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 Nov.,1911 RELATION OF BIRDS TO AN INSECT OUTBREAK 199 mate and lay their eggs in the fall, but more often they live through the winter and lay their eggs in the early spring (see fig. 68). In 1902 this same species of butterfly was abundant in the north. Since that time it has not been seen in any great numbers until this year. In the memory of the oldest inhabitants of Siskiyou County, the numbers of butterflies this year far exceed those of any previous year. The newspaper accounts were often exagger- ated, and yet few people who did not see the swarms which filled the air, can have any realization of the great numbers. In order to get some idea of the numbers, counts were made. In damp places or along the banks of streams, where the but- terflies had gathered to drink, as many as 150 individuals were counted in one square foot. Often the ground would be blackened by them for mauy square yards (see fig. 70). Fig. 69. PUPAE AND ADULTS OF Euonia californica. IN ONE OF THE PUPAE, THE INSECT HAS BEEI DESTROYED BY SOME BIRD; IN THE OTHER BY OME PARASITE. THE LATERAL VIEW OF AN ADULT SHOWS THE DARK UNDER SUR- FACE OF THE WING, AND THE DORSAL VIEW, THE COLOR PATTIRN OF THE In order to estimate the numbers flying, counts were made of the individuals passing between two fir trees about twenty feet high and standing about thirty feet apart. The counts for ten successive minutes between 4:40 and 4:50 ?. M. on August 20, were as follows: 1st minnte ....................... 105 6th minute ....................... 100 2rid " . ...................... 119 7th ". .................... 96 3rd " . ...................... 130 8th ". ..................... 102 4th " . ...................... 102 9th ". ..................... 83 5th " . ..................... 134 loth ". ..................... 112 verage per minute ...... 108.