INSECTS OF THE HOUSEHOLD 65 



stages, known as " wrigglers," in the water, and in from 

 seven to fourteen days, according to weather, emerge as 

 adult mosquitoes. A female may lay from 200 to 400 

 eggs. A good example in arithmetic is the following: 



Suppose a mosquito lays 200 eggs, one-half of which 

 hatch females, and these each lay 200 eggs, and so on, 

 calling the time for a generation ten days ; how many 

 mosquitoes would there be after 180 days, i.e., in the 



FIG. 21. FEMALE MOSQUITO 



eighteenth generation? The answer is 2,000,000,000,000,- 

 000,000,000,000,000,000,000,000,000, one-half of which 

 may be males. 



In one month a single female mosquito may thus give 

 rise to from 1,010,100 to 2,020,000 female mosquitoes, 

 quite enough to stock a good-sized city. 



Lessons on mosquitoes may be undertaken at any sea- 

 son of the year, but are especially valuable after warm 

 weather begins in spring, April or May for most parts 

 of this country. A lesson or two in winter will prove 

 instructive in discovering how mosquitoes pass this sea- 

 son. The children should then be asked to seek for 

 specimens in stable and house cellars. 



