Insect metamorphosis 



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five pairs of unjointed clasping abdominal " pro-legs." 

 Other abdominal appendages are known on the larvae of 

 other insects, and even in the embryos of some whose larvae 

 are campodeiform. These facts make it likely that the 

 primitive form had many legs. 



The larvce of Insects vary enormously in habit and in structure, and 

 exhibit numerous adaptations to conditions of hfe very different from 

 those of the parent. Thus caterpillars, which are usually plump and 



Fig. 223. — Development of blow-fly {CaUiphora erythrocephala). 

 — After Thompson Lowne. 



The lower figure (A) shows the full-grown larva (maggot). Note, 

 compared with the caterpillar, the absence of appendages, 

 except those about the mouth ; h., the large hooks connected 

 with the maxillae ; pi., pro-legs. 



The upper figure (B) shows the pronymph removed from the pupa- 

 case. In the abdominal region the imaginal discs are shown ; 

 /., rudiments of legs ; w., of wings. 



tense, so that a peck from a bird's bill may cause them to bleed to death, 

 even if no immediate destruction befall them, are protectively adapted 

 in many different ways. Their colours arexjften changed in harmony 

 with those of their surroundings , some palatable forms are saved by 

 their superficial resemblance to those which are nauseous ; a few strike 

 " terrifying attitudes " ; while others are like pieces of plants. 



Internal metamorphosis. — In Insects with no marked 

 metamorphosis, or with merely an incomplete one, the 

 organs of the larvae develop gradually into those of the 

 adult. But in Insects with complete metamorphosis there 

 is a marvellous internal reconstruction during the later 



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