THE CANADIAN ENTOMOLOGIST 245 



But the most heedless passer-by cannot overlook Achorutes socialis Uzel 

 when it makes up its mind to come out. The vast swarms literally blacken 

 square yards of the snow around the principal foci from which they emerge. 

 On level surfaces they may be as thick as 500 to the square foot, while in hol- 

 lows and depressions in the snow — such as foot-prints — from which they cannot 

 easily escape, they sometimes accumulate in solid masses that could be ladled 

 out with a spoon. (I find the mark of a No. II shoe- pack an admirable snow- 

 flea trap, — ^and to prevent unkind inferences I hasten to point out that in winter 

 this footwear calls for at least four pairs of heavy socks.) Spreading out from 

 these centres, the distribution becomes thinner, though for acres the insects 

 often run from 10 to 50 to the square foot, and examination of a yard or so of the 

 surface anywhere over miles of country is almost certain to show two or three 

 specimens leaping and clambering among the snow particles. 



Most writers speak of snow- fleas as occurring in the spring, and it is true 

 that some species of them seem to come out only at that season, and in general 

 they are most abundant towards the end of the winter. But it is the effect of 

 the mild weather whenever it occurs and not the season that brings them out, 

 for most of them can be found on the snow every month from November to 

 April whenever the rising temperature approaches the freezing point. Those 

 excellent field-naturalists, the Red Indians, noticed this. Among the native 

 weather lore recorded by F. W. Waugh in his "Iroquois Foods," the snow-fleas 

 are said to indicate mild weather, and the Onondagas, Mr. Waugh says, called 

 them "soft weather fleas." 



But it should be borne in mind that while the snow- flea tide rises in direct 

 relation with the temperature, the soft weather is not the determining cause 

 of the insects' emergence. The real factor is the amount of moisture in the 

 atmosphere. In mild weather, the large quantity of water vapor released by 

 the melting snow soon brings the humidity, both relative and absolute, to a 

 high figure, and the snow-fleas, finding a more 



(To be continued.) 



NEW APHIDS FROM OAKS. 



*BY W. M. DAVIDSON, U. S. BUREAU OF ENTOMOLOGY. SACRAMENTO, CALIFORNIA. 



Vacuna californica, sp, nov. 



Vacuna dryophila Schrank?. Davidson, Journal Econ. Ent., Vol. X, Apr., 

 1917. 



In April, 1917, issue of the Journal of Economic Entomology, the writer 



referred this species doubtfully to dryophila Schrank of Europe, only a single 



winged individual having been taken up to the time the article (Little- known 



Western Plant- Lice II) was submitted for publication. Since that time more 



winged insects have been collected, and all prove to differ from the typical 



dryophila in the same manner as the first. It appears, therefore, that the 



Californian insect is worthy of specific rank. 



*Published with the permission of the Secretary of Agriculture. 

 November, 1919 



