Insects, etc., Injurious to Currants. 



231 



THE CURRANT GALL MITE. 



{Ei-iophyex ribis. Nalepa.) 



The disease caused by this mite is popularly called " Big Bud." 



During recent years the mite has become one of the worst pests 

 with which the fruit-grower has to reckon, the damage done is 

 enormous, and no means of extermination has yet been found. 



The difficulty experienced in. getting rid of the disease is due 

 entirely to the position of 

 the mites inside the buds. 

 Although, thanks to the 

 work of Newstead (1), 

 Lewis (2), and Warbur- 

 ton (3), we know a great 

 deal about the life-history, 

 yet there are still many 

 points upon which we have 

 not yet sufficient knowledge. 

 The minute mite that causes 

 the disease belongs to a 

 family of acari now known 

 as the Eriophyidci'., formerly 

 as Phytoptidcc. 



Other mites which be- 

 long to this family are pro- 

 tected by the bud in a 

 similar way : the Nut Bud 

 Mite (E. avellance, Amerl.), 

 the Birch Mite, E. rudis 

 (sub. sp. typicus) (Can.) and 

 the Yew Mite (E. taxi, 

 Murray), all of which cause 

 the buds to swell in the 

 same way as does E. riUs on the black currant. Galls are formed 

 by many of these mites on the leaves of various plants and trees, 

 such, for instance, as the several kinds of small red galls frequently 

 found in numbers on the leaves of the maple and sycamore, and the 

 common " nail galls " of the lime. 



They are usually situated on the upper surfaces of the leaves, the 

 aperture being below, and they may be covered inside with a whitish 

 downy substance. Mites belonging to this family attack other fruit 



[A. V. D. Rintoul. 



FIG. 175. BLACK CURRANT SHOOTS, RIGHT ATTACKED BY 

 BCD MITES, LEFT NORMAL. 



