88 4 PARKS 



and water that is alkaline will deprive it of a great part of its toxic power. 



Destruction of harboring places. Destroying high grass, weeds and 

 shrubbery close to picnic grounds, camps and other places where people 

 congregate in parks, especially wild parks, will sometimes reduce the nui- 

 sance of mosquitoes, since they use these places for protection against the 

 sun, rain and wind. Unscreened buildings are especially desirable places for 

 harboring mosquitoes, as they spend their daylight hours in dark corners, 

 on ceilings or under floors, and come forth in search of blood at dusk. Such 

 places may be sprayed with a mixture of creosote, using about two gallons 

 to a room. 



Screening. The malaria mosquito bites only at night; therefore, if 

 everyone in a camp slept in a cabin or tent so well screened that no mos- 

 quito could enter there would be little danger of getting malaria. No place 

 is well protected that has twelve-mesh screens, as some mosquitoes are sure 

 to get through. Only sixteen-mesh should be used if complete protection 

 is expected. Screens should be kept in repair, frames should fit well, and 

 cracks under doors and windows closed by some effective method. To 

 prevent the entrance of mosquitoes through chimneys the top should be 

 screened or the fireplace openings sealed. 



Flies. 



Flies are likely to become a special source of annoyance and a menace 

 to health at picnic grounds, refreshment stands, restaurants and in all 

 kinds of camps, although they may be troublesome in other places in parks, 

 especially if in the vicinity of places where food is being served or where 

 breeding places are found. 



"There are in general four species of flies that infest human habita- 

 tions. These are: (i) The blue-bottle fly or 'blowfly'; (2) the green-bottle 

 fly; (3) the common house fly; and (4) a fly similar in appearance to the 

 house fly, but smaller. Flies like mosquitoes pass through different stages 

 of development from the egg to maturity. The female lays her eggs in 

 warm, moist manure or in garbage piles, or in privy contents, where they 

 hatch into small maggots in eight to forty-eight hours. During the next 

 four or five days the maggots eat voraciously and develop a growth of 

 about half an inch. At the end of this period they emerge as full-grown 

 flies." 1 



Measures for the eradication or control of flies consist of the elimina- 

 tion of breeding places, destruction of the adult fly and preventing the 

 access of the fly to the habitations or to the food of man. The house fly 

 breeds habitually in feces, preferably horse manure. Flies can, therefore, 



Sanitation," W. F. Draper and H. B. Hommon, Surgeon General's Office, United States Public 

 Health Service, Washington, D. C. 



