1908.] Currant Bud Mite and Hazel Bud Mite. 677 



Every" now and again there is a recurrence of the statement 

 of the belief that the Hazel Bud Mite (E. avellance) can pass to, 

 live in and cause to swell, the buds of the black currant, and 

 that thus black currant bushes may become infected from 

 neighbouring hazel or nut trees. This is an echo of an old 

 controversy dating from early in last century, when workers 

 on these mites joined issue with one another as to whether the 

 same mite could make more than one kind of gall ; or give 

 rise to a gall on one plant and no gall on a different kind of 

 plant ; or whether the same species of mite could be found in 

 the same kind of gall on plants with little relationship to one 

 another. Thus the same mite was recorded as found in one 

 kind of gall on the leaves of the lime tree and on the willow 

 and in the swollen buds of the hazel. 



The difficulties and disputes have been due partly to faulty 

 observation ; to insufficient magnification of the mites before 

 the perfecting of the compound microscope ; to the extreme 

 minuteness of the mites — for only a few of them reach one- 

 hundredth part of an inch in length, and to the difficulty of the 

 characters, which are made the basis of distinction and separa- 

 tion of species — such characters as the number of bristles, the 

 position of the bristles, the sculpturing and striations of the 

 dorsal shield, and the shape of the ventral plate. 



The great worker in recent years on the genus Eriophyes is 

 Nalepa of Vienna, who has given detailed descriptions and 

 figures of many species. From Nalepa's work the Black 

 Currant Bud Mite and the Hazel Bud Mite stand as valid and 

 separate species. As far as I know there are no records beyond 

 dispute of the Black Currant Mite having been found in swollen 

 buds of the hazel, although Mr. W. E. Collinge has recorded* 

 finding on two occasions in black currant buds infested with the 

 Black Currant Bud Mite a few examples of the Hazel Bud Mite. 

 Mr. Cecil War burton, with hazel mite common in his garden, 

 has never found any in his black currants. An occasional 

 avellance found in black currant buds proves nothing. What 

 requires to be proved is that " big bud " in currants has been 

 due to E. avellance. It must be remembered that identiflca- ; 

 tion of the two mites needs a high power of the microscope. 



* Proceedings of the Association of Economic Biologists, Vol. I, July, 1 905, 

 p. II. 



