20 MAINE AGRICULTURAI, EXPERIMENT STATION. 



temperature or other climatic conditions which have an effect 

 on the development of the caterpillars. 



Four pounds of lead arsenate paste to fifty gallons of water 

 can be used at this time with safety on trees with winter fruit. 

 For trees with very early fruit it would probably be better to 

 use not more than two or three pounds. If dry arsenate of 

 lead is used half the above amounts to fifty gallons of water is 

 sufficient. 



In August when the newly hatched caterpillars are young 

 they can readily be killed as they are at this time especially sus- 

 ceptible to the poison. For the past two years the browntail 

 caterpillars have fed late into the fall, many becoming half 

 grown and working about the fruits as well as the leaves. This 

 experience leads us to emphasize the need of an August spray 

 for this pest. While the species normally forms its winter 

 nest while tiny and before it has fed more than a few weeks this 

 habit has many exceptions and the late feeding on trees in fruit 

 is a serious menace on account of the poisonous hairs shed by 

 the caterpillars. It is less satisfactory to spray in the spring as 

 the caterpillars if numerous eat the tender leaves as fast as they 

 unfold. Then, too, the leaves are constantly expanding in the 

 spring, and fresh unpoisoned leaf surface is exposed soon after 

 a spray has been applied. Thus one August spray will do what 

 it would take several applications to accomplish in the spring. 



The other five species to guard against in this way are the 

 red-humped caterpillar, yellow-necked caterpillar, fall web 

 worm, hickory tiger moth and spotted tiger moth. 



