34 



FOREST ENTOMOLOGY. 



upper surface of the leaves of the common sycamore (fig. 37). It is 

 now known by the name of Phyllocoptes acericola, Nal., and Connold 

 gives the following synonymy viz. : 



Phyllocoptes acericola, Nal. 

 Volvulifex aeeris, Amer. 

 Ceratoneon vuhjare, Bremi. 

 Phytoptus aeeris, Murray. 



The galls are very common on the upper surface of the leaves of 

 sycamore {Acer p>seudo-p>latanus). In some instances they are very 



thinly scattered over the leaf, in other cases 

 quite gregarious. They are very beautiful in 

 colour, varying from orange - yellow to purple. 

 They appear soon after the leaves develop, and 

 may be found throughout the 

 whole summer season. 



Such are a few typical speci- 

 mens of arboreal Eriophyidas 

 living in buds or forming 

 galls ; and, as just stated, 

 there may be many found on 

 trees, but with the exception 

 of two species viz., those on 

 hazel and yew they are not 

 very destructive, and certainly 

 not to be compared with the 

 species on black currant. 

 From the foregoing remarks it will be seen that the study of 

 Eriophyidse is purely a microscopical one. The bases of classification 

 are so minute, and the points of discrimination so difficult to deter- 

 mine, that the question naturally and suggestively arises whether 

 we have the same or different species of mite doing several kinds 

 of injury. As bearing on the specific differences of mites found on 

 different food-plants, I may say, from practical and local examinations, 

 that I have only once found Eriopliyes ribis on black currant in 

 Northumberland, near Newcastle-on-Tyne, whereas the species on 

 hazel is about as common as in Cheshire, where E. ribis is a direful 

 pest. Hence it would conclusively appear that the mites on the 



Fig. 36. Phyllocoptes carpini. 



a, dorsal surface ; 6, side view. (Copied from 



Nalepa.) 



