CHAPTER II 



THE FLY-EGG, THE LARVA, AND THE CHRYSALIS 



JOHN RUSKIN described the fly as "the queen of the 

 air." Had he realised her mode of life and the work 

 she does, he would in all probability have altered his 

 opinion of her. The house-fly is more aptly described 

 as the queen of the dung-heap. There is one thing 

 which the fly dislikes more than others it is cleanli- 

 ness ; for, as will be seen from the way in which the 

 house-fly spends her existence, she prefers those places 

 where insanitary conditions abound. The domestic fly 

 belongs to the Order of insects known as Diptera, or 

 two-winged insects. Its metamorphosis is complete ; 

 that is, it passes through the stages of egg, larva or 

 maggot, pupa or chrysalis or cocoon, to reach the per- 

 fect flying insect or iinago which we know so well. In 

 order to understand perfectly the habits of flies, these 

 stages of its metamorphosis must be described. 



The female fly prefers to lay her eggs where her 

 young, when hatched, will thrive. Like the female 

 mosquito, the maternal instinct drives the mother-fly 

 to choose the place where her young will find the most 

 suitable food. And in the case of the fly the place 

 preferred is on or near horse-dung. This is the site 

 of election and this is the reason why flies so commonly 

 swarm in and about stables, loose-boxes, and slaughter- 

 houses. Here the flies feed and breed, and it is here 



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