CHAPTER VI. 



THE METAMORPHOSES OF INSECTS. 



The young Cockroach is hatched from the egg in a condition 

 in which it hardly differs from the parent insect. It is simply 

 paler in colour ; its eyes are smaller, with fewer facets ; the wings 

 are not developed, and the reproductive organs are immature. 

 The change from the newly hatched insect to the reproductive 

 adult is simply a question of growth. This is naturally accom- 

 panied by several moults, of which there appear to be seven. 



On the other hand, there are many insects which leave the 

 egg in a condition only very remotely resembling the parent 

 form. There is a vast difference between the " woolly bear " 

 and the " tiger moth,'' into which it is ultimately converted. 

 Moreover, in this case, the transition from larva to adult is not 

 a gradual one. There is an abrupt change ■ from the cater- 

 pillar to the chrysalis, from the chrysalis to , the moth. To 

 these changes the term " metamorphosis " is applied ; and insects 

 which exhibit such metamorphoses are termed " metabolous " 

 to distinguish them from the " ametabolous " cockroach. 

 Among metabolous insects are the neuroptera (dragon-flies), 

 hymenoptera (ants, bees, and wasps), the diptera (two-winged 

 flies), and lepidoptera (butterflies and moths). In order to 

 illustrate the nature of this metamorphosis, we shall select an 

 example from each of the last two classes of insects ; the silk- 

 worm will serve as a type of the lepidoptera, the blow-fly of 

 the diptera. 



The life-history of the Silk-worm {Bombyx mori) is briefly 

 this : From the egg emerges a caterpillar, which feeds upon 

 leaves, and continues to grow until it is immensely larger, but 



