Galls caused by the larvae, nymphs, and imagines of 

 Eriophyes lionotus Nal. 



on 



the leaves of Betula alba Linn. 



PLATE 65. 

 Synonymy of Mite. 



Phytoptus leionotus (corr. lionotus) Nal. 

 Ceplialoneon betulinum Bremi. 

 Phyllermm [Erineuni) tortiiosuni Gerv. 



Habitat of the Common Birch.— Plentiful all over Britain 

 in parks, plantations, woods, and gardens. 



Position of the Galls. — In the nerve-axils of the leaf. 



Manner of Growth. — One in each axil ; generally six on 

 a leaf 



Colour. — Reddish brown on upper surface, reddish pubescence 

 on under surface. 



Average Dimensions of a Mature Specimen. 

 Height, 1 1 mm. ; length, 4 mm. ; breadth, 2 mm. 



May be sought during the months of May to October. 



The Growth is complete by the end of August. 



These galls are at first somewhat inconspicuous, but during 

 August they become very pronounced in outline, rising above 

 the level of the surrounding surface of the leaf-blade to a height 

 of 2 or 3 mm. They are mostly obtusely elliptical in outline, 

 and sometimes extend from one nerve-axil to the next beyond 

 it, the outline being then very irregular. The convexo-concave 

 swelling is filled with pubescence, which projects considerably, 

 and amongst it the mites may easily be seen under magnification. 



The illustration is of specimens gathered at Guestling, near 

 Hastings, by the author. 



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