FOOD OF ROBINS AND BLUEBIRDS. 



27 



per cent. No honey bees were found. Hemiptera (bugs) were 

 found in the stomachs taken every month but April and August, 

 but the quantity in each month varied greatly and irregularly. The 

 average for the year is 6.38 per cent. A small quantity of black 

 olive scales {Saissetia olece) were found in one stomach. 



Caterpillars appear to be one of the western bluebird's favorite 

 foods. These and a few adult moths were found in the food of every 

 month except May, but as only two stomachs were taken in this 

 month the omission is probably accidental. Their appearance in 

 the stomachs is very irregular, but it would probably be more uni- 

 form if more stomachs were available. March is the month of 

 greatest consumption (50.18 per cent), but August has nearly as 

 much, and April and November are not far behind. The average 

 for the year is 20.25 per cent. No special pest was identified, but 

 practically all caterpillars are harmful. 



Grasshoppers, which constitute the largest and most regular item 

 of the western bluebird's food, are not eaten quite so freely as by the 

 eastern bird, although in the Pacific coast region they can be obtained 

 at all times of the year. The least consumption occurs in January, 

 with 1.81 per cent of the whole food, and the greatest in May with 

 49.50 per cent. In the East the maximum of grasshopper eating 

 with nearly all species of insectivorous birds is in August or there- 

 about. The average for the year with the western bluebird is 21.29 

 per cent, a little less than the record of the eastern species in a much 

 shorter season. 



Diptera (flies) are evidently not a favorite food of the western 

 bluebird. In four months none were found, and in March, only, do 

 they amount to 1 per cent ; in that month they are eaten to the extent 

 of 5.64 per cent of the diet, but the average for the year is only 0.72 

 per cent. A few other insects not included in the foregoing amount 

 to 0.44 per cent. Spiders were found in the stomachs taken every 

 month, but not in large quantities, the average for the year being 

 1.94 per cent. Myriapods (thousand-legs) were eaten still less than 

 spiders. They appeared in the food of only five months, and amount 

 to only 0.17 per cent. A few angleworms, snails, and sow bugs 

 amount to 0.11 per cent, and complete the items of animal food. 



Following is a list of the animal constituents of the western blue- 

 bird's food as far as identified, and the number of stomachs in which 

 found : 



HYMENOPTERA. 



Messor andrei (ant) 



COLEOPTERA. 



Amara aurata 



Silptia ramosa 



COLEOPTERA— Continued. 



Hippodamia convergent 10 



CoccineUa califomica 3 



Lebasiella macuHcollis 1 



YriUetta murrayi 1 



Polycaon stouti 1 



