare and 3 as Appendix (extinct). Data sheets were included for 82 species (35 Endangered, and 47 Vulnerable), of which two were Empidoidea (Syneches muscarius (F.) and Poecilobothrus ducalis (Loew)). This was followed by the publication of A review of the scarce and threatened flies of Great Britain(Part 1) (Falk 1991). This presented species accounts of threatened species from the better-known families of British Diptera, together with a list of all British flies provisionally assigned to Red Data Book and Nationally Notable (now termed Nationally Scarce) categories.

 

This present volume deals with the Superfamily Empidoidea as defined by Chvála (1983), which total 673 British species in the latest Diptera check list (Chandler 1998a), now increased to 677 species (as of March 2003; Stubbs (2003)). The Empidoidea comprise five families (Atelestidae, Dolichopodidae, Empididae, Hybotidae, and Microphoridae), the species included representing approximately 10% of our Diptera fauna. The remaining families of Diptera outside of the Empidoidea that were not dealt with by Falk (1991) are reviewed in three further parts within the JNCC Species Status Review series.

 

Although less well-known than some of the more popular families of Diptera, the Empidoidea has attracted the interest of a growing number of dipterists in recent years. This has resulted in greatly increased recording effort, which is continuing under the auspices of the national recording scheme for Empidoidea (see the Biological Records Centre website at: http://www.brc.ac.uk/). The Empidoidea are found as adults throughout the spring, summer and autumn, with the greatest number of Empididae and Hybotidae found in early June (Plant 2003). The phenology can differ greatly between individual species and is summarised in the identification guides, but is not considered in this review. The adults are typically predators of other small insects, but they may also feed at flowers, with some species apparently showing preferences for certain plants (for instance, see Allen, 1994). Stark (1994) reviewed the prey composition and hunting behaviour of Platypalpus species. Pollet and Grootaert (1994) investigated the consequences of using different colours and heights of water traps upon the species collected.

 

The status of many species as proposed by Falk (1991) has been revised during the preparation of this volume. Initially, the Red Data Book and Notable categories (as defined by Parsons 1993) were used for this revision. Subsequently, following the adoption of the revised IUCN Guidelines (IUCN 1994) by JNCC in 1995, a further revision of the status for all species was carried out by Ian McLean (JNCC) in 2003. At the same time the nomenclature was brought up to date in accordance with the latest checklist for British Diptera (Chandler 1998a) and recent literature up to 2004 has been incorporated within the introductory sections and in the species accounts.