44 BRITISH GALLS 



Economic Notes 



There are not many troublesome pests amongst the gall- 

 causing Hymenoptera; the attacks of the great majority 

 are confined to uncultivated plants. Some representatives 

 which are not gall-causers often cause damage in other 

 ways ; we may mention Nematus nhesii Curtis, which 

 defoliates gooseberry and currant bushes ; Lophyrus pini 

 Curtis, which eats the leaves of the Scotch Pine; Athalia 

 spinanim Fabr., which occasionally plays havoc in turnip 

 fields ; and Cephus pygmaeus Linn., which attacks the stems 

 of various cereals and grasses. 



Two gall-causing Cynipidae are alluded to in Miss 

 Ormerod's Manual — viz., Cynips Kollari and Neuroterus 

 lenticularis. " With the exception of the marble gall and 

 the common spangle galls, which sometimes so completely 

 load the back of the leaves as to cause premature withering, 

 it does not appear that any kinds are often materially 

 hurtful." We have had abundant evidence, though, during 

 the past summer (igii), of the destructive influences of the 

 so-called " oyster " gall, caused by the presence of the 

 larvae of Andricus ostreus. Quite early in the summer the 

 leaves of Quercus pedunculata in many districts showed 

 marked peripheral browning. The conditions they pre- 

 sented are well shown in Plate I., Figs, i and 2, which 

 show respectively the upper and lower surface of a leaf 

 gathered on August 23, when many of its galls had fallen 

 away. In the Haslemere district the majority of the trees 

 shed their leaves prematurely, and it cannot be doubted 

 that their growth was seriously checked. Cameron remarks* 

 concerning Cynips Kollari : " Various attempts have been 

 made to utilize these galls for ink- making purposes, but 

 without any practical result, owing to the paucity of tannic 

 acid they contain as opposed to the Aleppo and other galls 

 — only some 17 as against over 50 per cent. The only 

 use made of them is for ornamenting fancy baskets, fern- 

 * "British Phytophagous Hymenoptera," iv., p. 113. 



