Galls caused by the larvae, nymphs, and imagines of 

 Eriophyes rudis Canest. 



on 



the leaf-buds of Betula alba Linn. 



PLATE 63. 

 Synonymy of Mite. 



Phytoptus rudis Canestrini. 



„ calycophthirus Nalepa. 



Habitat of the Common Birch.— Plentiful all over Britain 

 in parks, plantations, woods, and gardens. 



Position of the Gall.— On the twigs and branches. 



Manner of Growth. — Singly and in clusters ; pubescent 

 and glossy. 



Colour.— Outer leaflets dull brown, inner ones silvery grey. 



Average Dimensions of a Mature Specimen (a single 

 bud). 

 Height, ID mm. ; girth, 27 mm. 



May be sought during any month in the year. 



The Growth is complete by the end of August. 



The galls are very numerous, and occur in clusters of con- 

 siderable numbers. They develop into three principal forms: 

 {a) at the termination of a twig with a hard, solid, and 

 woody core, from which numerous twigs project, as shown in 

 plate 16; ij)) from any part of a twig or branch, and without 

 any core, as shown in plate 17 ; {c) from the side of a branch 

 with a hard, solid, and woody core, which also forms a part of 

 the branch, as shown in plates 18, 19, and 20. 



The gall is also figured by Miss Ormerod, " Injurious Insects," 

 pp. 212, 214. 



The illustration is of specimens taken from the tree at 

 Guestling by the author. 



158 



