14 



METHODS OF COMBATING. 



The principal methods employed by the willow- growers of this 

 State in combating the cottonwood leaf-beatle may be classified 

 under two heads : 



(i) The application of poison or repellents to the willows , either 

 dry or mixed with water. — The poisons most commonly used are 

 Paris green and London purple, applied either in water or mixed 

 with lime or land plaster. Paris green and land plaster, about 

 I part of the poison to 40 parts of land plaster, is considered an 

 effectual remedy if applied when the willows are wet with dew 

 or rain. A solution of copper sulphate without lime, i pound to 

 from 7 to 12 gallons of water has been tried by several growers 

 about Liverpool, one of the willow -growing centres near Syracuse, 

 but without much success. If applied strong enough to materi- 

 ally check the insect, it injures the willows. 



None of the above compounds have proven uniformly satisfac- 

 tory in the hands of the willow-growers. 



(2) By usivg machines for catching the beetles. — These 

 machines are made for use with either horse or hand power. 

 The two forms are illustrated at Plates IV, V and VI which are 

 from photographs taken by Mr. Rogers of Liverpool, at the 

 writer's request. The dimensions of the body of the horse-power 

 machines are as follows : Length 5 ft., width of rear end 2 ft., 

 front end i ft. 8 in., depth 6 in. The body thus forms a shallow 

 tank which may be lined with zinc or tin and in which kerosene 

 oil or kerosene oil and water, the oil forming a thin film on the 

 surface of the water, should be kept while the machine is in use. 

 A number of narrow strips are placed longitudinally over the top 

 in the manner shown in Plate IV to keep the willows from touch- 

 ing the oil. Two stout runners fastened to the under side support 

 the tanks. Plate V shows the machine in position ready for 

 use. As will be observed, it is made to run between the rows ; 

 the loag arms which extend obliquely from either side, cause the 

 willows to bend over as the machine moves along and at the same 

 time rub off the beetles and many of the larvae and pupse which 

 drop into the tank and are quickly killed by the oil. A lighter 

 machine for hand power is shown at Plsite VI. 



