82 BULLETIN" 621, U. S. DEPAKTMENT OF AGRICULTURE. 



the most destructive pests are at their lowest ebb. A little later, 

 nestling crows appear on the scene, outnumbering their parents two 

 to one, and assist in the work of destruction. Not only do the young 

 birds eat a much larger proportion of insect food than do their 

 parents at the same time of year, but the quantity of food required 

 to develop their rapidly growing bodies is considerably greater. 

 That injurious insects greatly outnumber beneficial insects in the 

 diet of the crow will be seen from the following review of the four 

 most important orders: 



Beetles. — The crow's relation to beetles is all that the frugal agri- 

 culturist could desire. Foremost among these insects in its food are 

 May beetles and their destructive larvae, white grubs. These, with a 

 few other phytophagous scarabseids and scavengers of the same 

 family, as disclosed by stomach examination, totaled over half the 

 beetles eaten. The destruction of a few click beetles, weevils, and 

 wood-boring beetles also must be considered in the bird's favor. 

 Ground beetles ; most of which are beneficial, made up about a fifth 

 of the beetle food and must be charged against the crow. Copropha- 

 gous and necrophagous forms eaten, as Silphidee and Staphyiinidse, 

 are slightly beneficial. 



Grasshoppers. — In its consumption of grasshoppers the crow ren- 

 ders man its most important service. In regions where these de- 

 cidedly injurious insects are abundant their nymphs form the prin- 

 cipal insect-food of nestlings. Not only do the food habits of these 

 young birds exert a strong control on the increase of grasshoppers, 

 but the destruction of these insects is accomplished so early in the 

 season that it has the added effect of preventing much of the damage 

 which would be inflicted if the work were delayed till later in the 

 year. 



Caterpillars. — In its consumption of caterpillars the nestling crow 

 exceeds its parent in effectiveness in the ratio of about -A to 1. This 

 food, found in over a third of the stomachs of young crows, is all 

 in the bird's favor, especially since cutworms constitute the major 

 portion. 



True bugs. — Among the true bugs, only soldier bugs (Penta- 

 tomidee) and the periodical cicada are worthy of mention in this 

 summary. The former, taken in small quantities on numerous occa- 

 sions, embrace both predacious and herbivorous species^ an indis- 

 criminate destruction of which must be largely neutral in effect. The 

 destruction of the periodical cicada must also be considered of minor 

 economic importance. 



Spideks. 



The exact economic status of the large wolf spiders (Lycosidse), 

 which comprise the major part of the arachnid food of young crows, 



