CHAPTER IV 



DEVELOPMENT OF THE PUPA AND FLY WITHIN 

 THE LARVA 



General In Cliironomus the fly differs so conspicuously from 



explana- . „ , 



tiona. the larva that, without direct observation oi the passage 



of the one into the other, no naturalist could have guessed 

 that they were in any way related. In certain insects 

 the transition from the creeping to the flying stage is 

 mainly effected by small additions and modifications, 

 which take place beneath the skin, and only become 

 apparent at times of moult. Thus in a locust the wings, 

 crumpled up within their sheaths, become longer and 

 longer every time the skin is cast. While the wings 

 are being perfected by definite, though not very con- 

 spicuous steps, the reproductive organs steadily increase 

 in bulk and complexity, and at length the adult structure 

 is attained without any sudden alteration of form, any 

 change of food, or any resting-stage. 



In most insects the larval stage is a time of voracious 

 feeding, while the winged fly either does not feed at all, 

 or feeds u]Don food which can be quickly taken into the 

 body, and which does not materially hinder flight. 

 A radical change of mouth-parts thus becomes necessary, 

 and such a change involves a resting-stage. It is 

 popularly believed that during the resting-stage the 

 new mouth-parts, the compound eyes, the long antennae, 

 the long legs, and the wings, all of which characterize 



