266 THE CANADIAN ENTOMOLOGIST 



This method of reaching the surface together with other snow habits of the 

 insect were well illustrated in an enormous outbreak of Achoriites socialis Uzel 

 that I observed one day in February, and which, may he taken as a good example 

 of snow appearances in general. But here, in order to explain how I came 

 on the insects on this occasion, I must make a slight digression. 



Achorutes socialis has a strong and distinctive but inconstant smell. I 

 have never seen any reference to it in literature, but Dr. Folsom tells me that 

 he has noticed it both from A. socialis and from the closely allied A. packardi. 

 It is not easy to describe, but it reminds me most of the srrell of that favourite 

 fruit-salad of the small boy: a slice of raw turnip. Sometimes the scent can 

 be caught from half a dozen captives in a vial, at other times a hundred of them 

 give off no appreciable odour whatever. Similarly, during an extensive emergence, 

 sometimes no smell at all can be noticed, and sometimes it is so strong that it 

 is possible to discover an outbreak of the insects by the sense of smell alone. 

 The first time I experienced this I was walking through a hardwood bush one 

 morning in December, and not thinking particularly of springtails, when it 

 suddenly occurred to me that a few moments before I had smelled Achorutes 

 socialis. I retraced my steps, and about 50 feet back there they were to one 

 side of my path, coming out of a mossy log in thick, blue-Dlack agglomerations. 



It was in the same way that I discovered the insects this day in February. 

 A favcurite winter trail of mine at one place goes down the middle of a beaver 

 meadow about half a mile long by 200 yards wide, through which in summer a 

 small, sluggish stream meanders to a sandy bay of the Ottawa River. The 

 meadow is bordered by an open growth of moisture- loving shrubs and trees, 

 such as speckled alders, black and white ashes and soft maples These occupy 

 a strip a couple of hundred feet wide, and on the drier ground behind, cedars, 

 spruces, hemlocks and pines are mixed with elms and hard maples. 



The temperature had been above freezing point for the preceding 24 hours, 

 and three inches of wet snow had fallen in the night, bringing the total depth 

 on the ground up to 18 inches. At noon the thermometer stood at 36° F., the 

 sky was overcast, and the relative humidity was 91 per cent. It was not the 

 kind cf day that most people would choose for a snow-shoe tramp for the snow 

 was very wet and the going heavy, but it was ideal snow-flea weather, so I was 

 out bright and early. There was the usual sprinkling of Isotomas in the drier 

 woods and Achorutes in the damper situations, but I found nothing out of the 

 common until I reached the beaver meadow. Here, while pursuing my ac- 

 customed track, as I paused a moment to pick up a specimen, in an instant I 

 caught the familiar smell of Achoriites socialis, wind-borne from the south side 

 of the meadow. I followed up the scent and among the ashes and soft maples 

 I found them. 



They were coming up to the surface through the spaces in the snow around 

 the trees and shrubs, some climbing the snow wall, and some the trunks and 

 stems. Most of the latter sprang off on to the snow, but a good many remained 

 on the trees, and either gathered in blue patches here and there or went wander- 

 ing up the trunk, although not to any height, for above 10 feet I could find 

 none. The principal area of emergence was between 50 ft. and 100 ft. wide, 

 and extended all along the south side of the marsh, — a distance of about 800 

 yards. Over this space there were from 50 to 100 insects to the square foot. 



