46 



FOOD HABTTS OF THE GROSBEAKS. 



three of these destructive weevils, Avhich may be taken as indicating 

 that an opportunity to feed on them is not overlooked. In this con- 

 nection it is of interest to recall the other birds that are known to 

 prey upon this pest. They are 8 in number : Great-crested flycatcher, 

 Baltimore and orchard orioles, yellow-throated vireo, bank swallow, 

 veery, hermit thrush, and bluebird. The grosbeak does not confine 

 itself to the plum curculio, but evinces a taste- for related species, 

 two of which were identified. These infest the hackberry and hick- 

 or}^, respectively. A fourth kind was present in the stomachs, but 

 could not be assigned a specific name. The curculios destroy a large 

 proportion of the fruit of the trees they attack, and are capable of 

 doing vast damage ; hence the services of the birds that devour them 

 are of great value. 



Belated to the curculios are the nut weevils (Balaninus), which 

 attack their favorite plants in much the same way, and often ruin 



the crop of nut-bearing 

 trees. Six grosbeaks ate 

 from 1 to 3 each of these 

 weevils, one bird captur- 

 ing 2 acorn weevils (B. 

 nasicus). Another cur- 

 culionid (H ylobius 

 pales), which feeds both 

 in living pine trees and 

 pine logs, is included in 

 the grosbeak's diet, and 

 a weevil (Ampeloglypter 

 sesostris), which infests 

 the Virginia creeper, was highly relished by an Illinois rosebreast, 

 11 being eaten, which constituted 74 percent of the stomach contents. 

 Others in the same group are consumed, as many as 4 or 5 being eaten 

 by individuals of the more than 20 birds which fed upon them. 



A second family of weevils, the scarred snout-beetles, also con- 

 tributes to the fare of this grosbeak, and four of them composed 87 

 percent of the food of one bird ; while another rosebreast, one of four 

 which fed upon clover weevils (Sitones), captured 13. Billbugs 

 (Calandridse) are represented in the bird's diet by the conspicuously 

 red and black colored snout-beetle (Rhodobaenus 13-punctatus) , com- 

 mon on thorough wort {Eupatorium) . A weevil of yet another branch 

 of the suborder is sometimes devoured, namely, the peculiar brenthid 

 (Eupsalis minuta) , a very slender weevil which bores into living oak. 

 Altogether weevils constitute 3.64 per cent of the rosebreast's food, in 

 which amount are included several great pests; hence the bird's 

 weevil-eating propensities result in much benefit to man. 



Fig. 24.— Plum curculio (Conotrachelus nenuphar). 

 (From Chittenden, Bureau of Entomology.) 



