ERIOPHYID.E OR GALL-MITES. 



25 



Eriophyes rudis, Canest., on the leaf-buds of Betula alba. 



Synonymy of mite (Connold) : 



Phyioptus rudis, Canestrini. 

 Phytoptus calycophthinis, Nalepa. 



In fig. 24 two swollen buds on birch are represented. They were 

 found in High Legh, Cheshire, and cut from the same branch, and 

 in close proximity to a " witches'-broom " that peculiar bird-nest-like 

 appearance seen on birch and horn- 

 beam, of the growth and development 

 of which Miss Ormerod gives a very 

 interesting account, from personal ob- 

 servations made during 1876 and 1877, 

 while resident in the neighbourhood of 

 Isle worth. 1 There is no doubt, from 

 the description and illustration given 

 by her, and more especially from the 

 appearance of the actual branch itself, 

 seen in the South Kensington Museum, 

 that the abnormal branch growths were 

 heavily covered with swollen buds in- 

 fested by Eriophyinaa. 



I had, in consequence of Miss 

 Ormerod's description, for a long time 

 examined many " witches' - brooms," 

 without finding a single " blind bud." 

 The accompanying figure shows the 

 first infested buds I discovered in any way closely associated with 

 a "bird's nest." The orthodox opinion as to the cause of "witches'- 

 broom " or " bird's nest " is that it results from a fungus inhabiting 

 the tissues, known as Exoascus. 



With reference to " witches'-broom " being the result of fungal 

 growth, Tubeuf, speaking of experimental infection, says : 



" In the case of the Exoascese, two points were cleared by the aid 

 of artificial infection, the penetration of spores into leaves of host- 

 plants, and the production of witches'-brooms. Sadebeck, by means 

 of infectious Exoascus epiphyllus on Alnus incana, has produced 



1 Manual of Injurious Insects. Second edition. 



Fig. 21. Abortive siculloi buds caused 

 by Eriophyes rudis on birch. 



