BIRDS IN RELATION TO THE ALFALFA WEEVIL. 47 



Midvale, West and South Jordan, Sandy, and Riverton, an area in 

 which this bird is by far the most abundant species. 



May 1 to May 15. Examination of birds collected during this 

 interval showed that the parent birds were already visiting alfalfa 

 fields for food for the hungry nestlings. The weevils fed to the 

 young were adults which had hibernated, a very important economic 

 service when is considered the potential harm of each pair of weevils 

 during the course of a season, as embodied in their progeny. 



About one-half of the total animal food, 14 per cent, consisted of 

 the weevil. Thirteen of the 16 birds collected had fed on this insect, 

 indicating that this food is probably picked up whenever found. 

 These nestlings had eaten a total of 218 adult weevils, or an average 

 of 13f per bird. A brood of three, about 2 or 3 days old, had eaten 60, 

 50, and 32 per cent, representing 58, 41, and 28 weevils, respectively. 



The contents of these stomachs consisted of 28.06 per cent animal 

 and 71.94 per cent vegetable matter. Of the animal food other than 

 weevils 4.19 per cent was caterpillars, while 4.37 per cent consisted 

 of scarabaeid beetles of the genus Aphodius. Ground beetles aggre- 

 gated 2.56 per cent; Hymenoptera, 1.12 per cent; and Orthoptera 

 (grasshoppers and crickets), slightly less than 1 per cent. The 

 remaining portion of animal matter was composed of other insects 

 in small quantities. 



The largest portion of the vegetable food was wheat, found in 15 

 of the 16 stomachs, and amounting to 65.62 per cent. 



May 16 to May, 31. The weevil was eaten by the 530 birds to the 

 extent of 36.12 per cent of the stomach contents, which is the highest 

 proportion of this food eaten in any of the semimonthly periods cov- 

 ered. As this figure was obtained from the examination of so large 

 a series of stomachs, it doubtless is not far from a true representation 

 of what these young birds do at this time of year. The remarkable 

 persistency with which the parent birds seek this food for their 

 young is well shown. Of 530 young birds, only 19, or 1 out of about 

 every 28, had failed to eat the weevil. 



Among the birds notable for their stomach contents were 7 in 

 which the weevil composed the entire food, 11 in which it amounted 

 to 90 per cent or over, and 16 in which it was 80 per cent or over. 

 The number of insects that may be contained in the stomachs of these 

 young birds is remarkable. A nearly fledged young of a brood of 

 four had eaten no less than 20 adults and 110 larvae, while the re- 

 maining three had consumed 27 adults and 29 larvae together. Two 

 young birds, about a week old, had eaten 62 adults and 92 larva? 

 between them. A brood of four, about 4 days old, had taken, respec- 

 tively, 38 adults and 33 larvae, 33 adults and 65 larvae, 41 adults and 

 67 larva?, and 25 adults and 60 larvae, or an average of 34J adults and 

 56 J larvae apiece, equaling 51 per cent of the stomach contents. An- 



