THE CANADIAN ENTOMOLOGIST 117 



THE DISASTROUS OCCURRENCE OF VANESSA CALI- 

 FORNICA IN CALIFORNIA AND OREGON DUR- 

 ING THE YEARS 1911-1912. 



BY F. M. WEBSTER, BUREAU OF ENTOMOLOGY, WASHINGTON, D.C. 



The interesting notfe of Mr. J. B. Wallis on the occurrence of 

 this species at Peachland, British Columbia, in 1912, as given in 

 the "Canadian Entomologist" for December, 1912, comes in very 

 appropriately with the notes and observations made by corre- 

 spondents of this Bureau, at Lakeview and Waldo, Oregon, and 

 Willow Ranch, California. As the Bureau of Entomology is not 

 likely to publish on this species in the near future, the information 

 here given may be useful in case there should be a re-occurrence 

 of these caterpillars during the summer of the present year. 



Our first report of injuries by these caterpillars came from 

 Mr. T. V. Hall, of Lakeview, Oregon, under date of July 27, 1911. 

 Mr. Hall states that there had suddenly appeared in his neighbor- 

 hood a worm which had taken almost the entire alfalfa crop. 

 "Also has entirely destroyed the prospects for seed, which usually 

 brings in to the farmers of this neighbourhood about $40,000 an- 

 nually. The worm is from one-half to one inch in length and 

 slender; perhaps 1-8 to 1-12 in thickness, brownish color and sleek 

 appearing surface. It destroys the small tender alfalfa entire. 

 The more mature growth it takes all but the fibre. This worm 

 travels in vast armies. It almost seems as though the ground were 

 in motion when they are in motion. The oldest settlers here state 

 that nothing of the kind has ever appeared here before. This 

 history reaches back at least forty years. We would like well to 

 learn of some method for their destruction, or some way of pre- 

 venting a repetition of the past, for they have caused a total loss 

 to the year's crop." 



The next report came from the same locality, under date of 

 August 25, 1911, from Mr. A. J. Swift, who sent two specimens of 

 these butterflies, which, he says, had been produced in his locality 

 in enormous numbers during that month. Mr. Swift's further 

 statements relative to this occurrence are given in his own words. 

 "So far as known, this butterfly has never occurred here before, 

 or at least in such small numbers as to have escaped comment. 



April. 1913 



