hoppers belonging to the subfamily Typhlocybinae. Members of this group are generally rather
small, delicate insects which feed by piercing individual cells of the leaf mesophyll of their host
plants. The majority of the cloud of insects disturbed from elm is usually Ribautana ulmi, whose
general pale yellow colouration is varied by dark markings along some of the veins at the tip of
the wing, and often also on the head and forebody. In the south-west of the county the rather
smaller and plainer Edwardsiana ishidai seems not infrequently to be another component of the
cloud. Though seemingly quite frequent in this area, and perhaps elsewhere in Essex, it is an
uncommon insect nationally. Other members of the large genus Edwardsiana which can occur
on elm are E. hippocastani, E. plebeja and, less certainly, E. avellanae and E. lethierryi. All
have been recorded from Essex, though not necessarily from elm. Other Typhlocybines which
have been recorded from elm, but which have other host plants, are Alebra wahlbergi, common
on elm probably throughout the county; Typhlocyba bifasciata, Ribautiana tenerrima, Eu-
rhadina ribauti, Arboridia ribauti, Empoasca vitis and Alnetoidea alneti. Several other gener-
alist tree and shrub feeders might also occur on elm.
The largest of the Auchenorrhyncha regularly found on elm is the froghopper Aphrophora
alni. This is a sturdily-built insect up to a centimetre long, brown with pale markings on the
forewings. It is a common insect found on a wide range of woody plants besides elm.
Members of the subfamily Deltocephalinae feed mostly on grasses or low herbs. Several
species, however, occur particularly where such low plants grow in the vicinity of trees and
bushes, and the adults tend to move to the foliage of these woody plants. Five more or less
frequent species which may occur on elm in such circumstances in Essex are Thamnotettix
dilutior, T. confinis, Allygus mixtus, A. modestus and Speudotettix subfusculus, and one or two
other species may occur less commonly. Several members of the family Cixiidae, whose early
stages are subterranean, show a similar preference for the foliage of woody plants when adult.
The only two common members of the family in Essex, Cixius nervosus and Tachycixius pilosus,
can both be found on elm quite frequently.
Iassus scutellaris is a large green leafhopper, with brownish markings in the male, which
feeds only elm. It has only recently been recognised in Britain, having probably been previously
overlooked through its superficial similarity to a common oak-feeding species. It appears to be
a very local and restricted species, and has so far been recorded only from Surrey, Middlesex,
Kent and Essex. It is now known from several sites in the south-west of Essex, and is clearly
well established.
Macropsis mendax is a rather uncommon species nationally. It is a green or brown
leafhopper, confined to elm. It appears to have been rather commoner and more widely
distributed in the past, and may well have suffered as a result of elm disease. However, though
decidedly local in Essex there are several recent records which show that it is still quite well
established, and perfectly able to maintain viable populations on regenerating elm scrub.
Three British species of Auchenorrhyncha for which elm is the sole or a major host,
Macropsis glandacea, Zygina schneideri and Kyboasca bipunctata, have not yet been recorded
from Essex. K. bipunctata is apparently confined to elm in Britain. It has only recently been
added to the British list, and may be a recent colonist. It is so far known only from Surrey and
Kent. Z. schneideri is a very local species, but is quite widespread. Both species may eventually
prove to be present in Essex. M. glandacea is only known in Britain from two very old records
from Kent.
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