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Grange Farm, Chigwell: an important site for arboreal Coleoptera
and other invertebrates
JONTY DENTON
2 Sandown Close, Alton, Hampshire GU34 2TG
Introduction
The key habitats at Grange Farm (approximately TQ4495) arc a complex of unmanaged hedgerows,
bordering rough pasture fields which have remained unmanaged for at least five years. The area was
visited and sampled using standard field techniques (beating, sweeping etc.) on four occasions between
2nd and 20th July 1998 and again in June 1999.
Mature oak frees were abundant, with Field Maple and a few large Beech trees. Elm was also abundant,
with dead, dying and healthy stands in similar proportions. Some of the oaks were clearly very old.
although many of the rarer insects were found on fairly small, gnarled and twisted trees. Around a
dozen had red-rotten wood exposed, and two of these supported the arboreal ant Lasius brunneus
(Latreille) (Notable A). Nests of the ant Leptothorax nylanderi (Foerster) were found inside a dried-
out bracket fungus on a branch at ground level, and under a small piece of bark on a fallen branch.
This species is invariably found in areas withi. brunneus.
The local brown lacewing Nothochrysa capitata (F.) was beaten from a large oak, and the Notable
arboreal spiders Philodromus albidus Kulczynski and P. praedatus O.P.-Cambridge were abundant
on the lower branches of elm and oak. Suckering elms also supported the Notable hopper Macropsis
mendax (Fieber).
The Notable ground beetles Pangaeus bipustulata (F.) and Platyderus ruficollis (Marsham) were
found on derelict ground nearby, and a Notable (though rapidly spreading) weevil Hypera meles (F.)
was added to the list in 1999. Further, if somewhat surprising, invertebrate interest turned up in old
but artificial water bodies on the site, in which the Notable water beetles Hydaticus seminiger (Degeer).
Rhantus suturalis (MacLeay) and Helochares lividus (Forster) were collected.
The most remarkable feature of the site, however, was the number of scarce arboreal Coleoptera,
details of which are presented in Table 1 .The longhorn beetle Gracilia minuta (F.) was found on the
cut ends of Bramble stems which represents the first modern record of this RDB2 species in Essex.
Measuring the site's importance for arboreal Coleoptera
A species quality score (SQS) and species quality index (SQI) were calculated using the criteria
outlined by Fowles (1997). The SQS of 208 is not in itself exceptional; however, as only fifty
species of saproxylic beetles (including common species) were recorded, the SQI of 4.16 better
reflects the quality of the site. Fowles (1997) suggests a SQI of over 300 indicates an 'outstanding
site for saproxylic Coleoptera'. The index of ecological continuity (IEC) (Alexander 1988) of 16
was also impressive from such a brief sampling period and small number of old trees.
Essex Naturalist (New Series) 17 (2000)