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 196 THE CONDOR Vol. XIII were collected. It was found that "birds of the most varied character and habits, migrant and resident, of all sizes from the tiny wren to the blue jay, birds of the forest, garden, and meadow, those of arboreal and those of terrestrial habits, were certainly either attracted or detained here by the bountiful supply of insect food and were feeding freely upon the species most abundant. That thirty-five percent of the food of the birds congregated here should have consisted of a single species of insect is a fact so extraordinary that its meaning cannot be mistaken." Professor Forbes also found that the same percentage of other caterpillars had been eaten by the birds in the orchard as had been eaten by birds taken in other localities and that the cankerworm ratios had apparently been added to those of other caterpillars. Fig. 67. DEPOLIATED SNOW BRUSH (Ceanothus cordulalus), THE RESULT OF THE V'ORK OF THE LARVAE OF Eugonia californica. PHOTOGRAPH TAKEN NEAR SISON, SISKIOU COUNTY, CALIIORNIA, AUGUST 24, 1911 The most prolonged series of studies of the relation of birds to insect out- breaks was that by Professor Samuel Aughey, who for thirteen years studied the extent to which birds fed on the Rocky Mountain locust or grasshopper during the periodic outbreaks of that insect. His tabulated results show that birds of every description from the pelican to the tiny hummingbird fed to a very large extent on the grasshoppers. The relation of birds to the army worm, which is one of the best known of the periodical pests, has received some investigation at the hands of the economic ornithologist. Professor B. H. Warren, the state zoologist of Pennsylvania, mak-