2) Hemiptera. Dr. Peter Kirby
Heteroptera
There are rather few species of Heteroptera for which elm is the sole or a major host plant, but
a rather larger number of more generalist species may occur on it.
The most interesting of the species exclusively associated with elm is the flower bug
Anthocoris gallarum-ulmi. It feeds on the aphids Eriosoma ulmi, which form leaf-curl galls on
elm leaves. The nymphs of A. gallarum-ulmi are found only within the galls, but adults wander
from the galls from time to time during the summer, and also to hibernate. Though a little local,
this bug seems to be widely distributed and frequent in Essex.
Two close relatives of Anthocoris gallarum-ulmi are more or less common on elm: A.
nemoralis and A. confusus are predacious, and occur on a wide range of trees and shrubs. A
further member of the genus, A. nemorum, is characteristically a species of low herbaceous
vegetation, but not infrequently turns up on the lower branches of trees and shrubs. All of these
species can sometimes be found within the leaf galls occupied by A. gallarum-ulmi.
Most bugs which occur on the foliage of trees and bushes generally are members of the
family Miridae, the Capsids. Elm is no exception to the general rule. Most of the species which
can be found occur on a number of tree and shrub species, and are at least partly predacious.
Perhaps the most frequent of such species on elm in Essex are Campyloneura virgula, a small
delicate parthenogenetic species rather boldly coloured in grey, yellow and red, and Malacocoris
chlorizans an equally delicate species of mottled green. Both seemingly prefer bushes and low
trees.
The elongate green Blepharidopterus angulatus and the short-oval brownish Deraeocoris
lutescens prefer taller shrubs and trees, and neither are particularly frequent on elm: B. angulatus
is much more common on ash, alder and birch and D. lutescens is perhaps more frequent on
oak. Orthops cervinus occurs in small numbers on almost any woody vegetation, but shows a
preference for those plants which flower in midsummer. Heterotoma meriopterum is a shining
black elongate bug with green legs and strikingly enlarged antennae, which is found generally
on low bushes and rank tall herbs. It can occur in considerable numbers on elm in scrub and
hedgerows, quite often in company with the green bug Lygocoris pabulinus, which lays
overwintering eggs in a range of woody hosts, and has a summer generation on various
herbaceous species. A number of other generalist species can occur more or less incidentally
on elm in situations where there are low branches intermingled with rank herbaceous vegetation.
The pale green Orthotylus prasinus is confined to elm. It is perhaps a little local, and its
presence cannot be guaranteed on any given patch of elm, but it is probably well established
throughout the county. Two related species are also to be found on elm. Elm is a major host
of O. viridinervis, a somewhat larger and darker species than O. prasinus. O. ochrotrichus is
very similar to O. prasinus. It is a generalist species, usually found on low-growing woody
plants.
Elm is also a major host of Calocoris fulvomaculatus, a medium sized brownish species,
partly predacious. Formerly a pest of hops, it is now rather local, and is found particularly along
hedgerows and around the margins of scrub. The related Miris striatus is a spectacularly marked
large Capsid, velvet black with red legs and longitudinal yellow lines. It is usually found on oak
or hawthorn, but has been recorded from several other trees including elm. The bug is quite
frequent, though local, in Essex.
Capsid bugs of the genus Phytocoris are long-legged predacious insects which are cryptically
coloured in mottled browns or greys. The commoner tree-dwelling species are typically to be
found on trunks, branches and twigs. Here they rest with the legs folded in and the body pressed
close to the substrate, so that they are almost indistinguishable from the bark. Several species
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