HYBERNATION OF INSECTS. 435 



those of the Aphis of the ash ; yet in the same exposure 

 those of the former shall be hatched, simultaneously 

 with the expansion of the leaves, nearly a month ear- 

 lier than those of the latter: thus demonstrably prov- 

 ing* that the hybernation of these eggs is not accidental, 

 but has been specially ordained by the Author of na- 

 ture, who has conferred on those of each species a pe- 

 culiar and appropriate organization. 



A much greater number of insects pass the winter 

 in the pupa than in the eg^ state ; probably nine-tenths 

 of the extensive order Lepidoptera, many in Ilymen- 

 optera^ and several in other orders. In placing these 

 pupae in security from the too great cold of winter and 

 the attacks of enemies, the larva; from which they are 

 to be metamorphosed exhibit an anxiety and ingenuity 

 evidently imparted to them for this express design. A 

 few are suspended without any covering, though usu- 

 ally in a sheltered situation. But by far the larger 

 number are concealed under leaves, in the crevices of 

 trees, &c., or inclosed in cocoons of silk or other ma- 

 terials which will be described in a subsequent letter, 

 and often buried deep under ground out of the reach 

 of frost. One reason why so many lepidopterous insects 

 pass the winter as pupae, has been plausibly assigned 

 by Rcisel, in remarking that this is the case with all 

 the numerous species which feed on annual plants. As 

 these have no local habitation, dying one year and 

 springing up from seed in another quarter the next, it 

 is obvious that eggs deposited upon them in autumn 

 would have no chance of escaping destruction ; and that 

 even if the larvae were to be hatched before winter, 

 and to hybernate in that state, they would have no cer- 



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