EOSEBREAST VS. POTATO BEETLE. 



47 



There remains for consideration the family of beetles which con- 

 tributes most largely to the grosbeak's subsistence, namely, the leaf- 

 beetles (Chrysomelida^). This family, as an item of food of the 

 rosebreast, is not only most important among beetles, but is only 

 second among both animal and vegetable items. In it are included 

 a number of pests preyed upon by the bird, such as the striped and 

 spotted cucumber beetles, 'the strawberry rootworm, the plum leaf- 

 beetle, the locust leaf-miner, and in addition that pest which figures 

 so largely in any discussion of the economic value of the rose-breasted 

 grosbeak, the notorious Colorado potato beetle (fig. 25). 



The original home of this insect was in Mexico and the Rocky 

 Mountains, where it fed upon the sand-bur {Solanum rostrati/m), 

 a plant closely related to the potato. Finding a new and abundant 

 supply of food in the cultivated potato, the beetle immediately began 

 to multiply and to migrate eastAvard, spreading from 1830 to 1874 

 over the northern half of the eastern United States. As it encount- 

 ered practically no enemies in its new home it became so abundant and 

 inflicted so great damage that successful cultivation of potatoes seemed 

 no longer possible. 

 However, just as the 

 beetle found a new 

 food, so it in turn be- 

 came new food to a 

 numl)er of mammals, 

 birds, and insects, and 

 presenth^ the farmers fiq. 2 

 learned to destroy it 

 in large numbers with poisons. Hence it is no longer greatly 

 dreaded, though in most sectiojis constant vigilance must be exercised 

 to prevent it from ruining the crop. 



Naturally during the period when the beetle was doing most dam- 

 age everyone was on the lookout for means of checking its increase, 

 and the discovery of each new natural enemy was heralded far and 

 wide. Attracting most notice among these was the rose-breasted gros- 

 beak, and many articles Avere written calling attention to the newly 

 discovered trait of this beautiful bird. It should be noted also that 

 several other birds, including the bobwhite, prairie chicken, sharp- 

 tailed and ruffed grouse, red-tailed hawk, nighthawk, cuckoo, crow, 

 Englisli sjjarrow, cardinal, scarlet tanager, wood, hermit, and olive- 

 backed thrushes, and robin, eat potato beetles occasionally. 



The grosbeak's habit of feeding on the potato beetle was noted 



almost sinudtaneously in many localities, and references are at hand 



for the States of Missouri, Iowa, Minnesota, AVisconsin, Illinois, 



Michigan, and Ohio. The rosebreast actually exterminated the po- 



18848— Bull. 32—08 — 



a o 



o. — I'otato beetle (Lcptinotarsa decemlineata) . 

 (From Chitteticlen. Bureau of Entomology.) 



