Since 1980. L. depressa has heen recorded from scattered sites in twenty-nine 10 km.
squares throughout west, south, central and north-east Essex. It is still common in the
Epping Forest ponds, and occurs at gravel pits, ornamental lakes, farm reservoirs and
even garden ponds. It is, nevertheless, somewhat local, and appears to be a rarity in the
north-west of the county.
Libellula quadrimaculata (Linne, 1758) Four-spotted Chaser
This species is distinguished from all other similar species (such as females or
immature males of Orthetrum cancellatum, Libellula fulva and Libellula depressa) by the
presence of a dark spot at the nodus (mid-way along the leading edge) of each wing
(hence its popular and scientific name). Both sexes are predominantly yellowish brown
in colour, with black tips to the abdomen. There is no blue pruinescence on the male
abdomen (in contrast to the three similar species mentioned above). A variety with
additional dark patches at the tips of the wings is termed f. praenubila (Newman), and
was believed by both Edward Doubleday (1835) and Edward Newman (1832-3) to be a
separate species. Vander Linden's view that it was a mere variety subsequently
prevailed. In behaviour. L. quadrimaculata is a typical darter, resting on a favourite
perch over a pond or ditch, from which it makes regular sorties in search of flying insect-
prey returning again and again to the same perch. In July 1984 a fully adult individual of
this species was found hopelessly entangled in a spider's web at one of its Essex
localities. This is the largest and most powerful species that I have observed to be taken
by spiders.
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