List of the Insect Fauna of the County. 145
in June, just before the catkins fall. Spathegaster baccarum,
Linne. (Fig. 42.)
Fig. 42. Spathegaster baccarum.
Quercus Robur, L. Leaf. This

gall resembles green
leaf-specimens of the former species
(S. baccarum) in every respect, ex-
cept that its surface is thickly
covered with fine, soft, whitish
hairs. The gall is mature in early
summer, and the gall-fly emerges
therefrom in July and August.
Spathegaster tricolor, Hartig.

(Fig. 48.)
Fig. 43. Spathegaster tricolor.
Quercus Robur, L. Leaf. The
small gall of this species occurs at
the margin of the young leaf,
generally near its base. It is
smooth, oval, and yellowish, some-
what resembling a white mustard
seed, except in shape (which is
more oval). The gall, which is
single-celled and thin-walled, is

mature in spring, and the gall-

Fig. 44. Spathegaster albipes.
fly emerges therefrom in June.
Spathegaster albipes, Schenck. (Fig. 44.)