OF EPPING FOREST. 141
Gall.
Appears on the under-surface of the oak leaf (diameter
2-3 mm.) Colony: Yellowish to reddish. Shape: Irregular to
circular, cup-shaped and pointed in the centre; few or no hairs
present. Numerous on the leaf.
Imago.
Colour: Black. Thorax and Head; Smooth and shining. Abdomen:
Compressed and elongate. Antennae: Dark brown, 2 basal joints may be
yellowish. Legs: Dark brown. Apices of all the joints yellow. Wings:
Hyaline.
(2.) Sexual Generation IIa. Neuroterus albipes
(Schenck). Inquiline. Synergus apicalis (Htg.)
Gall.
Appears on the margins of the leaves, causing indentations,
and in some cases stunting them. Shape: Oval, may be some-
what pointed at the apex. Sessile on the leaf margin, Colour:
Yellow to yellowish green.
Imago.
Colour: Black. Antennae: Brownish. Basal 4-5 joints yellow. Third
joint slightly curved in the male. Thorax: Smooth and shining. Abdomen:
Shining and compressed. Ovipositor: Testaceous. Legs: Usually very light
yellow in colour. Coxae and bases of femora dark. Wings; Hyaline, nervures
pale.
Account of Generation Cycle.
The Neuroterus laeviusculis galls fall to the ground, like
N. lenticularis, in the Autumn. Moisture is also necessary for
them if they are to reach maturity.
Asexual flies emerge from them as a rule about the end of
March. These insects prick the oak buds at the end of March
or the beginning of April; the resulting galls, N. albipes, which
are small and hard, appear in May.
From the galls of N. albipes, sexual flies emerge at the end of
May, though often not until June. These flies oviposit on the
under-surface of the young and tender leaves, and in about three
weeks the galls of Neuroterus laeviusculi again appear.
OCCURRENCE IN EPPING FOREST.
The Neuroterus laeviusculus gall often has the edges curled over,
and may be very irregular in shape, in many cases bearing a
great resemblance to Neuroterus fumipennis. First appearance
noted August 12th. This gall was not so common as the
preceding. Neuroterus albipes, however, was very abundant, the
first appearance I noted being on May 18th. This gall I found
in a variety of situations, both on the petioles and on the leaves
themselves, causing them to become indented and to curl up.