132 



The Galls of Essex ; a Contribution to a 



behind (when mature they fall at the least touch). There 

 are generally eight or ten galls on a leaf, occurring on each 

 side of the midrib, mostly in the angle of a side vein. The 

 larva lives in the gall throughout the winter, pupating therein 

 in the spring. Hormomyia piligera, H. Loew. 



QuERcus EoBUR, L. Root- 

 lets. The galls when single 

 are about as large as a hazel 

 nut, but they generally occur 

 in confused masses of five or 

 six together. The galls are 

 soft when recent, but soon be- 

 come hard and woody ; they 

 are round, oval, or reniform^ 

 pyriform when confluent, and 

 contain from three to nine 

 thin-walled, oval larva- cells, 

 which are yellowish on the 

 inside. The galls are mature 

 in the autumn, and the apte- 

 rous, ant-like gall-flies emerge 

 therefrom throughout the win- 

 ter. BioRmzA APTERA, Fabricius (Fig. 16) [agamous form of 

 Andricus (Biorhiza) terminalis] . 



QuERcus EoBUR, L. Root. This gall generally occurs just 

 below the surface, where the roots leave the trunk, and is 

 mostly considerably larger than the preceding. It is round, 

 rough, hard, and woody, varying in colour with the surrounding 

 soil from light yellow or reddish to almost black ; it somewhat 

 resembles a truffle. In section the gall shows numerous oval 

 larva-cells embedded in its parenchyma. The gall is mature 

 in autumn, and the gall-flies emerge therefrom in April. 

 x\pHiLOTHRix RADicis, Fabricius (Fig. 17) [agamous form of 

 Andricus noduli] . 



QuERcus RoBUR, L. Bark. The gall is tooth- or rather 

 nail-like in shape, and is found deeply embedded in the 

 trunks of old oaks, frequently on the bark encircling the spot 

 where a large branch has been removed on old poHards. 



Fig. 16. Biorliiza aptera. 



