108 DIPT ERA. 



able for being an apterous insect, wanting the 

 wings with which the others are provided. 

 Birds are also subject to the visitations of this 

 genus, and they are to be found between the 

 feathers of the swallow, the sparrow, and others 

 of the smaller kinds. 



There is a singularity attending the genera- 

 tion of the Hippoboscae, which is highly de- 

 serving of notice. Other winged insects pass 

 from the egg to the caterpillar, or maggot, then 

 to the chrysalis, and lastly to the perfect fly. I 

 But the Hippobosca has a shorter way of com- j 

 pleting its purpose. The female lays an egg 

 of a size which excites astonishment, since it 

 equals, if it does not exceed, that of the abdo- I 

 men from whence it proceeds. This egg may ] 

 be considered as a chrysalis, undergoing no j 

 further alteration, except changing in colour, 

 from a brown to a deep shining black, till the 

 fly ready formed for action issues from the shell. 



The different species of this genus are very j 

 tenacious of life, and most of them have so 

 firm and coriaceous a skin, that a moderate de- I 

 gvce of pressure has no effect upon them. 



