40 ARTHROPODA 



fourteen days and attain a length of a half inch or more. 

 If the eggs are laid in late fall they may not hatch until 

 the next spring. The larva rises to the top of the water 

 at intervals to breathe through a tube projecting from the 

 tail end. This tube extends throughout the body and 

 thereby supplies the tissues with oxygen. 



After three molts the pupa stage is assumed and lasts 

 from two to five days, depending upon the temperature, 



FlG. 15. Three pupae and two larvae of mosquitoes at the surface of the water 

 breathing. Photograph from life, twice natural size. 



during which air is admitted to the body by two earlike 

 organs on the thorax. In the next transformation the 

 adult mosquito emerges from a slit in the back of the pupal 

 skin and is ready in a few minutes to fly. 



Food. In its method of taking food the mosquito 

 differs from the locust, as it has no biting apparatus but a 

 piercing and sucking organ forming the proboscis. The 

 labrum (upper lip) and Idbium (lower lip) form a tube inclos- 

 ing the pair of hairlike mandibles and maxillce in addition 

 to a tubular stylet, the hypopharynx, an outgrowth from 

 the floor of the mouth. The hypopharynx lies against 



