NATURAL ENEMIES 



Fortunately this insect is attacked by a number of parasites 

 that help greatly in checking its increase. A careful study of 

 the infested elms in Manchester, made by the writer in August, 

 showed that at least ten per cent, of the caterpillars had been 

 killed by parasites. This is a hopeful sign for the future, for 

 it shows that if the people will do their part in cleaning oft' the 

 egg cases, the parasites will help to destroy those that escape. 

 But the parasites are not sufficiently numerous for the public 

 to leave the work entirely to them. 



REMEDIES 



The simplest and most effectual method of checking the 

 injury of this insect is to pick oft' and destroy the egg masses 

 during autumn, winter, or spring. There is a long period in 

 which the insect is open to attack by this method ; and if the 

 owners of trees generally would employ it, there would be lit- 

 tle trouble from the pest. In New Hampshire it appears 

 advisable not to collect the egg masses until Octobei or 

 November, in order to permit the useful parasites to mature 

 and escape. It is a simple matter to collect the egg masses on 

 the lower portions of the trunks, but higher up and on the 

 larger branches they are more difficult to reach. But by means 

 of ladders, or climbing irons, or agile boys, the difficulty may 

 be overcome. After the masses are collected, they may readily 

 be burned. 



At the time indicated it is necessary to collect only those 

 cocoons which have egg masses upon them. Other cocoons 

 are empty or contain parasites. 



These insects may also be destroyed by spraying the trees 

 early in summer, after the caterpillars have hatched, with 

 Paris green in water, at the rate of four or five ounces of poison 

 to fifty gallons of water. Directions for spraying have been 

 given in previous publications of this station. For shade trees 

 attacked only by Tussock caterpillars, the method of collect- 

 ing the eggs is believed to be preferable to spraying. 



