366 MR. C. WARBURTON AND MISS A. L. EMBLETON ON 
The Life-history of the Black-Currant Gall-mite, Eriophyes 
(Phytoptis) ridis, Westwood. By Crcim Warsurton, 
M.A., F.Z.S., Zoologist to the Royal Agricultural Society 
of England, and Atice L. Empxerton, B.Sc., 1851 Exhibition 
Science Research Scholar, Associate of the University of 
Wales (Cardiff College). | 
[Read 7th November, 1901.] 
(Piatzss 33 & 34.) 
Tue Black-Currant plant disease due to Eriophyes ribis first 
attracted attention in England in the year 1869, though the 
cause was not at first clearly ascertained. Since that time it 
bas been the subject of frequent references by economic ento- 
mologists, who have generally recorded the fact that the pest 
was on the increase. To this day, however, our knowledge of 
the life-history of the mite is extremely limited, and the state- 
ments of yarious observers with regard to it are either too vague 
and general to be of much practical value, or are absolutely 
inconsistent and conflicting. No complete account of its life- 
cycle has yet been attempted, and its methods of distribution 
have remained a matter of conjecture. 
The difficulty of the research is, of course, largely due to the 
minute size of the mite, which rarely exceeds one hundredth of 
an inch in length*. To observe and record the condition of the 
mites inside the buds at various seasons of the year is a tolerably 
simple matter, but a thorough investigation of their habits in- 
volved watching the creatures throughout their wanderings, and 
here their small size proved a serious obstacle. 
In a paper on “ Insects affecting the Orange” T, H. G. Hulbard 
described certain phenomena with regard to an allied mite which 
suggested to him that it owed its distribution largely to the aid 
of various insects and arachnids, and it was the clue thus afforded 
by him that was immediately responsible for the observations on 
distribution in the present investigation. 
* The measurements are:— 9, length ‘23 mm., breadth ‘04 mm. 
Gy, » L6 » 08 
t U.S. Dep. Agric. Ent. 1885. 
