146 



The Galls of Essex ; a Contrihution to a 



Fig. 45. Spathegaster vesicatrix. 



QuERcus RoBUR, L. Leaf. This iucouspiciious blister- 

 gall occurs as a circular swelling of the leaf on both sides. 

 The mature gall is about 

 one -eighth of an inch 

 across, by about one- 

 twentieth thick, and is 

 yellow in colour, but is 

 green, like the leaf, when 

 immature ; on the upper 

 side radiate striations are 

 frequently noticeable. The 

 gall is mature in spring, 

 and the gall-fly emerges 

 therefrom in June. Spathe- 

 gaster VE SIC ATRix , S chlech - 

 tendal. (Fig. 45 j. 



QuEEcusRoBURjL. Male 

 flowers. In May and June 

 we often notice, as it were, 

 small locks of sheep's wool 

 in the oak trees, where no 

 sheep could get. These 

 are the galls of A. ramuIL 

 The gall is really a hard, 

 woody , irregularly- shaped 

 mass, consisting of many 



confluent larva-cells ; but its whole small surface is covered 

 with this thickly-matted, yellowish-white, woolly growth, so 

 that the mass is often as large as a walnut or small apple. 

 The gall is attached to a catkin ; it is mature in June, and is 

 many-celled, the gall-flies emerging therefrom in June and 

 July. Andricus ramuli, Linne. (Fig. 46.) 



QuERcus RoBUR, L. Male flowers. Small, oviform, rarely 

 almost spherical, smooth, but more or less deeply ribbed 

 longitudinally according to their stage of maturity, brown, 

 greenish-brown or reddish, succulent galls, occurring in some 

 numbers on a catkin-stem ; they are mostly sessile, but 

 occasionally have a short footstalk, which rarely is found 



Fig. 46. Andricus ramuli. 



