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. Aiiliilothrix 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. ApmLOTURix corticib, 



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- 



shoots of oak- stubs or the smaller 



¥m. 18. Aphilutlirix corticis. 



