130 THE FOREST TENT CATERPILLAR 



destroyed by use of a stiff broom or by various other methods^ 

 The earlier this is done after the larvae are all hatched the less 

 will be the injury to the foliage. 



The masses of caterpillars below the bands are sometimes 

 killed by pouring on kerosene. If this method is employed, 

 great care should be taken not to add enough to saturate the 

 bark. Many trees have been killed by carelessness in such 

 use of kerosene. 



Collecting cocoons. — A large proportion of the cocoons are 

 commonly spun where they can be reached. The destruction 

 of these will lessen the number of moths that lay eggs for the 

 next season's brood of caterpillars, although it will also lead 

 to the destruction of large numbers of parasites. 



This collecting of the cocoons has been done extensively in 

 certain towns. In Hanover and Claremont the selectmen 

 offered a reward of five cents per hundred cocoons, and in 

 the former town 80,000 cocoons were collected and destroyed. 

 The poster gotten out by the Claremont authorities is repro- 

 duced on the opposite page. 



The chief objection to this method is that it leads to the 

 destruction of large numbers of parasites. The proportion of 

 parasites to moths is likely to vary considerably in different 

 localities. Our observations indicate that at Claremont, last 

 season (1899), about 30 per cent, of the pupa^ were para- 

 sitized, while at Brandon, Vt., more than 40 per cent, were 

 parasitized. Now these parasites are Nature's means of 

 checking the outbreaks of this Forest Caterpillar, and it seems 

 unfortunate that in destroying our foes we should also destroy 

 our friends. It must be borne in mind, however, that any 

 parasite found in these cocoons will not take effect upon next 

 year's brood of caterpillars until they have completed their 

 growth and done the damage, so that as regards the next sea- 

 son alone it is better to destroy the pupae, even if some of the 

 parasites are destroyed at the same time. 



A simple method, however, may be adopted by which the 

 moths may be destroyed and most of the parasites saved to 

 continue their good work. It was first suggested to me by 

 Mr. Fiske. Select a piece of shaded grassland, which is not 



