Galls caused by the larvae, nymphs, and imagines of 

 Eriophyes brevitarsas Nal. 



on 



the leaves of AInus glutinosa Linn. 



PLATE 49. 



Synonymy of Mite. 



Erineum alneian Pers. 

 Phytoptus brevitarsus Nal. 



„ purpureum De C. 

 Phyllerium alnigenum Kunze. 

 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 blade of the leaf; irregu- 

 larly distributed. 



Manner of Growth. — Gregarious ; glabrous on upper surface, 

 slightly pubescent beneath. 



Colour. — Pale green, very pale yellow, ultimately turning 

 brown. 



Average Dimensions of a Mature Specimen. 



Height, 6 mm.; length, 18 mm.; breadth, 12 mm. 



May be sought during the months of June to October. 



The Growth is complete by the end of August. 



These galls cause considerable disfigurement of the leaf, and 

 are found mostly on the young and expanding leaves near 

 the end of the twig. They are convexo-concave, blister-like 

 swellings. The upper surface is smooth and glossy ; the interior 

 is slightly pubescent, the mites living therein. The blisters are 

 somewhat irregular in shape, but are mostly ovid. They are 

 not restricted to the areas enclosed between the primary and 

 secondary offshoots from the mid-rib, but they also involve the 

 mid-rib itself 



The illustration is of specimens gathered at Hastings by 

 the author. 



'3° 



