MOSQUITOES, SILKIVORMS, AND DRAGON-FLIES 7 



its posterior tip. What are the dorsal tubes for ? With 

 what do they correspond in the larvae ? The pupa takes 

 no food at all, and usually floats quietly at the surface. 

 Why then does it swim at all .'' What is the use of the 

 flaps at the end of the body 1 Note the indications of 

 legs and wings folded on the under side of the head 

 end. Make a drawing showing and naming these 

 parts. 



In two or three days the pupa suddenly changes into 

 the full-fledged winged mosquito. That is, the cuticle or 

 outer skin wall of the body splits along the middle line of 

 the back, and the winged mosquito emerges through this 

 opening. What part of the body appears first 1 What 

 parts next .'' While the mosquito is emerging the pupal 

 skin serves as a raft upon which the soft-bodied damp 

 insect is partly supported until its wings and legs are un- 

 folded and dried and hardened, and it is ready to fly 

 away. Sometimes the body rests simply on the surface 

 of the water, being supported by the surface film. This 

 transformation of pupa into fully developed mosquito can 

 be readily observed, and each pupil should see it. 



The winged or imago stage. — The mosquito is now 

 full-grown and fully developed ; and in this fully devel- 

 oped stage it is called an imago, to distinguish it from 

 larva and pupa. It is of course the same insect, a mos- 

 quito all the time, but we commonly apply that name 

 only to the winged stage or imago. A few of the winged 

 mosquitoes should be killed in a " killing-bottle " (see 

 page 335), and examined under a hand lens. Two kinds 

 may be distinguished; one with many long hairs on their 

 feelers or antenna;, the other with fewer and much 

 shorter hairs ; the latter are females, the ones with bushy 

 antennae males. These antennje are the mosquito's 

 organs of hearing. How many wings has the mosquito } 

 How many pairs of legs > Can you find behind the 



