THE EVIDENCE FROM THE LIFE-HISTORIES OF INSECTS. 261 



of life is just as perfect and as beautiful as in the adult animal. In 

 how important a manner this has acted, has recently been well shown 

 by Sir J. Lubbock in his remarks on the close similarity of the larvae 

 of some insects belonging to very different orders, and on the dis- 

 similarity of the larvae of other insects within the same order, 

 according to their habits of life. Owing to such adaptations," 

 continues Mr. Darwin, " the similarity of the larvae of allied animals 

 is sometimes greatly obscured, especially when there is a division of 

 labour during the different stages of development, as when the same 

 larva has during one stage to search for food and during another 

 stage has to search for a place of attachment. Cases can even be 

 given of the larvae of allied species, or groups of species, differing 

 more from each other than do the adults." 



Now, these are weighty words, because they sum up the reasons 

 why, admitting a general similarity of early development in insects, 

 we should find so much 

 variety in the later de- 

 velopment we name 

 " metamorphosis." 

 They direct our atten- 

 tion to the fact that 

 adult life is not the 

 only period when 

 changes in the con- 

 stitution and form of 

 the living being occur; 

 and they emphasise 

 very clearly the further 

 fact that to changes 

 occurring in the young 

 stages of an animal are 

 due many of the most 

 characteristic and cu- 

 rious details of animal 

 form and growth. It 

 we wish for examples 

 of unlike larvae of in- 

 sects belonging to the same order, we may find any number of such 

 instances amongst the beetles. Some beetle larvae are footless grubs ; 

 others are well provided with legs ; some have feelers, others want 

 feelers ; and variations in form are very numerous indeed. Or 

 among the Neuroptera, an order including the dragon-flies (Fig. 174), 

 day-flies, white ants or termites, and a host of other insects, the 

 larvae differ somewhat ; but the pupae or chrysalides are exceedingly 

 varied, some being quiescent, others active, and others again being 



FIG. 174. DRAGON-FLY AND ITS METAMORPHOSIS. 

 a, larva ; b, pupa ; c, d, perfect insects. 



