THE MOSQUITO. 17 



Note that as they lie at the surface it is not the posterior tip of the 

 body which touches the water, but the back or upper part of the 

 bulbous head end. How do they breathe then ? By means ot 

 two horn-like, hollow processes that project from the back of the 

 head end. In this they differ from the wriggler, and we shall see 

 later that they differ in many other details. As they do not feed 

 there is no special need of having the breathing apparatus at one 

 end of the body and the feeding apparatus at the other, or that 

 the head should hang down in the water while the insect is breath- 

 ing. But is there any special advantage in having the pupa float 

 at the surface with the back of the large head end of the body up- 

 permost ? There is, indeed; it is more than an advantage; it is al- 

 most a necessity. It is from the pupa that the winged mosquito 

 comes. Now the delicate wings of the mosquito are folded up in 

 pads (which we shall later study) on the pupa. These wing pads 

 are attached to the upper part or back of the big head end of the 

 pupa, and when the mosquito is ready to emerge, this back of the 

 big head end of the pupa, which is at the surface of the water 

 splits longitudinally and the back ot the mosquito with the deli- 

 cate wings slips quickly out and above the surface of the water, 

 without getting wetted. The delicate wings are immediately un- 

 folded and in a moment or two the mosquito is ready to fly away. 

 If the wings were drawn out of the pupal sheath in the water it 

 is probable that few mosquitoes would ever be able to fly. Thus, 

 you see, the second young stage of the mosquito, the pupa, altho 

 verj' difi^erent from the first stage, the larva, is also admirably 

 arranged for the successful living of the mosquito. 



I have constantly referred to these strange wriggling creatures 

 inhabiting foul water as young mosquitoes. But they do not at 

 all look like mosquitoes; they live in water, not in air; their habits 

 are very difl^erent from those of the mosquito. How do I know, 

 how do you know, that these curious wrigglers are young 

 mosquitoes? Simply and sufiiciently by watching one of these 

 creatures thru its life. 



