10 REPORT ON INJURIOUS INSECTS FOR 1907. 



REPORT ON EXPERIMENTS 

 WITH THE BLACK-CURRANT GALL-MITE. 



Eriophyes ribis (Nalepa). 



The experiments on the Black-Currant Gall-Mite, Eriophyes ribis 

 (Nalepa), were commenced by me in the early part of 1899. After a 

 thorough investigation of the life history and habits of the mite (I) atten- 

 tion was devoted to providing a remedy. 



Various experiments were made with different arsenical fluids, 

 bruised hellebore, lime, sulphur and lime, etc., and whilst many 

 considerably reduced the numbers of mites, none were found to be of 

 any practical value. 



In 1901, some bushes badly infested with the mite were treated 

 twice a week during the migration season with a sprayfluid consisting 

 of: 



Sulphur ... ... ... ... 2 Ibs. 



Soft Soap ... ... ... ... 25 Ibs. 



Water ... ... ... ... 50 gallons. 



Made as follows : The sulphur was mixed with water to a gruel ; 

 the soft soap was mixed with 5 gallons of boiling water, and then the 

 two mixtures were added together and well mixed, water being added 

 to make 50 gallons. The results obtained from the use of this mixture 

 were very encouraging, but it was soon evident that it could not be 

 applied by the fruit-grower at a cost which would repay him for the 

 extra labour involved. The two main objections were, firstly, the large 

 number of applications which were given in my experiments, and, 

 secondly, the large quantity of soap used. But these experiments 

 very clearly indicated that the mite could be destroyed to a large extent 

 by the use of sulphur, and it but remained to be demonstrated in what 

 form and proportions it could best be applied, and whether the number 

 of applications could be reduced. 



In 1905 a further series of experiments were commenced on very 

 badly infected Black Naples, Baldwins, and Boskoop Giants. These 

 were as follows : 



Three rows of bushes were dusted with equal parts of ground 

 unslaked lime and flowers of sulphur. Three rows were sprayed with 

 a mixture consisting of i Ib. lime, i Ib. sulphur, and 20 gallons of water ; 

 whilst a single row was sprayed with a mixture consisting of i Ib. 

 sulphur, i Ib. soft soap, and 20 gallons of water. 



In the dusting operations one row was dusted once, one twice, and 

 one three times. 



(i) Report on Economic Zoology, No. i, 1004. 



