Galls caused by the larvae, nymphs, and imagines of 

 Eriophyes axillaris 



on 



the leaves of Alnus glutinosa Linn. 



PLATE 48. 

 Synonymy of Mite. 



Ef'ineuni axillarc Schl. 

 Pliytoptus ahiicola Canes. 



„ altii Fock. 



Eriophyes Nalepi Fock. 



„ lavis Nal. 



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. — In the a.xils of the primary off- 

 shoots from the mid-rib. 



Manner of Gro\VTH.— Always in pairs ; glabrous ; glossy ; 

 globular ; ovid ; and reniform. 



Colour. — Yellowish green, red, dark brown. 

 Average Dimensions of a Mature Specimen (reniform 

 or ovid). 

 Height, 3 mm. ; length, 5 mm. ; breadth, 3 mm. 



May be sought during the months of June to October. 

 The Growth is complete by the end of August. 



These galls are remarkable in that they never occur on 

 any other part of the leaf than in the axils of the primary 

 offshoots from the mid-rib, and the bulging is always on the 

 upper surface. The surface of the gall is smooth, but under 

 magnification it is seen to be divided into sections of irregular 

 size owing to cerebriformal markings. The gall is hollow, 

 containing a considerable number of hairs of a reddish colour, 

 many of which project for some distance through the opening 

 in the under surface of the leaf 



The illustration is of specimens gathered at Hastings by 

 the author. 



128 



