HYBERNATION OF INSECTS. 523 



All insects, however, do not undergo this degree of torpidity. In fact, 

 there are some, though but few, which cannot, 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 Euprepiafuliginosa l ; and Lyonet asserts that 

 there are many other caterpillars which eat and grow even in the midst of 

 slight frost. 2 Amongst perfect insects, troops of Trichocera hiemalis, the 

 gnat whose choral dances have been before described, may be constantly 

 seen gambolling in the air in the depth of winter, when it is mild and calm, 

 accompanied by the little Psychoda, so common in windows, several Mus- 

 cidfB, spiders, and occasionally some Aphodii and Staphylinidce : 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, when 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 clus- 

 tering 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, retained their vivacity 

 at this low temperature. 4 



Lastly, there are some few insects which do not seem ever to be torpid, 

 as Podura nivalis L., Boreus hiemalis Latr., and the singular apterous insect, 

 first described by Dalman, Chionea araneides**, all of which run with agility 

 on the snow itself; and which last, both from its spider-like form and sin- 

 gular habitat, must, as Macquart has well observed 6 , have caused its fortu- 

 nate discoverer as much astonishment as that felt by the botanist who first 

 found the red-coloured Protococcus nivalis (whatever may be decided as to 

 its being a plant or an animalcule) in a similar situation ; or, as may be 

 added, that of M. Lefebvre on first observing the Mantis (JEremiophila), 



were still very lethargic; and two of Geotrupes stercorarius, which I accidentally dug 

 up from their hybernacula in the earth, at the depth of six or eight inches, though 

 the Acari upon them were quite alert, exhibited every symptom of complete torpor, 

 l Brahm. Ins. Kal ii. 81. a Lesser, 1. i. 255. 



3 Recherches, 202. In digging in my garden on the 26th of January, 1817, I 

 turned up in three or four places colonies of Myrmica rubra Latr. in their winter re- 

 treats, each of which comprised apparently one or two hundred ants, with several 

 larvae .as big 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 thermometer 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. 



5 Kongl Vet. Acad. Handling. 1816, 104. Diptere*, i. 74. 



