48 BIKDS OF CALIFORNIA AFFECTING FRUIT INDUSTRY. 



soon acquire the habits of its eastern relative. From the material at 

 hand this warbler appears to be even more exclusively insectivorous 

 than the species last discussed. This may arise from the fact that 

 it stays in the fruit districts during summer, when insects are most 

 numerous; but it must be remembered that this is also the season 

 when fruit and vegetable food generally are most abundant. 



William Prond, of Chico, Butte County, thus recounts the efficient 

 service of this and other warblers : 



On Rancho Chico is a fine collection of roses, all of which are more or less 

 liable to attacks from Aphis rosea, but are perfectly free from other insects. 

 I attribute this to the protection of small birds, among the most active of which 

 are Dendroica (estiva, * * * HelmintJwphila celata, Regains calendula. 



The following statements in regard to the food of the summer 

 warbler are based on the examination of 98 stomachs, all collected 

 from April to October, inclusive, 



Animal food. — The animal food, composed entirely of insects and 

 a few spiders, amounts to over 97 percent. The largest item is 

 Hymenoptera, which amounts to over 30 percent, about half of which 

 are ants. The remainder are small bees and wasps, some of which 

 are probably parasitic species, though none were positively identi- 

 fied. The insects of this order must be favorite food, as they are 

 eaten with remarkable regularity and constitute an important per- 

 centage of the diet in every month represented. Caterpillars, with a 

 few moths, aggregate over 18 percent. The greater number are 

 eaten in spring and early summer, but in fall they give place to other 

 insects. 



Beetles form nearly 16 percent of the diet, and embrace about a 

 dozen families, of which the only useful one is that of the ladybirds 

 (Coccinellidse), which are eaten to a small extent. The great bulk 

 of the beetle food consists of small leaf -beetles (Chrysomelidse), with 

 some weeAuls, and several others. One stomach contained the remains 

 of 52 specimens of Notoxus alameda\ a small beetle living on trees. 

 Bugs (Hemiptera) constitute over 19 percent of the food, and are 

 eaten regularly every month. Most of them consist of leaf -hoppers 

 (Jassidse) and other active forms, but the black olive scale appeared 

 in a number of stomachs. Plant-lice were not positively identified, 

 but some stomachs contained a pasty mass, which was probably made 

 up of these insects in an advanced stage of digestion. 



Flies seem to be acceptable to the summer warbler ; they are eaten 

 to the extent of nearly 9 percent. Some of them are of the family 

 of the house fly, others are long-legged tipulids, but the greater num- 

 ber were the smaller species commonly known as gnats. A few 

 small soft-bodied Orthoptera (tree-crickets), a dragon-fly, and a few 

 remains not identified, in all about 5 percent, made up the rest of 

 the animal food. 



