96 



THE REPORi' OF THE 



No. 19 



water. The tension of tlie surface film buoys up the rosette, and hence the wriggler itself. 

 Through this breathing tube the insect, gets its supply of air [Find out how long a wriggler 

 (3*n remain under water without coming to the surface for air.] 



In nine or ten days, the wriggler assumes another shape — known as the pupa. [Determine 

 ihow often the wriggler moults in this time.] 



The Pujyr. They are considerably different in appearance from the true wrigglers. Their 

 5iead-end is much enlarged (Fig. 53) and the insect is somewhat club-shaped. There is a differ- 

 sence also in their appearance when at rest. The head-end is at the surface, and the supply of 

 air is taken in by two breathing tubes attached to the upper surface of the thorax i^ortion of the 

 enlarged end. Unlike most pup;e, the pup;e of the mosquitoes are active creatures, wriggling 

 about in the water. 



Fig. 5i.—Culea: jmngens : Female above, male below,— enlarged. Scales on margin of wing ; 

 scales along veins of wing. (From Howard, U. S. Department of Agriculture.) 



When a pupa-wriggler is disturbed, it becomes apparent that it makes greater exertions 

 sinking than it does in rising. Its body, then, is lighter than water, and rests naturally at the 

 surface without the aid of a special float. 



During this stage, the mosquito develops the wings, legs, and the peculiar stmging mouth- 

 Tparts, which are of such value to it in the adult stage. The rudiments of the wings and legs 

 may be seen through the pupa-case, if a strong magnifying glass be used. In two or three days, 

 the adult winged mosquito escapes from the pupa-case. (Fig. 64.) 



The Adult Mosquitoes. When the time arrives for the emergence of the winged mosquito, 

 the pupa-skin splits along the back, and the insect gradually raises itself on its long spmdly 

 egs using the old pupa-skin aa a raft. It is nearly bent double as it pulls its wings out, but soon 



