INSECT PESTS 85 



insecticides cannot be stated, but those who wish to 

 make up their own wash with a known nicotine content 

 might try the following formula, varying it from time 

 to time to find the minimum percentage of nicotine 

 which is effective : 



Nicotine 98 per cent. . 3 oz. 



Soft soap . 2 lb.~4 Ib. (latter 



if water is some- 

 what hard). 



Water . . .40 gallons. 



The number of times which it is necessary to spray 

 is also variable ; sometimes as many as three applica- 

 tions are made as a regular routine, but it is probable 

 that if the willows are well sprayed in late May or 

 early June it will seldom be necessary to -spray again 

 the same year. 



Apart from spraying which will deal with aphides, 

 leaf-eating grubs and beetles, and to a less extent with 

 the moth caterpillars which live in the shoots, no other 

 direct measures for control can be recommended for 

 actual experience. On the Continent the leaf-eating 

 willow beetles are caught by various forms of apparatus 

 by means of which the insects are shaken off into trays, 

 and some such method might be of service in this 

 country in the case of the Willow Weevil (Cryptor- 

 rhynchus la pat hi) , against which sprays are useless. No 

 control measures are known in the case of the midges 

 causing button top or in those of the various insects 

 which burrow in the stumps or rods. In button top, 

 however, assuming that the insects pass the winter 

 in the buttons, and remembering that affected rods 

 are usually of little value, it seems regrettable that 

 such rods should be left about in the neighbourhood 



