THE BRITISH NATURALIST. 



133 



attempted to count the individuals in a single bud, but there must be 

 thousands of them, and it is by the constant irritation of these minute 

 organisms, probably aided by the secretion of some matter poisonous to 

 the plant tissues, that the buds become swollen and diseased. 



In the pamphlet issued by the Board of Agriculture [A 1 ~J? :; Feb. 

 1893] ^ is stated that the mites " stray about upon the leaves and 

 shoots, and as they make their peculiar gold-coloured galls upon the 

 young and tender twigs, as well as upon the sheathing scales or 

 embryonic leaves of the buds, it is believed that they live upon these." 

 The " gold-coloured galls " are perfectly natural growths ; they are the 

 fragrant oil glands, and are found upon the healthy as well as the 

 diseased plants. They are certainly not produced by the mites. 



LIFE HISTORY. 



The following notes were made from my own observation during the 

 past year : — During the cold month of January the mites in the infested 

 buds were all in the perfect condition, and although the temperature 

 was often very low, the mites revelled in the severest frost, as one 

 would in a cold bath on a summer's day. Frost seems to have no 

 effect on them whatever, except to make them somewhat sluggish. 

 True, they are well concealed within the buds, yet they cannot by this 

 means escape the frosts, for the buds offer very little protection for 

 their naked bodies, the fluid of which must be frost proof. On Feb. 

 20th egg laying commenced, and on this date I found them in 

 hundreds in company with the adult mites. Later (March 6th) there 

 were thousands of young forms (nymphs), eggs and adults ; and sixteen 

 days later (March 22nd) I examined flowers and expanded leaves. In 

 the flowers I found a single Phytoptus (mite), which was walking 

 about them in a very lively manner. As stated above, the normal 

 colour of the mite is a clear semi-opaque white, almost glassy, 

 but the specimen found in the flowers had the extremities reddish- 

 brown, with the centre paler. The red colour of the mite very much 

 puzzled me, and I at first thought it another species of Phytopti. A 

 careful microscopical examination, however, proved it the true P. ribis. 

 My time was too limited to search for more. Had I continued my 

 search, no doubt I should have found them in considerable numbers. 

 The discovery of a red coloured specimen was of interest to me, and no 

 doubt will be so to others, but it has no practical bearing on the 

 economy of the species. 



On April 19th many of the old and very badly infested buds of last 

 year had opened out very considerably, but had not produced, nor did 

 they afterwards produce, a single leaf. These and the rest of the infested 

 buds contained a living mass of the mites in all stages, completely 

 covering every embryo leaf in the buds. At this date numbers of the 



