Galls caused by the larvae, nymphs, and imagines of 

 Eriophyes laevis Nal. 



on 



the leaves of Alnus glutinosa Linn. 



PLATE 54. 

 Synonymy of Mite. 



Phytoptus Icsvis Nalepa. 

 Cephaloneon pustulatum Biemi. 



Habitat of the Alder. — Abundant in Britain by the sides 

 of streams, in woods where the ground is wet and swampy, 

 and occasionally in more accessible places. 



Position of the Galls.— On the upper surface of the leaves. 



Manner of Growth. — Gregarious ; glabrous; glossy; more 

 or less globular and pedunculated. 



Colour. — Green, yellow, orange-yellow, bright red, purple, 

 chocolate-brown. 



Average Dimensions of a Mature Specimen. 

 Height, 2 mm. ; girth, 4 mm. 



May be sought during the months of May to October. 



The Growth is complete by the end of August. 



A little below the centre of the illustration are three galled 

 leaves, the finest specimens possible to obtain. So numerous 

 are the galls upon each leaf that, owing to the swelling of their 

 globular portion, the blade of the leaf has been caused to bend 

 under until a pouch has been formed. Several other leaves are 

 so curved that the galls are seen silhouetted against the back- 

 ground, furnishing an excellent description of the shapes they 

 assume. These galls are extremely plentiful in many places ; 

 some trees are loaded with them year after year. A leaf of 

 average size may have as many as 400 galls upon it. 



The illustration is of specimens gathered at Hastings by the 

 author. 



140 



