HYBERNATION OF INSECTS. 557 



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

 there are some, though but (ew, which cannot, at least in our climate, 

 strictly be said to hybernate, understanding by that term passing the win- 

 ter 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 pupae 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} ; and Lyonet 

 asserts that there are many other caterpillars which eat and grow even' in 

 the midst of slight frost.^ Amongst perfect insects, troops of Trichoccra 

 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 win- 

 dows, several Muscidce, spiders, and occasionally some Aphodii and Staphy- 

 linidcB : 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 endeavor 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.^ 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 tempera- 

 ture.'* 



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

 as Podura 7iivaUs L., Boreus hiemalis Latr., and the singular apterous 

 insect, first described by Dalman, Chionea araneo'ides^, all of which run 

 with agility on the snow itself; and which last, both from its spider-like 

 form and singular habitat, must, as Macquart has well observed^, have 

 caused its fortunate discoverer as much astonishment as that felt by the 



47° to 52° every day, and at night rarely below 40° ; in fact, a week much finer than we 

 can often boast of in May : the 27th of the month was the most delightful day of the whole : 

 'the air swarmed with Trichocera hiemalis, Psj/chodce, Sind numerous other Diptera, and the 

 bushes were hung with the lines of the gossamer-spider as in autumn. Yet, with the 

 exception of Aphodius contaminatus. I did not observe a single coleopterous insect on the 

 wing, nor even an individual tempted to crawl on the trunks of the trees, under the dead 

 bark of which I found many in a very lively state. Five or six individuals of Haltica 

 Nemornm were still very lethargic; and two of Geotrvpes 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. 



» Brahm, Ins. Kal. ii. 31. * Lesser, 1. i. 255. 



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

 in three or four places colonies of iliyi'?;(icfl rubra Latr. in their winter retreats, each *'of 

 which comprised apparently one or two hundred ants, with several larvse as big as a grain 

 of mustard, closely clustered together, occupying a cavity the size of a hen's egg, in tena- 

 cious 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. 



* Bormeister, Manual of Eat. 508. 



6 Kongl. Vet. Acad. Handling. 1816, 104. « Dipteres, i. 74. 



47* 



