134 



INSECT LIFE. 



general form of the pupse is shown at b in Fig. io8. 

 Usually larvae and pupas are found at the same 

 time, but if you have only larvae you can obtain 

 pupae by keeping the larvae in water till they trans- 

 form. 



1. Note and describe the differences between the 

 larvae and the pupas in the following respects : The 

 form of the body. The position of the insect when 

 at rest. The number and position of the breathing- 

 tubes. (The structure of a breathing-tube of a pupa, 

 as seen through a microscope, is shown at b in Fig. 

 109.) 



2. Note that the pupse of mosquitoes are active, 

 swimming with a wriggling motion similar to that 

 of the larvae. It is a very unusual thing for insects 

 that have a complete metamorphosis (see page 35) to 

 be active in the pupa state. 



3. Observe the wing-pads on the sides of the 

 thorax, also the leaflike appendages at the tail end of 

 the body, with which the insect swims. 



4. If you have an opportunity to do so, study the 

 pupa with a microscope and make a large, detailed 

 drawing of it. 



5. How does the pupa make use of the surface 

 film of water ? 



The Emergence of Mosquitoes. — The pupa 

 state of mosquitoes lasts only a few days, then the 

 skin splits down the back, and the winged mosquito 

 carefully works itself out and cautiously balances 

 itself on the cast skin, using it as a raft, until its 

 wings are hardened so that it can fly away. 



Collect many wrigglers, and, keeping them in 

 water, try to observe the emergence of the adult. 



