The Crow in Its Relation to Agriculture. 







nearly one-fifth of the crow's food. Caterpillars form about 1.5 per 

 cent of the diet of the adults; nestlings, however, eat nearly four 

 times as much. Other insects, as bees, wasps, ants, flies, and true 

 bugs, are taken in only small quantities, and the economic problems 

 involved are not important. 



The numbers of the various insects eaten during different months of 

 the year are often indicative of their period of abundance. Early in 

 spring, for instance, few May beetles or other scarabseid beetles are 

 eaten; but, beginning in April, they form about 5 per cent of the 

 crow's food, and in May the presence of the annual crop of May 

 beetles is indicated by the extraordinary percentage of 20.99. Like- 

 wise the monthly increase of grasshoppers from May to September 

 is shown in the crow's diet by the approximate percentages of 4, 6, 14, 

 19. and 19, representing the proportion of these in the food taken. 

 The height of the caterpillar season also is indicated by the ap- 

 proximate percentages of 1, 3, 6, and 2, for the months of April, May, 

 June, and July, respectively. 



TABLE I. Monthly percentages of the principal food items of the adult crow. 



The size and the voracious appetites of crows make these birds 

 especially valuable in times of outbreak of one or another of the insect 

 pests upon which they feed. In the stomach of a crow collected in 

 April were the remains of 85 May beetles, and these formed less than 

 half the food; in another were 72 wireworms; and in a third were 

 fragments of 123 grasshoppers. Twelve birds in a series collected in 

 Manitoba had fed on grasshoppers at the average rate of 57 each, 

 and one crow secured in Michigan had eaten 483 small caterpillars. 

 Nestling crows, whose rapidly growing bodies require even greater 

 quantities of insect food than the adults, often excel their parents in 

 the good work of insect destruction. One brood of 4 had consumed 

 418 grasshoppers, and another brood of 7 had made away with 585 

 during a few hours before they were collected. Of a total of 157 

 nestling crows secured in Kansas in 1913, 151 had been fed on grass- 

 hoppers. Caterpillars, always a favorite source of food for nestling 

 172161 20 2 



