PLATE 16. 



A twig of Betula alba Linn. 



(Nearly one-third nat. size.) 

 Galled by 



Eriophyes rndis Canest. 



The specimen illustrated on opposite page is, perhaps, the 

 most usual shape these galls affect. 



The attacks of the thousands of mites which swarm upon 

 them cause the twigs to grow outwards in all directions, and the 

 common centre to form into a hard, solid, and woody core. 



Some specimens, relatively to their size, are very heavy, and 

 cause the bough to bend downwards considerably. 



The i2-in. measure will assist the reader to form an idea of 

 the natural size. 



The illustration is of a specimen gathered at Hastings by 

 Harold Connold. 



