PROC. ENT. SOC. WASH., VOL. 20, XO. 7, OCT., 1918 151 



they happen to concentrate on a single tree or group of trees. 

 Where trees are not numerous nor large there is less chance for 

 concealment. 



Last July, 1917, while investigating grasshopper conditions in 

 western North Dakota, the writer visited one farm where a 

 limited windbreak of small box elder trees had been planted 

 not far from the house. The owner complained of the big worms 

 he had picked from these trees, "by the pailful" he said, in order 

 to scald them to death with boiling water. In the winter he 

 had gathered and destroyed cocoons in large numbers. A short 

 search disclosed several Cecropia moths hiding among the leaf 

 clusters. Eggs were easily found on the leaves near by while 

 numerous empty cocoons on the twigs witnessed to the past 

 history of the insect in the grove. These trees had been more or 

 less injured for several years past according to the farmer's story. 



A few weeks later, in September, 1917, in the city of Dickinson, 

 North Dakota, a place of less than 4000 inhabitants, I was in- 

 formed that for two or three years the citizens had been waging 

 war on this same moth. Some one or more of the Women's 

 Clubs had awakened to the danger that threatened the trees of 

 the city by reason of the attacks of great numbers of the Cecropia 

 larvae and had come to the rescue by offering, at the outset, a 

 cent each for the cocoons that were brought in. 



The sharp-eyed boy mobilized at once and two years ago 

 thousands of cocoons were gathered and destroyed. The dis- 

 covery was made however by the committee of destruction that 

 many of these cocoons contained only dead inmates, the worms 

 having died after spinning the case, before pupation. Quite a 

 percentage of the larvae were also victims of parasites and it 

 was clearly poor policy to kill the enemies of these pests. Con- 

 sequently last year it became the unpleasant duty of the mem- 

 bers of the 'committee to snip off the end of each cocoon to ascer- 

 tain the condition of the interior and so to eliminate the dead 

 ones from the payroll. This greatly increased the labor of the 

 undertaking but it saved money. 



The financial burden of the battle became finally so onerous 

 that the market price for cocoons sagged to half a cent apiece, 

 but even at this small figure the boys made good money and the 

 treasurer paid out nearly one hundred dollars during the winter 

 of 1916-1917. A little computation gives one the remarkable 

 figure of nearly 20,000 cocoons destroyed in a single year in 

 spite of previous campaigns that were apparently drastic in their 

 thoroughness. 



The fight is still on in Dickinson and the small boys, and small 

 girls as well, were in October, 1917, already beginning to collect 

 and store their prizes for redemption when the usual offer for 

 cocoons was again made public. 



