DAHLGREN, THE MALARIA MOSQUITO 



21 



during which the internal changes begun in the larva, which are to result 



in the formation of the adult mosquito, are continued and completed. 



Under the pupa skin a new integument is secreted which 



i i ,• i i • p ,i n t Formation of 



becomes the hnal external covering ot the fly. its the A( jult 



appendages, hairs and scales may he seen fully developed 



in late pupal stages like the one represented in the model as shown in 



Fig. 13. 



When the formation of the mosquito fly is complete, the pupa 



skin bursts along the middle of the back and the adult extricates itself 



from its floating case. At this "critical period," large numbers of mos- 



-TH OR AX- 



wing CASE 



RESPIRATORY FUNNEL 



ABDOMEN 



HEAD 



PADDLES LEGS 



FIG 15. THE FULL-GROWN PUPA. 



Magnification about 12 diameters. 



quitoes perish, because, until their legs and wings are thoroughly hard- 

 ened, a slight gust of wind or a ripple of the water will upset and drown 

 them. This makes it possible to bring about the artificial destruction 

 of a large proportion of the insects, through the simple introduction of 

 tidewater into mosquito-ridden marshes. 



The Adult Mosquito. 



The smallest of the local mosquitoes measures not more than 1.5 mm., 

 while the largest, perhaps, the famous "Jersey mosquito" Size 



(Psorophora ciliata), called "Gallinippers" in the South, attains a length 



