THE BROWN-TAIL MOTH 



129 



useful by those making a business of collecting the webs. 

 All webs should be removed by April 1. 



The question is often asked, "Will it pay me to clean 

 the webs from my own trees if my neighbor does not?" 

 A glance at figure 20 will answer this better than argument. 

 From the habits of the pest it is apparent that but little 

 spread takes place except by the winged moths in late sum- 



FiG. 20. — Pesir tree defoliated by the caterpillars of the Brown-Tail Moth. The webs 

 on the trees in the background were destroyed the previous winter. Photograph 

 taken at Vine Street, Somerville, Mass., May 27, 1897. (After Fernald and Eirkland.) 



mer. If the caterpillars are so abundant as to spread from 

 neighboring property they may be prevented by sticky 

 bands on the iminfested trees as described below. 



Spraying. — ^While the caterpillars are young they may be 

 effectively destroyed by spraying with arsenate of lead. 

 The brown-tail caterpillars seem to be much more suscep- 

 tible to the poison than those of the gypsy moth. Experi- 

 ments made by us during the past season in the laboratory 

 indicate that if sprayed while the caterpillars are young 

 early in May that arsenate of lead at the rate of three 

 pounds per barrel of water should be sufficient, but if de- 

 layed until late in May or June 1, when they are nearly 

 full grown, five pounds per barrel should be used. More 



