THE MUSCIDM. 



403 



describe them, but it must be observed that they do not moult or 

 change their skin during their growth, and that when the time for 

 metamorphosis is at hand, the body shortens, the skin becomes 

 hard, and of a brown colour, and the chrysalis or pupa forms within. 

 Many of the larva live as parasites within other insects. 



In the accompanying engraving the larva of Gymnosoma rotun- 

 data is shown within the body of one of the Hcmiptcra. It has a 

 long hooked-shaped tube, which is attached to its last segment. 



THE METAMORPHOSES OF Gymiiosoina rotnnddta. 



and this tube is protruded through one of the spiracles or respi- 

 ratory orifices of its victim, so that it eats the juices and fat, and 

 breathes through the body of the creature or " host " upon which 

 it is parasitic. The perfect insect and the pupa are also depicted. 



The Flesh Fly and the Blue Bottle are very useful as larvcX, 

 or, as they are called. Gentles, for they devour dead bodies of 

 all kmds, and many species, belonging to the genus Sarcophaga, 

 live upon stercoraceous matter. 



The curious legless larvae are very well known, and so are 

 the egg-shaped, dark-brown pupcX^ The larvae, which at first 



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