The Essex Naturalist
61
The modern distribution of ants (Hymenoptera: Formicidae)
in Essex with their regional rarity and threat status
P.R. Harvey
32 Lodge Lane, Grays, Essex RM16 2YP.
Introduction
Provisional maps were published in the Essex Field Club Newsletter (Harvey,
1993) and there is an outline description of the species distribution in A
provisional list of the bees, wasps and ants (Hymenoptera: Aculeata) of Essex (Harvey
& Plant, 1996). Our knowledge of the distribution of ants is now reasonably good
in the county and whilst it is always possible to work towards a more thorough
coverage, the imminent onset of the new millennium and the dramatic national
declines shown by many invertebrates including aculeate Hymenoptera suggest
that a full account of the ant species with distribution maps will make a useful
contribution to our knowledge of the invertebrate fauna of Essex.
With the development of Local Biodiversity Action Plans there is a need for
information on the status of species at a regional level so that the importance of
sites can be properly assessed. This is a particular problem for invertebrates but
also one which is increasingly being addressed, for example in the form of
county Red Data Books which include invertebrates, such as the Dorset Red Data
Book (Mahon & Pearman, 1993) or those for specific invertebrate groups such
as aculeate Hymenoptera in Yorkshire (Archer, 1998). The process is here
undertaken for the ants of Essex and in the near future it is hoped to provide
similar information for the rest of the aculeate Hymenoptera and the Arachnida
(spiders, harvestsmen and pseudoscorpions). The author is grateful to CW.
Plant for helpful comments during the drafting of this paper.
Our knowledge of ants in Essex
Coverage of the county at the time of Barrett (1979) does not seem to have
been good and even common species are not well represented. Examples of the
dramatically improved knowledge on the Essex distribution of species include
the species Myrmica schencki and M. bessarabica (=specioides), neither of which
were recorded from the county at all at the time of Barrett. A total of thirty one
species has now been recorded for the county, of which one is introduced and
three are only known from old records.
The present distribution maps are the cumulation of nearly 4000 records
made since 1980 with most records in the period from 1986 to 1998. The bulk of
records have been made by the Essex Spider Group (R. Ruffell, D. Carr, K. Hill
and the author) in the course of their extensive fieldwork over much of Essex for
spiders. As well as records resulting from sweeping, direct observation, "grubbing
around" and sieving leaf litter many records have resulted from pitfall trapping.
Valuable records have also been provided by the local record centres at