INSECT FOOD OF THE BLUE GROSBEAK. 83 



Injurious beetles comprise 24.4 percent of the grosbeak's food, 

 almost half (11.25 percent) of which amount consists of members of 

 the May beetle family (Scarabseida?). Adult June bugs, and their 

 larvae, the white grubs, were devoured by some birds to the exclusion 

 of other food, and 1 grosbeak had eaten 3 of the common dung- 

 beetles (Aphodius fimetarius). Weevils are next in importance 

 among beetles, and 7.18 percent of the bird's seasonal food was made 

 up of these pests. Many of them were scarred snout-beetles (Otio- 

 rhynchidse) and curculios (Curculionidse) ; some of them certainly 

 were injurious species. Two grosbeaks selected the conspicuously 

 red and black colored billbug (Rhodobmnus 13-punctatus). each 

 eating 2. Leaf -beetles (Chrysomelidse), wood-borers (Buprestidse), 

 click-beetles (Elateridse), and long-horned beetles (Cerambycida?), 

 nearly all of which are injurious, were also devoured. 



The most important element of the animal food, however, is grass- 

 hoppers. Crickets and long and short horned grasshoppers are 

 eagerly consumed, composing 27.2 percent of the total food. Thirty- 

 two of the 51 

 blue grosbeaks 

 ate them, several 

 taking nothing 

 else. They are fed 

 to the nestlings 



in generous meas- 

 ure qti/I wif>»rvn+ Fig. 39. — Lesser migratory locust (Melanoplus atlanis). (From 

 ure, ana Wimout Lugger, Minnesota Experiment Station.) 



doubt are the 



most important single article of diet. During one of the historic out- 

 breaks of the Rocky Mountain locust, the blue grosbeak was found to 

 feed on other grasshoppers among the swarming hordes, and it is cer- 

 tain that the pest itself was not overlooked. A very closely-related 

 species, called in contradistinction the lesser migratory locust (Me- 

 lanoplus atlanis, fig. 39), has been identified from the stomachs exam- 

 ined. 



But little insect food in addition to that above discussed is con- 

 sumed. A fly or a wasp is rarely secured, and one ant and a saw- 

 fly larva were eaten. Besides insects, a small amount of other animal 

 matter was present in the stomachs. Spiders or their egg-sacs were 

 eaten by 2 birds and snails by 9. The latter may be taken in lieu 

 of gravel. 



Mineral Matter. 



Only 2 adult blue grosbeaks out of a total of 38 had taken inor- 

 ganic mineral matter, and the percentage of such material is only 

 0.63. Of 13 nestlings, 7 contained mineral matter in quantity suffi- 

 cient to make the average for the whole group 8.3 percent, which is 



