List of the Insect Fauna of the County. 143
March. Neuroterus lenticularis, Olivier (Fig. 37) [agamous
form of Spathegaster baccarum] .
Fig. 37. Neuroterus lenticularis.
Quercus Robur, L. Leaf. This spangle-gall greatly re-
sembles the common spangle-gall last described, but in shape
it is raised from the surface
of the leaf at its margins ;
it is reddish or purplish in
colour, and does not gene-
rally occur in such im-
mense numbers on a leaf.
The gall-fly emerges from
the fallen gall in March.
Neuroterus fumipennis,
Hartig (Fig. 38) [agamous

form of Spathegaster tri-

Fr;. 38. Neuroterus fumipennis
color] .
Quercus Robur, L. Leaf. Another closely-allied spangle-
gall. It differs from the common species in shape, and in
being smaller and of a more yellowish or cream-colour; it is
a concave disc, with a small raised knob in the centre. The
accompanying figures of
an imaginary section of
each of these three closely-
allied spangle galls will

Fig. 39.
help in their differentia-
tion. In Fig. 39, α. repre-
sents N. fumipennis, β. N. laeviusculus, and γ. N. lenticularis.