68 



THE BROWN-TAIL MOTH. 



poses a large number of pear trees, from ten to fifteen feet 

 high, standing on an estate in the southern part of Maiden. 

 These trees were tlioroughly and (juitc uniformly infested 

 ■with the brown-tail moth, and the caterpillars had emerged 

 and commenced feeding, being at the time of the experi- 

 ments in the second and third molts. In each case these 

 trees were sprayed with various insecticides, as given below. 

 Ill the case of arsenate of lead, the (juantities mentioned 

 represent the actual dry arsenate of lead contained in the 



ingredients used. 



Field Experiments* 



1. Arsenate of lead, 1 pound to 150 jiallons of water: — 



May 19, 

 May 20, 

 May 21, 

 May 22, 

 May 23, 

 May 24, 

 May 25, 

 Mav 26, 



sprayed, 

 no results. 

 no results, 

 ceased feeding. 

 50 per cent. dead. 



May 27, 

 May 28, 

 May 29, 

 May 30, 

 May 31, 

 June 1, 

 June 2, 



90 per cent. dead. 



all dead. 



2. Arsenate of lead, 2 pounds to 150 gallons of water : — 



May 19, 



May 20, 

 May 21, 

 May 22, 

 May 2.i, 

 May 2-1, 

 .May 25, 

 Mav 20, 



sprayed, 

 no results. 

 no results. 

 ceased feeding. 

 50 per cent. dead. 



May 27, 

 ]\Iay 2S, 

 May 29, 

 May 30, 

 May 31, 

 June 1, 

 June 2, 



90 per cent. dead. 



all dead. 



3. Arsenate of lead, 5 pounds to 150 gallons of water: 



May 19, 

 May 20, 

 .Mav 21, 

 May 22, 

 May 23, 

 May 24, 



sprayed, 

 no results, 

 no results, 

 ceased feeding. 

 KO per cent. dead. 



IMay 25, 

 May 26, 

 May 27, 

 May 28, 

 May 29, 



all dead. 



4. Arsenate of lead, 10 pounds to 150 gallons of water: — 



• Olio pound arsenate of lead as used in these experiments is equal to about 

 two pounds commercial arsenate of lead paste. 



