Insects, etc., Injurious to the Gooseberry. 



281 



their increase, their equally sudden disappearance, even in warm 

 weather, are subjects about which much further investigation is 

 necessary. 



PKEVENTION AND TREATMENT. 

 The recognised treatment for the Eed Spiders has been some form 



of sulphur wash. Liver of sulphur has proved the most convenient 



form. It has, however, been found of no 



avail in certain years. For instance, in 1907, 



little good was done by spraying with this 



acaricide. The other acaricide found to work 



when sulphur fails is paraffin emulsion, and 



the best results have been obtained with 



paraffin jelly. Considerable success has also 



attended the use of nicotine washes, which 



I found by far the most successful of all in 



1907. 



The question of preventing the attack 



is one which growers naturally are most 



concerned with. 



We know that the immature acari 

 shelter in the 

 crevices, etc., of 

 the wood in Feb- 

 ruary and March, 

 and at this time 

 a heavy spraying 



would be sure to kill very many. Mr. John 

 Eiley of Putley Court, Ledbury, wrote me 

 in 1902 that he had found great benefit from 

 spraying with caustic alkali wash, and it is 

 quite possible that this treatment in late 

 winter kills the young acari. 



Washing, in any case, in late February 

 cannot fail to kill large numbers, and then 

 fairly strong paraffin emulsion may be used ; 

 up to as much as five gallons of paraffin to 

 100 gallons of wash has been found to do 

 no harm. 



Where attack only makes itself notice- 

 able in April or May then we must spray with either the liver of 



sulphur or the paraffin jelly, and it may be pointed out that to be of 



FIG. 192. GOOSEBERRY RED SPIDER 

 AND OVA. 



(Greatly enlarged.) 



FIG. 193. EMPTY EGG-SHELLS OF 

 RED SPIDER. 



(Greatly enlarged.) 



