46 THE KELATION OF SPARROWS TO AGRICULTUIiE. 



replaced on oak leaves, with which they blended perfectly, and offered 

 to the birds. All three sparrows immediately pounced upon the grass- 

 hoppers and greedilj' devoured them. A dozen experiments were tried 

 with the song sparrow to test the efficacy of the protective colora- 

 tion of weevils. A weevil {Sitones hispidulus) sunk almost beneath 

 sand of its own color was always instantly spied out. The results of 

 these experiments, together with the fact that protectively colored 

 weevils and grasshoppers form an imi3ortant part of the contents of 

 stomachs examined, indicates that sparrows are not baffled by such 

 devices. 



Protection by means of the ejection of an offensive fluid seems to 

 be more effective. Blister-beetles {Epicauta), which possess an irri- 

 tating secretion, were repeatedly refused by the three sparrows. 

 Disagreeable secretions when coupled with showy or warning colora- 

 tion were found, in a number of cases, to repel the attacks of the 

 sparrows. A gaudj' orange and black harlequin cabbage bug {Mur- 

 gantia liistrionica) was offered to the birds. The junco and song 

 sparrow refused it, but the white-throated sparrow seized it and after 

 some preliminary pecking ate it piecemeal. Two other injurious 

 insects, the three-lined flea beetle {Lema trilineata) and the twelve- 

 spotted cucumber beetle (Diahroiica 12-punctata) ^ which are warn- 

 ingly colored beetles with pungent secretions, were placed in the cage, 

 but the sparrows, though exceedingly hungry, refused them. Tlie 

 failure of the birds to destroy these pests is in part offset by tlie fact 

 that they do not prey on the useful ladybird beetles of the family 

 Coccinellidpe, which are also both warningly colored and ill flavored. 

 Two species of these insects {Adalia hipunctata and Hippodamia 

 maculata) were offered to the birds a dozen times, but were always 

 allowed to crawl out of the cage unmolested. The results of these 

 experiments coincided with the data accruing from the examination 

 of the contents of stomachs in the laboratory. 



The frequency with which the smaller and less useful foruis of 

 ground-beetles (Carabidpe) are met with in examination of sparrow 

 stomachs suggested the carrying out of some exj)eriments with these 

 insects. ^. Carabidje emit volatile irritating fluids which would natu- 

 rally be -expected to render them immune from the attacks of birds. 

 Just how effective this protective device actualh^ is will appear from 

 the account of these experiments. 



Two specimens of Amara impuncticollis, a carabid about'one-third 

 of an inch long, were placed in the cage wherein were the three spar- 

 roAYs. The white-throated sparrow instanth^ seized one of these 

 beetles and the song sparrow the other, while the junco was obliged 

 to content itself with pieces dropped by its mates as they hurriedly 

 ate the tidbits. Before any further test could be made the junco 

 and white-throated sparrows were, unfortunateh', accidentall}^ killed; 

 the series of experiments was continued, however, with the song 



