274 Metamorphoses of Insects. 



infancy to old age, they appear at one period under a shape so 

 diflerent from that which they finally assume ; and why should 

 they pass through an intermediate state of torpidity so extraor- 

 dinary ? I can only answer that such is the will of the Creator, 

 who doubtless had the wisest ends in view, although we arc 

 incompetent satisfactorily to discover them. Yet one reason for 

 this conformation may be hazarded. A very important part 

 assigned to insects in the economy of nature, as I shall hereafter 

 show, is that of speedily removing superabundant and decaying 

 animal and vegetable matter. For such agents an insatiable 

 voracity is an indispensible qualification, and not less so unusual 

 powers of multiplication. But these faculties are in a great 

 degree incompatible. An insect occupied in the work of repro- 

 duction could not continue its voracious feeding. Its life, therefore, 

 after leaving the egg, is divided into three stages. In the first, as 

 larva, it is in a state of sterility ; its sole object is the satisfying 

 its insatiable hunger ; and, for digesting the masses of food which 

 it consumes, its intestines are almost all stomach. This is usually 

 by much the longest period of its existence. Having now laid up 

 a store of materials for the development of the future perfect 

 insect, it becomes a pupa ; and during this inactive period the 

 important process slowly proceeds, uninterrupted by the calls of 

 appetite. At length the perfect insect is disclosed. It now often 

 requires no food at all ; and scarcely ever more than a very small 

 quantity ; for the reception of which its stomach has been con- 

 tracted, in some instances, to a tenth of its former bulk. Its 

 almost sole object is now the multiplication of its kind, from which 

 it is diverted by no other propensity ; and this important duty 

 being performed, the end of its existence has been answered, and 

 it expires. 



It must be confessed that some objections might be thrown out 

 against this hypothesis, yet I think none that would not admit of 

 a plausible answer. To these it is foreign to my purpose now to 

 attend, and I shall conclude this letter by pointing out to you the 

 variety of new relations which this arrangement introduces into 

 nature. One individual unites in itself, in fact, three species, 

 whose modes of existence are often as different as those of the 

 most distantly related animals of other tribes. The same insect' 

 often lives successively in three or four worlds. It is an inhabit 

 ant of the water during one period, of the earth during another 

 and of the air during a third ; and fitted for its various abodes hr 



