INSECTS D1PTERA DIAGRAM C. 143 



ORDER DIPTERA. 



This order may be known immediately by the insects which 

 compose it having but two wings; they have also no jaws, but 

 only a proboscis or a sucker. 



The Gnats and Mosquitoes live near water, and lay their eggs on 

 its surface ; the eggs are joined together in] regularly shaped 

 masses, and resemble a little boat floating on the water. The 

 larvjfc are aquatic, and swim by jerks by doubling themselves up. 

 They rise to the surface with their head downwards. They 

 breathe by the extremity of the body, where the trachese open. 

 The pupae are also aquatic, and swim by jerks, but may be known 



Gnat magnified. Gnat. Larva of Gnat 



magnified. 



by a kind of horns near the head. In their perfect state, the 

 gnats fly chiefly in the evening, and light upon men and animals 

 to suck their blood ; they bury their sucker rapidly under the 

 skin, and the wound which they make remains painful for some 

 time, on account of the venom discharged into it. The shrill 

 noise which gnats, and especially mosquitoes make when flying, is 

 caused by the rapid motion of their wings, which strike the air 

 several thousands of times in a minute. 



