69 



by Mr. Lewis, but I have never seen them this color myself. There 

 is no time during the year in which the reproductive powers are 

 checked as long as the weather is more or less congenial. Mr. Lewis 

 found the eggs fewest in December and January, but during the present 

 year they have been teeming in the buds during the first two weeks of 

 this month (December). No doubt frosty weather checks the repro- 

 ductive powers. Certainly the increase is most rapid from April to 

 October. When the buds burst in April, the Phytoptids may be seen 

 crawling outside, and as pointed out to me by Mr. Lewis, they attach 

 themselves by the anal sucker and wave their bodies and legs in the 

 air. Mr. Cecil Warburton states that they jump into the air. This 

 is extremely probable, but that they do so to chance falling on to a 

 passing insect so as to be distributed is very problematic. 



The life cycle can and does go on from year to year on the bush; 

 when a bud is killed or when it bursts the mites crawl out and make 

 their wa}^ to others. This is not all, however, for if we cut down a 

 bush that has been badly attacked we still find next year's shoots 

 showing traces of big-bud and the swollen buds occur low down the 

 shoots. This, I am sure, points to infection coming from the soil. 

 Whether eggs or mites or both retain their vitality in the earth I do 

 not know, but that they contaminate the soil I am fully convinced. 

 Hence we find hand picking and hard pruning only partly successful. 



Certain varieties are more susceptible than others, but none except 

 a light -cropping cottage black currant grown in Kent seem to be 

 immune. The Baldwin is the worst sufferer; then come Black Naples 

 and Black Dutch. Lee's Prolific is also attacked, but clean stock of 

 this kind can be procured. Carter's Champion is thought to show 

 some degree of immunity. I do not think any black currant will long- 

 resist this pest, which spreads rapidly, being distributed by men 

 walking in the plantations, the mite becoming attached to their clothes, 

 or in mud on their boots. Many no doubt are carried by the wind 

 and numbers by other insects, especially bees of the genus Audrena 

 and Bombus that visit the currants when in blossom. 



PREVENTION AND REMEDIES. 



With regard to this serious pest, we have tried many things. At 

 first fumigation, with hydrocyanic-acid gas, was considered useful, but 

 later it was found to only be partially successful, and that as the mite 

 increased so rapidly it was of little use. Moreover the gas does 

 not affect any mites in the ground, and if there is any moisture on the 

 buds it affects the mite scarcely at all. In fact, even for cuttings and 

 young stock, it is of little value. I believe hydrocyanic-acid gas is 

 valueless for all acari. A new method of fumigation is being tried by 

 Mr. Wilcocks of the S. E. Agricultural College, which so far seems 

 successful. Should it prove so I shall at once forward the results. 



