76 BIRDS OF CALIFORNIA AFFECTING FRUIT INDUSTRY. 
food contained in a bird’s stomach at a given time is only a fraction 
of the daily consumption, we may infer that not many days pass in 
the life of a bush tit when it does not eat a considerable number of 
scales. 
Before leaving the subject it may be well to add a few words on 
the economic relations of scale-insects in order that the value of the 
work done by the bush tit may be fully appreciated. Mr. Marlatt 
says: 
The most destructive insect enemies of fruits in California are undoubtedly 
the scale insects, few if any other insects, aside from the grape Phylloxera, at 
all approaching them in this respect. Of these, the ones of greatest moment 
and in the control of which vast sums of money are expended are the black 
scale, the red scale, and the San Jose scale. For the olive and citrus plants 
the black scale is the most important, and for the deciduous plants the San 
Jose scale takes similar rank. 
When the immense number of bush tits and other birds in Califor- 
nia that eat scale insects is considered, it becomes evident that the 
aggregate of these pests annually destroyed by them must be enor- 
mous. It may be urged that despite the attacks of birds, scales have 
caused, and still are causing, much damage to fruit trees, and that the 
work of birds alone is inadequate to save the trees from destruction. 
This is undoubtedly true, but 1t must be remembered that the birds 
are confronted with abnormal conditions. The great and rapid 
development of the fruit-growing industry on the Pacific coast and 
the simultaneous and widespread introduction of several new species 
of scales resulted in a sudden increase of these pests, while their ene- 
mies, the birds, enjoyed no such opportunities for increase. In time, 
no doubt, an equilibrium would have been reached, and birds would 
have played an important part in establishing this by exerting a con- 
stant and steady check upon the increase of scales. Unaided, how- 
ever, their numbers are too few to cope with the insects which, under 
favorable conditions of climate and environment and unmolested by 
other natural insect. enemies, multiply to countless myriads. 
The remaining portion of the hemipterous food of the bush tit, 
over 31 per cent, is made up of plant-lice, tree-hoppers (Membracide), 
leaf-hoppers (Jassida), some jumping plant-lice (Psyllidw), and a 
considerable number of false chinch bugs (Vysins angustatus), with 
a few lace-bugs (Tingitidw). Of the plant-lice little need be said. 
As pests to vegetation their reputation is world-wide. No part of a 
plant is free from attack. They infest leaves, trunk, and roots, and 
some of their legions of species prey upon nearly every kind of Jand 
plant. They area frequent element of the food of the tit, but as their 
a Thsect cenit ol in @ sironilel: by C. L. Marhitt, U. 8. Dept. of Agriculture, 
Yeurhook, 1806, p. 220, 
