62 CURRANT. 



The mites of the other families of the Acarina — as, for in- 

 stance, the Pied Spider of the Hop, the Tetranyclms telariiis — 

 are of a much rounder or more oval shape, hut are especially 

 distinguishahle hy their greater numher of legs. As a rule, 

 they possess three pairs when they are hatched and in their 

 earliest stage, hut, with subsequent moults, as they approach 

 maturity, they become possessed of four ]3airs. 



This point of the number of legs is a very important one to 

 observe, in order to prevent confusion in identification with 

 other kinds of mites which may very likely be found on 

 Currant bushes. 



Phytoptas ribis is of the shape figured at p. 60, that is, 

 long, narrow, cylindrical, somewhat tapering towards the 

 blunt tail, at the extremity of which, on each side, is one long 

 bristle, and there are also two other pairs of bristles one on 

 each side of the body — one pair near the fore part, the other 

 a little before the middle. The proboscis is short ; the four 

 legs are plainly jointed, and the abdomen with about seventy 

 punctate transverse rings. The length of the female is 0*23 

 millimeter, the breadth 0"04 millimeter- ; the dimensions of 

 the male are smaller.* 



The infestation is to be found on the Black Currant {Rihcs 

 nigrum) both in Great Britain and on the Continent of Europe. 

 Likewise occasionally (but not as yet, so far as we are aware, 

 in this country) on the Ked Currant {Ribes rubrum) and the 

 "Tasteless Mountain Currant" [Ribes aljnnum). In regard 

 to R. alpinwn, as this kind grows wild in some localities 

 both of England and Scotland, some investigation as to the 

 P. rihis being found on it might be worth while. 



From special observation of the habits of the Currant Bud 

 Mite, and more particularly those of Mr. Piobert Newstead, 

 referred to below,t we find that mites are present in the 

 swelled buds in the perfect condition in January, and not 

 apparently injured beyond being made temporarily somewhat 

 sluggish by severe frost. Eggs also are then present. In 

 February eggs may be found in great numbers in the galled 

 buds in company with the adult mites, and by March 6th 

 "there were thousands of young forms (nymphs), and eggs 

 and adults were also present." 



* For practical purposes it is enough to mention that the mites are so ex- 

 cessively small as to be indistinguishable to the naked eye. A millimeter is 

 the 25th part of an inch, and twenty-three hundredths of this measurement— 

 that is, somewhat less than a quarter — is scarcely perceptible except when 

 magnified. 



t "Recent Investigations of the Currant Bud Mite (Phyt02}tus ribis),'' by 

 R. Newstead, F.E.S., Curator of the Grosvenor Museum, Chester, Lecturer on 

 Economic Entomology for the Cheshire County Council, pp. 5-7. Reprinted 

 from ' The British l^turalist ' for June, 1894, Price 3d. 



