INSECT METAMORPHOSIS 



connected with its transformation, is subservient to the 

 function of procuring food. Most species feed on plants 

 and live in the open (Fig. 131; A); but some tunnel into the 

 leaves (B), into the fruit (D), or into the stem or wood 

 (C). Other species feed on seeds, stored grain, and cereal 

 preparations. The caterpillars of the clothes moths, 

 however, feed on animal wool, and a few other caterpillars 

 are carnivorous. 



The whole structure of the caterpillar (Fig. 136) be- 

 tokens its gluttonous habits. Its short legs (L, AbL) keep 

 it in close contact with the food material; its long, thick, 

 wormlike body accommodates an ample food storage and 

 gives space for a large stomach for digestive purposes; its 

 hard-walled head supports a pair of strong jaws {Md), and 

 since the caterpillar has small use for eves or antennae, 

 these organs are but little developed. The muscle system 

 of the caterpillar presents a wonderful exhibition of com- 

 plexity in anatomical structure, and gives the soft body of 

 the insect the power of turning and twisting in every con- 

 ceivable manner. In contrast to the caterpillar, the moth 

 or the butterfly feeds but little, and its food consists of 

 liquids, mostly the nectar of flowers, which is rich in 

 sugars and high in energy-giving properties but contains 

 little or -none of the tissue-building proteins. 



When we examine the young of other insects that 

 differ markedly from the parent form, we discover the 

 same thing about them, namely, the general adaptation of 

 their body form and of their habits to the function of eat- 

 ing. Not all, however, differ as widely from the parent 

 as does the caterpillar from the moth. The young of 

 some beetles, for example (Fig. 137), more closely re- 

 semble the adults except for the lack of wings. Most of 

 the adult beetles, too, are voracious feeders, and are per- 

 haps not outdone in food consumption by the young. But 

 here another advantage of the double life is demon- 

 strated, for usually the grub and the adult beetle have 

 different modes of life and live in quite different kinds of 



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