16 BULLETIN 621, U. S. DEPARTMENT OF AGRICULTURE. 



beetles of the genus Aphodius^ so abundant in spring and fall. The 

 function, of most of these beetles is that of scavengers, though one 

 species, A. granarius, has been known to feed on and injure corn. A 

 crow collected in California in February had eaten 50 of these. In 

 view of their abundance, it is not surprising that upward of a score 

 of these small beetles were frequently found in single stomachs. 

 Members of the genus Atcenius, which live in rich earth, appeared less 

 frequently than Aphodius. Tumblebugs (Canthdrb and Geotrupes) 

 often form a considerable portion of the stomach contents, and asso- 

 ciated with them frequently are the remains of other scavengers, 

 Coprls, Onthophagus, or the brilliantly colored Phanwus carhifex. 

 While it can not be said that the crow is aiding man by consuming the 

 scavenger scarabseids, unless it be in case of some species possessing 

 herbivorous habits, as Aphodius granarius, it is doubtful whether it 

 is doing serious harm. Feeding on these beetles may well be consid- 

 ered to have a neutral effect. 



Carabids (ground beetles). — Only recently has anything like a 

 fair value of predacious beetles been recognized, and economic en- 

 tomologists are depending more and more on them in battling with 

 insect pests. A most striking example of the effective work of 

 predacious carabids is found in the activities of the larva of the im- 

 ported Galosoma sycophanta, a foe of the gipsy moth in New Eng- 

 land. When it is considered that carabid beetles, including members 

 of such a highly beneficial genus as Calosomct; are frequently eaten 

 by crows, a study of this portion of the food becomes of the utmost 

 importance. It must be borne in mind, however, that certain ground 

 beetles, as Agonoderus palUpes and a few members of the genera 

 Arnara and Anisodactylus, to some extent are herbivorous and have 

 been known to do appreciable damage. 



Ground beetles constituted 1.56 per cent of the yearly food of the 

 adult crows examined, the bulk of these insects being taken in the 

 months from April to September. May, with 5.54 per cent, was the 

 month of greatest consumption, and June, with 3.24, stands next. 

 In the fall and winter months these beetles did not form so much 

 as 1 per cent of the food. Reference to the tabulation on page 43 

 will show that the monthly percentages of these insects eaten well 

 represent their relative abundance at different seasons of the year. 

 While fragments of carabids were found in a great number of stom- 

 achs, only rarely did they occur in numbers or constitute a large pro- 

 portion of the food, the exceptional stomachs coming mainly from the 

 West, where many of the smaller and apparently herbivorous species 

 are extremely common. 



The caterpillar hunters (Caloso?na spp.) are probably the most 

 conspicuous and valuable carabids eaten by the crow. Both adults 



