400 



Handbook of Nature-Study 



' ! \X . 



THE MOSQUITO 



Teacher's Story 



N DEFIANCE of the adage, the mother of our most 

 common mosquitoes does not hesitate to put her 

 eggs all in one basket, but perhaps she knows it is 

 about the safest little basket for eggs in this world 

 of uncertainties. If it were possible to begin this 

 lesson with the little boat-shaped egg baskets, I 

 should advise it. They may be found in almost 

 any rain barrel, and the eggs look like a lot of tiny 

 cartridges set side by side, points up, and lashed 

 or glued together, so there shall be no spilling. 

 Like a certain famous soap, they "float," coming up 

 as dry as varnished corks when water is poured upon them. 



The young mosquito, or wrig- 

 gler, breaks through the shell of 

 the lower end of the egg and 

 passes down into the water, and 

 from the first, it is a most in- 

 teresting creature to view 

 through a hand lens. The head 

 and the thorax arc rather large The egg-raft of a mosquito enlarged. 



while the body is tapering and 



armed with bunches of hairs. At the rear of the body arc two tubes very 

 different in shape; one is long, straight and unadorned; this is the 

 breathing tube through which air passes to the trachea- of the body. 

 This tube has a star-shaped valve at the tip, which can be opened and 

 shut; when it is opened at the surface of the water, it keeps the 

 little creature afloat and meanwhile allows air to pass into the body. 

 When the wriggler is thus hanging at an angle of 45 degrees to the 

 surface of the water, it feeds upon small particles of decaying vegeta- 

 tion; it has a remarkable pair of jaws w r hich 

 are armed with brushes, which in our 

 common species, by moving rapidly, set up 

 currents and bring the food to the mouth. This 

 process can be seen plainly with a lens. 

 When disturbed, the wriggler shuts the valve to 

 its breathing tube', and sinks. However, it is 

 not much heavier than the water; I have often 

 seen one rise for some distance without apparent 

 effort. The other tube at the end of the body, 

 supports the swimming organs, which consist of 

 four linger-like processes and various bunches of 

 hairs. When swimming, the wriggler goes tail 

 first, the swimming organs seeming to take 

 hold of the water and to pull the creature back- 

 ward, in a series of spasmodic jerks; in fact, 

 I he insect seems simply to "throw somer- 

 saults," like an acrobat. I have often observed 

 wrigglers standing on their heads in the 

 bottom of the aquarium, with their jaws bent 



A mosquito aquarium. 



