92 EPPING FOREST
remarkable form may be found commonly in
Monk Wood, small hairy tubular galls on the
upper surface of the beech leaves, greenish at
first and afterwards brown {Hormomyia piligera).
Another species affects the flowers of the Sneeze-
wort {Achillea ptarmica), and is interesting because
it was first observed in Essex in Epping Forest
{Hormomyia ptarmica, figured in Essex Naturalist,
i. p. 177). In some seasons it is common on
Fairmead.
The Diptera are a vast race (Britain contains
about 3000 species, of which probably one-half
occur in and around our forest), and it would be
manifestly impossible even to enumerate the tribes.
Epping Forest is almost unexplored in this de-
partment ; the only recent paper on the forest
species being that by Mr. E. Brunetti in the Essex
Naturalist for 1890. No one can overlook the
Diptera; they occur everywhere. Among the
families most likely to be noticed by the casual
observer are the Tipulidae (" Daddy Long-legs "),
of which several handsome species occur; the
larvae feed on rotten wood or roots of grass, and
are often extremely injurious to farmers in Essex ;
and the Syrphidae, or " Hoverer-flies," excessively
active, brightly coloured creatures, common in the
woods and lanes ; many of the larvae are Aphis
eaters. The great family of the Muscidae can
only be mentioned—to this belong many of the
commonest of known insects, including the House-
fly and the Flesh-flies, but the group is very obscure
and difficult to study. The grubs of certain
species of the group Tachininae are internal
parasites of the larvae of moths, and greatly aid
the Ichneumons in keeping in check some of the
larger caterpillars. Some Diptera in their early
stages are leaf-miners; one cannot walk in the
forest without noticing how profusely the leaves of
the hollies are blotched with the whitish-looking
mines of a species of Phytomyza; the larvae can
readily be found inside the burrows.
The Neuroptera (net-winged insects) are well
represented, and quite two-thirds of the British