74 BIRDS OF CALIFORNIA AFFECTING FRUIT INDUSTRY. 



entirely filled with these insects, and in another 300 were counted. 

 Considered in relation to the food of the year, however, they amount 

 to only 1.6 percent. Many of these plant lice are of the kind com- 

 monly called woolly aphids, because their bodies are covered with 

 a white cottony appearing substance, really a white wax, which 

 exudes from the body of the insect. While the destruction of this 

 small number of insects may seem insignificant, yet the goldfinch is 

 one of the forces that keep within reasonable bounds the immense 

 swarms of these prolific and pestiferous creatures. By far the greater 

 number of these aphids were found in the crops and not in the 

 stomachs; but as many of the latter were not accompanied by the 

 crops, possibly the goldfinch consumes many more of these insects 

 than is shown above. Then, too, aphids are very fragile, and by the 

 time they reached the stomach many of them were probably too much 

 reduced to be identified. 



Vegetable food. — The vegetable food may be divided into 4 cate- 

 gories: Fruit, grain, weeds, and miscellaneous matter. Fruit was 

 found in 7 stomachs, all taken in June, July, and August. In one 

 case it was a berry with small seeds, which have not yet been identified ; 

 in the others it could be classed only as fruit pulp. Altogether it 

 amounts to three-tenths of 1 percent of the year's food. A single 

 kernel of wheat was found in 1 stomach taken in December. Weed 

 seed is the standard food of this goldfinch. It aggregates over 96 

 percent of the year's diet, and in January and March nothing else is 

 eaten. The month of least consumption, August, shows over 86 per- 

 cent, and in every other month it is above 94. While several species 

 are eaten freely, the chief is the Napa, or bur thistle (Centaur ea meli- 

 tensis), which was found in 243 of the 476 stomachs, and would seem 

 to be the staff of life of the goldfinch. It is a small hard seed covered 

 with an apparently siliceous shell, with a hook at one end and a 

 bunch of stiff bristles at the other. a Generally the bird skillfully 

 removes this shell and swallows only the starchy pulp. Many kinds 

 of weed seed were found in the 469 stomachs examined, and only 7 

 did not contain any; 394 contained nothing else. 



Other vegetable food, some of it not satisfactorily identified and 

 some of it rubbish, amounts to 1J percent of the whole. In regard 

 to eating seeds of garden vegetables on seed farms, what was said of 

 the willow goldfinch will apply with equal truth to this species. 

 What seemed to be the petals of flowers were found in a few stomachs, 

 but did not reach a respectable percentage. It does not appear 

 that the green-backed goldfinch requires any other food than weed 

 seed, and of this one or two varieties suffice. The following is a list 



a PL II, fig. 1, Part I, opp. p. 16. 



