6o 



GENERAL SCIENCE 



warfare upon flies requires preventive measures. From the 

 earliest springtime, large outdoor flytraps should be kept 

 about garbage cans, in stables, and near the outer doors of 

 kitchens or wherever else food is being prepared or served. 



The eggs of the common mosquito are found floating in 

 stagnant water. Under favorable conditions these may hatch 



W 



FIG. 25. Life history of the mosquito. i, eggs; 2, larva; 3, pupa; 

 4, the common mosquito (Culex). WW, water level below which larva 

 and pupa almost wholly float. This makes possible" their suffocation with a 

 thin layer of crude petroleum spread over the water surface. 



within one day. The larvae (known as wrigglers) after 

 about a week of rapid growth enter a pupa stage. This 

 state continues but a few days when the change to a fully 

 developed mosquito occurs. In waters stocked with fish, 

 these wrigglers are devoured.in large numbers. Where water 

 surfaces of stagnant pools in marshes are covered with a 



