84 



Insects and Disease 



four needles consist of a pair of mandibles which 

 are lance-shaped at the tip and a heavier pair 

 of maxillae, the tips of which are serrate on one 

 edge. 



HOW THE MOSQUITO BITES 



When the female mosquito is feeding on man or 

 any other animal the tip of the labium is placed 

 against the surface and the six needles are thrust 

 into the skin, the labellaa serving as guides. As 

 they are thrust deeper and deeper the labium is 

 bowed back to allow them to enter. As soon as the 

 wound is made the insect pours out through the 

 tube of the hypopharynx some of the secretion from 

 the salivary glands and then begins to suck up 

 the blood through the hollow labrum into the 

 pharynx and on into the stomach. 



The mouth-parts of the male differ in some im- 

 portant respects from those of the female. The 

 hypopharynx is united to the labium, the mandi- 

 bles are wanting and the maxillae are very much 

 reduced so that the insect is unable to pierce the 

 tough skin of animals. The male feeds on the 

 juices of plants as do the females when they can- 

 not get blood. It is not at all necessary for mos- 

 quitoes to have the warm blood of man or other 

 animals. Comparatively few of them ever taste 



