ERIOPHYID.^ OR GALL-MITES. 



Eriophyes eudis, Canest., on the leaf-buds oi Betula alha. 



Synonymy of mite (Connold) : — 



Plvjiopfus rudis, Canestrini. 

 Phijtoptus caJijcojjhfhirHS, Nalepa. 



In fig. 24 four 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 

 Isleworth.^ 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 Eriophyina\ 



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 Exoasceae, t»\vo 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 ejnphylhis on Alnus incana, has produced 

 ^ Manual of Injurious Insects. Second edition. 



Fig. 24. — Abortive swollen buds ca 

 hy Eriophyes rudis on birch. 



