List of the Insect Fauna of the County.
133
When young it is a smooth, succulent, rounded, greenish gall;
but when mature it is hard, brownish, really obconical in
shape, but on the surface presenting a circular convex lid
Fig. 17. Aphilothrix radicis.
which falls off when mature, showing the pierced, circular,
apical, woody septum of the gall surrounded with numerous
small, circular punctures, this just below the surface of the
bark. The galls are single-celled,
but generally occur gregariously ;
they are mature in autumn, and
the gall-flies emerge therefrom in
early spring. Aphilothrix corticis,
Linne (Fig. 18) [agamous form of
Andricus gemmatus, Adler] .
Quercus Robur, L. Bark. Small
acorn-like, red or brown galls occur-

ring in clusters on the young off-

Fig. 18. Aphilothrix corticis.
shoots of oak-stubs or the smaller