566 HYBERNATION OF INSECTS. 



orological journal ; and I find that the average low^t height of the ther- 

 mometer, in the week comprising the latter end of October and beginning 

 of November, 1816, was 43^° ; while in the week comprising the same 

 days of the month of the end of August and beginning of September it was 

 only 44?° — a difference surely too inconsiderable to build a theory upon. 



1 have entered into this tedious detail, because it is of importance to 

 the spirit of true philosophizing to show what little agreement there often 

 is between facts and many of the hypotheses which authors of the present 

 day are, from their determination to explain every thing, led to promulgate. 

 But in truth there was no absolute need for imposing this fatigue upon 

 your attention ; for the single notorious consideration that in this climate, 

 as well as in more southern ones, we not unfrequently have sharp night- 

 frosts in summer, and colder weather at that season than in the latter end 

 of autumn and beginning of winter, and yet that insects do hybernate at 

 the latter period, but do not at the former, is an ample refutation of the 

 notion that mere cold is the cause of the phenomenon. If, indeed, the 

 hybernacula of insects were simply the underside of any dead leaf, clod, 

 or stone that chanced to be in the neighborhood of their abode, it might 

 still be contended, that such situations were always resorted to by them on 

 the occurrence of a certain degree of cold, but that they remained in them 

 only when its continuance had induced torpidity ; and it seems to have 

 been in this view that most reasoners on this subject have regarded the 

 hybernation of the larger animals, to which they have exclusively directed 

 their attention. But had they been acquainted (as surely the investigators 

 of such a question ought to have been) with the economy of the class of 

 insects, in which not merely a few species, as among quadrupeds, but one 

 half or three fourths of the whole, in our climates, hybernate, they would 

 have known that their hybernacula are in general totally distinct from their 

 ordinary retreats in casual cold weather ; and that many of them even 

 fabricate habitations requiring considerable time and labor, expressly for 

 the purpose of their winter residence — which last fact in particular, on 

 their theory, admits of no satisfactory explanation. We may say, and 

 truly, that the sensation of fatigue causes man to lie down and sleep ; but 

 we should laugh at any one who contended that this sensation forced him 

 first to make a four- post bedstead to repose upon. 



In the second place, if we grant for a moment that it is cold which 

 drives insects to their hybernacula, there are other phenomena attending 

 the state of hybernation, which, on this supposition, are inexplicable. If 

 cold led insects to enter their winter quarters, then they ought to be led 

 by the cessation of cold to quit them. But, as has been before observed, 

 we have often days in winter milder than at the period of hybernating, 

 and in which insects are so roused from their torpidity as to run about 

 nimbly when molested in their retreats ; yet, though their irritability must 

 have been increased "by a two or tliree months' inactivity and abstinence, 

 they do not leave them, but quietly remain until a fresh accession of cold 

 again induces insensibility. 



In short, to refer the hybernation of insects to the mere direct influence 

 of cold is to suppose one of the most important acts of their existence 

 given up to the blind guidance of feelings which in the variable climates 

 of Europe would be leading them into perpetual and fatal errors — which 



