98 BIRDS OF CALIFORNIA AFFECTING FRUIT INDUSTRY. 
The food of the bluebird consists of elements whose consumption 
is almost wholly a benefit to the farmer. Four-fifths of it is insects; 
only a small portion of these are useful, and these to a limited extent. 
In the investigation of the food of the bluebird 187 stomachs were 
examined. This number is not so large as could be desired, and, 
moreover, was rather irregularly distributed over the year. Only 
one stomach was obtained in May, and only one in April, while the 
number for several other months are too few. Geographically they 
fairly well represent the fruit-growing regions of the State from as 
far south as San Bernardino northward to Santa Rosa. The food 
found in the stomachs consists of animal matter, 82 percent; vege- 
table, 18 percent. 
Animal food—Of the animal portion a little less than 12 percent 
consists of predaceous beetles (Carabidee), which are usually reck- 
oned as useful. There are, however, many exceptions to this rule, 
and since most of the species of this family are wonderfully abun- 
dant it is not probable that the bluebird does much harm by eating 
them. It is believed, moreover, that this record of Carabide is above 
the normal, for the one bird taken in April had eaten 90 percent of 
these beetles, thereby raising the average of the whole. In August, 
on the other hand, not one of the five birds examined had eaten a 
carabid. Had these months been omitted from the reckoning the 
average would have been reduced to about one-third of the present 
figure, which is probably much nearer the truth. 
Other beetles amount to over 17 percent of the food, and were 
distributed among about a dozen families, all of them harmful, except 
three or four ladybirds (Coccinellide), which are useful. 
Caterpillars evidently are a favorite food, and probably are eaten 
in every month, though evidence is wanting for April and May. 
They amount to over 17 percent of the year’s food. Few of these 
insects are eaten in spring and early summer, many in fall and winter. 
As practically all caterpillars are harmful, this item of diet counts 
entirely in the bird’s favor. 
Grasshoppers and crickets, mostly the former, were eaten in every 
month except April, but a greater number of stomachs would prob- 
ably give a different result. They amount to a little less than 24 
percent of the year’s food. They appear in the stomachs of western 
birds at a somewhat earlier date than in those of eastern species. 
In the Atlantic and Central States, August is preeminently the season 
of grasshoppers, and in that month they constitute the principal 
arlicle of diet of many species of birds. The western bluebird eats 
grasshoppers in March to the extent of about 11 percent of its food. 
In June they amount to over 88 percent, and in July reach a maximum 
of nearly 49 percent, or nearly half of all that it eats. In September 
they amount to 40 percent, but decrease rapidly from that time. 
