36 



THE CANKER-WORM 



Forbush ' show that the chickadee, or black-capped titmouse, 

 devours the eggs throughout the winter, and the moths when 

 they are present. '• Mr. Bailey is very positive that each 

 chickadee will devour on the average thirty female canker- 

 worm moths per day from the twentieth of March until the 

 fifteenth of April, provided these insects are plentiful. If the 

 average number of eggs laid by each female is 185, one chicka- 

 dee would thus destroy in one day, 5,550 eggs; and in the 

 twentv-five days in which the canker-worm moths crawl up 

 the trees, 138,750. It may be thought that this computation 

 is excessive, and it is probable that some of the moths were 

 not captured until they had laid some of their eggs, but the 



Fig. 3. — The fall canker-worm; a, egg mass, natural size; />, egg, magni- 

 fied; c, larva; d, pupa; e, female moth; f, male moth. (After Riley.) 



chickadees are also busy eating these eggs. When we con- 

 sider further that forty-one of these insects, distended as thev 

 were with eggs, were found at one time in the stomach of 

 one chickadee, and that the digestion of the bird is so rapid 

 that its stomach was probably filled several times daily, the 

 estimate made by Mr. Bailey seems a very conservative one. 

 He now regards the chickadee as the best friend the farmer 

 has, for the reason that it is with him all the year, and there is 

 no bird that compares with it in destroying the female moths 



1 Mass. Crop Report, July, 1895. 



