280 



HALF HOURS WITH INSECTS. 



[Packard. 



means of the two long terminal spines terminating its up- 

 turned extremity it holds the old cast skin over its body 

 like an umbrella. The beetle itself in its resplendent golden 

 hues has been compared, by Wallace, to "glittering dew- 

 drops upon the leaves." In another form, Chelymorpha cri- 

 hraria (Fig. 217 ; a, i)npa), whicli is considerably larger than 

 Cassida, and feeds very much exposed on the silk weed, and 

 sometimes on the raspberry, is also protected by its cast 

 skin, though in a less degree. 



The larva of the common potato beetle of the eastern 

 states (Fig. 218; a, larva; &, c, pupa ; rf, eggs) covers its 

 dull gray soft body with a black mass of its excrement, 



Fig. 217. 



Fig. 218. 



Helmet Beetle and Pupa. 



Young Potato Beetle. 



which is at once a protection from the heat of the sun and 

 the attacks of birds, wiiich probably regard them as any- 

 thing but living and edible insects. 



It would seem, then, that while in the generality of cases 

 insects harmonize in color and often in form with suiTound- 

 ing objects, or even distinctly mimic natnral objects, this is 

 owing in all probability mainly to the physical environment 

 of the animal ; in a few cases, however, there is an appear- 

 ance of design, and natural selection has been the means 

 by which the mimicry has been effected and the species 

 preserved. 



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