MOSQUITOES 475 



creatures called wigglers. The most noticeable things about a 

 wiggler are that a tube projects from its body near the posterior 

 end and that the wiggler frequently thrusts this tube out of the 

 water and hangs suspended head down from the surface of the 

 water. The tube is a breathing organ and is thrust out of the 

 water for air. As soon as a wiggler has a supply of air, it is 

 free to move through the water; when the supply is exhausted, 

 the wiggler returns to the surface for more. 



The young wigglers feed greedily on living things which they 

 find in the water and grow rapidly, molting their skins several 

 times. After a week they change into a totally different form, 

 the pupa, very much as the fly does. The pupa of a mosquito 

 is characterized by two projections in the upper and forward 

 end of the body. These are breathing tubes and project out 

 of the water most of the time. In three days the skin of the 

 pupa bursts, and an adult mosquito works its way out. It 

 floats on the skin until its wings are dried by the air; then it 

 flies away. If the adult mosquito is a male, it leads a harm- 

 less life, feeding on the juices of plants or doing without food, 

 if it is a female, it pierces the skin of man and other animals 

 and lives on their blood, causing great annoyance and spreading 

 disease. 



Since mosquitoes lay their eggs only in quiet waters, such 

 as ponds, pools, and marshy lands, if ponds, pools, and marshes 

 are drained or filled up, the mosquitoes lose their breeding 

 places and die without reproducing. If it is not possible to 

 drain the land or to fill it up, oil can be used to destroy the 

 breeding places. A thin layer of oil on water smothers the 

 wigglers which are already there because they cannot pierce 

 through the oil and secure air; it kills all eggs which are on 

 the water, and it also kills all mosquitoes which touch it in 

 their attempt to lay eggs beneath it. The thinnest film of 

 oil is sufficient to destroy mosquitoes, and very little is needed 



