CUERANT GALL MITE. 61 



The deformed bud growths, which for many years have 

 been a source of great trouble to Black Currant growers, 

 are caused by an exceedingly minute mite, too small to be 

 seen by the naked eye, — scientifically Pliytoptiis rihis, — which 

 jDropagates in the buds, and causes an unnaturally large 

 development of these into spherical or somewhat oval soft 

 green knobs formed outside of greenish scales or abortive 

 leaves folding over each other, and inside of the various parts 

 which would gradually have developed into leaves, flowers, 

 and fruit, but contorted by the action of the mites into un- 

 natural condition, and abortive for any useful purpose. 



These "knobs" may be found forming during the winter 

 whilst the healthy buds are still of their natural shape, and 

 in January may be found up to as much as a quarter of an 

 inch in diameter, and containing within them numbers of the 

 mites and some eggs. Later on, growth of the gall knobs 

 continues until they may at times be found as large as some 

 specimens sent me from Toddington during the year 1897, 

 which proved to be for the most part from about three to 

 four-eighths of an inch in diameter, and, in the case of the 

 upper specimens on the twig, were dying and drying off into 

 the condition in which the mites leave them and emigrate to 

 set up attack in the still embryo buds in the axils of the 

 leaves. 



The first definite allusion to the presence of this Black 

 Currant bud disease being observed in England took place at 

 the meeting of the Scientific Committee of the Eoyal Horti- 

 cultural Society on March 2nd, 1869,* and the investigations 

 carried on showed that as a very injurious attack (though of 

 a nature of which the cause was not distinctly ascertained) 

 the disease had been known in the district of Blantyre, N.B., 

 for twenty years before the above date. 



The first notes that were sent to myself regarding this 

 infestation as a serious trouble were forwarded in March, 

 1885, and since then the attack has spread so widely both in 

 England and Scotland, and the measures for its extirpation 

 have proved of so very little more than mere temporary 

 service, that the matter has become one of grave importance 

 to all growers of Black Currants, especially where cultivation 

 is on the scale of field growing. 



Life-history. — Phytojytus ribis, or the Currant Bud Mite, 

 belongs to one of the divisions of the order Acarina, or mites, 

 but is distinguishable from all the other families by its more 

 or less elongate, cylindrical, or worm-like shajje, and also by 

 only possessing four legs througliout its lohole life. 



* See reports in ' Gardeners' Chronicle ' for 1869, p. 252, also p. 276. 



