The Regulative Action of Birds upon Insect Oscillations. 19 
per cent. Notwithstanding the number of Anomala eaten in the 
orchard, the ratios of the Scarabaeidae are substantially the same, 
as the ordinary food of the robin in May consists largely of June 
beetles. The surplus of Lepidoptera seems to be balanced by a 
deficiency in all the other orders, no one of which rises to the 
average of its ordinary food in May. The loss is greatest, how- 
ever, in the Diptera, which drop from, eleven per cent, to nothing. 
Comparing the record of the fourteen catbirds shot in the 
orchard with that of twenty- two obtained in miscellaneous situa- 
tions, we note, first, that the caterpillars on the first table are 
more than twice those of the second, — twenty-six in the one, and 
twelve in the other; and that this difference is evidently due to 
the fifteen per cent, of canker-worms taken by the birds of the 
first group. This shows that the catbird, like the robin, had 
simply added the canker-worms eaten to its usual ratio of cater- 
pillars. A more striking difference is shown in the totals of 
Coleoptera, which stand at fifty-six per cent, in the orchard birds, 
and twenty-three in the others. This, again, is evidently due to 
the abundance of Anomala hinotata y for when the ratio of this 
insect is subtracted from the total of Coleoptera, the remainder is 
twenty per cent, as against twenty-three of the ordinary food. 
These excessive ratios of Lepidoptera and Coleoptera are com- 
pensated by deficiencies in the Diptera, Arachnida, Myriapoda 
and Orthoptera, especially in the three first named groups. The 
decided preference of this bird for ants is shown by the fact that 
the usual ratio of these insects is scarcely diminished, fourteen 
per cent, having been taken in the orchard and eighteen else- 
where. 
Fourteen of the black-throated bunting ( Spiza americana), 
killed in the orchard, are to be contrasted with twelve shot in 
May from various situations. A striking difference is seen at 
once in the insect ratios, which amount respectively to eighty- 
eight and forty-seven per cent. This surplus of insects eaten by 
the orchard birds is readily traced to the orders Lepidoptera and 
Coleoptera. Of the former these birds had eaten more than three 
times their ordinary average, and of the latter nearly four times 
the usual amount. The excess of Lepidoptera is clearly due, as 
usual, to the presence of the canker-worms, since the balance left 
3 
