14 



FOOD HABITS OF THE GROSBEAKS. 



The last-named group includes two mainly beneficial families, the 

 ground beetles (Carabidae) and the fireflies (Lampyridae). Since the 

 destruction of these beetles by the cardinal tends to neutralize the 

 good done in other ways, it is important to understand thoroughly 

 the nature of the bird's relation to them. Among the most beneficial 

 of beetles are the caterpillar hunters {Calosoma^ fig. 7), which 

 ascend trees in quest of their prey, a rare habit among ground beetles. 

 Thus these beetles attack caterpillars in a way others are unable to 

 do. Two cardinals ate beetles of this genus. Another large carabid 

 {Pasitnachxis) ^ an enemy of grasshoppers and the army worm, was 

 eaten by one redbird. Others devoured include Harpalus caliginosus^ 

 which is the bulky black beetle often seen feeding on the flowers of 

 ragAveed and Avhich is evidently not entirely predaceous, and a 

 larva of the nearly related beetle Dicaelus. Three birds captured 

 individuals of the medium-sized but very hard Scarites suhterraneus^ 

 which generally hides under stones by day. Specimens of two species 



of Anisodaet/i/li/s and one beautiful blue 

 ('nllhia also were eaten. In all 34 red- 

 birds fed upon beetles of this useful 

 family, but each must have eaten spar- 

 ingly, for the beetles compose but 0.75 

 percent of the entire food, an amount 

 too small to be reckoned against the con- 

 sumer of more than 8 times that quantity 

 of grasshoppers, in addition to many 

 other injurious insects. 



Fireflies were eaten by only 4 cardi- 

 nals, one of the birds obtaining the com- 

 mon black and yellow soldier beetle 

 {('JiauUognathnfi marginatus)^ which 

 commonly feeds on the pollen of midsummer blossoms, and another, 

 one of the small black fireflies {Telej)hori(s pusiUu.s) , the larva.^ of 

 which are enemies of some common agricultural pests. Fireflies are 

 eaten in such moderate measure that it is impracticable to assign 

 them a percent, and we may conclude, so far as the present data go, 

 that the cardinal does no ai^preciable injury to this group of insects. 

 The wasps and similar insects (Hymenoptera) include among their 

 number many beneficial parasitic species, and for that reason their 

 status as food of the redbird must be looked into. Fifty-nine of the 

 grosbeaks examined had eaten these insects, but they amount to only 

 0.92 percent of the total food. None were positively identified as 

 parasitic species, while some injurious forms were distinguished. 

 Eleven cardinals ate ants, including the harvesting ants {Pogono- 

 myrmex) and the small reddish Lasius, which foster plant lice, nota- 

 bly the corn root aphids. One grosbeak ate a sawfly, which also is an 

 insect of unsavory reputation. 



Fig. 7 — Caterpillar 

 soma scrutator). 



hunter ( C'aJo- 

 (From Riley.) 



