FOOD OF ROBINS AND BLUEBIRDS. 7 



In this last case the bird probably had the good fortune to find sev- 

 eral colonies. March flies are not considered very harmful insects, 

 but are prolific breeders, and that they do not do more damage is 

 probably because they are so persistently preyed upon by robins. 

 In February and March the number of these larvae eaten is about 

 10 per cent of the bird's diet. In other months it is considerably 

 less. The average for the year is 3.14 per cent. A few crane flies 

 (Tipulidse) and a few bits of other Diptera were taken by robins, 

 but they do not constitute an appreciable percentage of the food. 



Lepidoptera (mostly caterpillars) form a regular and fairly 

 abundant constituent of the robin's diet. The maximum consump- 

 tion occurs in May, when this item amounts to 23.96 per cent of the 

 food. After this it gradually decreases to a little more than 1 per 

 cent in November, when it again rises toward its maximum. Owing 

 to the soft nature of these insects, very few can be identified. The 

 army worm (Ileliophila unipuncta) was recognized in six stomachs, 

 but was probably represented in many more; the codling moth 

 caterpillar (Carpocapsa pomonella) was found in two stomachs; a 

 cabbage worm {Pontia protodice) in one; and the yellow-necked 

 apple-tree worm (Datana ministra) in three. Undoubtedly many 

 more destructive species were contained in the food, though un- 

 recognizable, but as practically all caterpillars are harmful, any de- 

 struction of them may be set down to the credit of the bird. The 

 total consumption amounts to 9.04 per cent of the food. 



Orthoptera (grasshoppers and crickets) as a general rule are ac- 

 ceptable food for insectivorous birds, and when abundant are eaten 

 by almost every species. The robin, however, does not display any 

 special fondness for them except during the short time when they are 

 most abundant. The west-coast robin evidently relishes these crea- 

 tures even less than does his eastern relative, but this perhaps is 

 partly accounted for by the fact that but few stomachs of the west- 

 ern robin can be taken in the summer, as the bird spends that season 

 either in the far .north or in high mountain regions. It is remark- 

 able, however, that as a general rule western birds do not eat grass- 

 hoppers with the gusto shown by the corresponding eastern species. 

 The robin consumes the greatest quantity of grasshoppers from June 

 to September, when 73 per cent of the total number taken during 

 the year are eaten, or somewhat more than 10 per cent of the whole 

 food. In August, as would be expected, the consumption is greatest 

 and amounts to 17.33 per cent. In the same months the meadowlark 

 eats grasshoppers to the extent of 67 per cent of his monthly diet. 

 The average annual consumption by the robin is only 4.76 per cent, 

 while with the meadowlark it is 28.30. It is evident that during 

 most of the year these insects are eaten by the robin only when noth- 

 ing better is at hand. Melanoplus devastator, a near relative of the 



