HYBERNATION OF INSECTS. 



359 



not, at least in our climate, strictly be said to hybernate, 

 understanding by that term passing the winter in one selected 

 situation in a greater or less degree of torpor, without food. 

 Not to mention Cheimatobia brumata, and some other moths, 

 which are disclosed from the pupa3 in the middle of winter, 

 and can therefore be scarcely regarded as exceptions to 

 the rule, some insects are torpid only in very severe weather, 

 and on fine mild days in winter come out to eat. This is the 

 case with the larva of Euprepia fuliginosa 1 ; and Lyonet 

 asserts that there are many other caterpillars which eat and 

 grow even in the midst of slight frost. 2 Amongst perfect in- 

 sects, troops of Trichocera hiemalis, the gnat whose choral 

 dances have been before described, may be constantly seen 

 gamboling in the air in the depth of winter when it is mild 

 and calm, accompanied by the little Psychoda, so common in 

 windows, several Muscidce, spiders, and occasionally some 

 Aphodii and StaphylinidcB : and the societies of ants, as well 

 as their attendant Aphides, are in motion and take more or 

 less food during the whole of that season, w hen the cold is not 

 intense. The younger Huber informs us that ants become 

 torpid only at 2° Reaum. below freezing (27° Fahrenheit), 

 and apparently endeavour to preserve themselves from the 

 cold, when its approach is gradual, by clustering together. 

 When the temperature is above this point they follow their 

 ordinary habits (he has seen them even walk upon the snow), 

 and can then obtain the little food which they require in 

 winter from their cows, the Aphides, which, by an admirable 

 provision, become lethargic at precisely the same degree of 

 cold as the ants, and awake at the same period with them. 3 

 Humboldt also found insects upon the Cordilleras, above the 

 limits of snow, which, although not natives of this altitude, re- 

 tained their vivacity at this low temperature. 4 



i Brahm, Ins. Kal. ii. 31. 2 Lesser, I. i. 255. 



3 Eecherches, 202. In digging in my garden on the 2Gth of January, 1817, 

 I turned up in three or four places colonies of Myrmica rubra Latr. in their 

 winter retreats, each of which comprised apparently one or two hundred ants, 

 with several larvae as hig as a grain of mustard, closely clustered together, 

 occupying a cavity the size of a hen's egg, in tenacious clay, at the depth of six 

 inches from the surface. They were very lively ; but though Fahrenheit's ther- 

 mometer stood at 47° in the shade, I did not then, nor at any other time during 

 the very mild winter, see a single ant out of its hybernaculum. 



4 Burmeister, Manual of Ent. 508. 



A A 4 



