8 LEAFLET 18 6, IT. S. DEPARTMENT OF AGRICULTURE 



graded streets and alleys and in public buildings and parks. Where 

 well-organized county or city mosquito-control units exist, work of 

 this kind is taken care of by them, and house-to-house inspection 

 also may be carried out with good results. The educational features 

 of such work should be emphasized and the responsibility for preven- 

 tion of breeding placed largely on the occupant of the premises. 



Screening and Bed Nets 



In most communities the screening of houses is essential for protec- 

 tion against mosquitoes, flies, and other insects. The screens should 

 be well fitted. They should be of 16-mesh wire cloth. A few of the 

 small yellow-fever mosquitoes can get through standard 16-mesh 

 wire. This can be avoided by painting the wire lightly with screen 

 enamel, or 18-mesh wire may be used. Screens of bronze, copper, or 

 one of the corrosion-resisting alloys are most durable in humid climates. 

 In dry climates galvanized or painted wire is satisfactory. Full-length 

 window screens are always more satisfactory than half screens or 

 those inserted under the sash. Screen doors should open outward. 

 Mosquitoes often enter houses through chimneys and open fireplaces, 

 and screening these is frequently necessary. Bed nets, if kept mended 

 and tucked under the mattress at the edges, give much protection in 

 unscreened or poorly screened houses. 



Sprays 



When mosquitoes gain access to a house or other building a thorough 

 treatment with an effective household spray is advised. Since these 

 pests may live for weeks and repeatedly attack the inmates of a house, 

 the importance of destroying them is evident. Dangerous malaria- 

 carrying mosquitoes are also destroyed by sprays. An extract of 

 pyrethrum in a highly refined kerosene oil is the material most used 

 in such sprays. The material is applied with a good hand atomizer 

 or with an electric sprayer. The rooms should be closed before being 

 sprayed and kept closed 10 or 15 minutes. The air should be well 

 filled with a fine-spray mist. Since these mosquitoes hide away 

 behind pictures, under furniture, and among clothing in closets, all 

 such hiding places should be reached by the spray. Sprays will also 

 kill mosquitoes on screened porches, but here even more thorough 

 application is necessary, and it is best to sweep up and destroy the 

 paralyzed mosquitoes, as some may revive. 



Repellents 



There is no known substance that will give complete freedom from 

 mosquito attack for more than a few hours. Oil of citronella is probably 

 the most dependable. If oil of citronella is objectionable because of 

 its odor, it can be mixed with spirits of camphor or oil of pennyroyal 

 in equal proportions. Certain cut or growing plants have been 

 reported to drive mosquitoes away, but none of these is of practical 

 value. 



U. S. GOVERNMENT PRINTING OFFICE: 1939 



For sale by the Superintendent of Documents, Washington, D. C. - - - - Price 5 cents 



