The Essex Naturalist
69
Wood ant colonies are still numerous in a number of woods in south-east
Essex where coppicing has maintained a cycle of open conditions preferred by
the ant. In these woods the nests are often obvious and important features and
the ants are so numerous that their potential effect on other invertebrates and
the ecology of the wood is obvious.
Although the main diet is aphid honey dew over 30% of the normal colony
diet will consist of arthropods and these ants have long been considered to play
an important role in regulating foliage feeding of forest trees. However the ants
are seldom evenly distributed throughout a forest area and any insect, arthropod
or earthworm is taken back as food including beneficial predators (Collingwood,
1979).
Rooks have been observed using the formic acid attacks of wood ant workers
to help kill their parasites and the short-term discomfort suffered by the birds is
evidently worthwhile.
Many arthropods have a more or less obligate association with ants. The blind
Woodlouse Platyarthrus hoffmanseggi is quite widespread in Essex in the nests of
Lasius niger, L. flavus and Myrmica species. The Woodlouse probably feeds on
pellets regurgitated by its hosts (Williams and Franks in Hopkin 1991).
Broom Hill is the site of the only post-1970 British record of the bethylid
wasp Pseudisobrachium subcyaneum which has an association with ants. It is not
known whether the larvae feed on the ant larvae or those of commensal beetles.
Associations with Ponera coarctata, Tetramorium caespitum, Myrmecina
graminicola and Formica exsecta are recorded (Burn in Edwards, 1998).
At Orsett Golf Course where an astonishingly rich ant fauna survives in
abundance in the ancient grass heath and gorse scrub of the old Mucking Heath,
a number of species of rove beetle with known associations with ants have been
recorded including Drusilla canaliculata, the Nationally Scarce (Na) Lamprinodes
saginatus, and the Local Zyros limbatus and Platydracus stercorarius (all det. A.
Williams). Whilst the situation at this site appears to be unique in Essex, our
knowledge of the communities elsewhere in the county is poorly known and a
thorough study at some of our best ant sites would undoubtedly uncover much
important information.
Conservation status of species in Essex
The audit of our biological resources and selection of species most in need of
conservation is fundamental to the biodiversity planning process and is urgently
needed for Essex and other parts of south-eastern England where modern
farming techniques and development pressures have decimated so much of our
wildlife habitat. Invertebrates remain generally neglected in informing the
nature conservation importance of sites and their management despite their
importance in ecological terms and their value in assessing habitat quality.
Happily there are signs that this is finally changing. The identification on a