134 



The Galls of Easex ; a Cuntrihutiun to a 



branches of trees. Tliey are hard, conical, single-celled 

 galls, coarsely furrowed on their basal two-thirds. They 

 never occur singly, and when fresh the galls are deep red in 





Fig. 19. Aphilothrix Siehohlii. 



colour, which tint they lose after the emergence of the insect. 

 The galls are mature in September, and the gall-flies emerge 

 therefrom in April or May. Aphilothrix Sieboldii, Hartig 

 (Fig. 19) [agamous form of Andricus testaceipes] . 



QuERcusEoBUR, L. Stem. The 

 galls are soft, succulent and berry- 

 like, occurring on the trunks of 

 young oaks. They are spherical, 

 pea- sized, bright red or yellowish, 

 and single- celled. The galls, 

 which mature very quickly, really p^j. 20. Trii 

 occur on the stem-buds of the 

 oaks in the spring ; they soon shrivel up and disappear after 

 the emergence of the gall-fly, which takes place in June. 

 Trigonaspis megaptera, Panzer. (Fig. 20). 



QuERcus RoBUR, L. Twig. Little, glabrous, oval swellings 

 are frequently noticeable on the bark of oak-twigs, more 

 especially when pierced by the gall-flies ; these are the galls 

 of Andricus nodali. This single-celled gall also occurs on 



igonaspis meDaptera. 



