THE MOSQUITOES OF THE SOUTHEASTERN STATES 25 



fective and imparts little odor to the water. Fire barrels may be 

 treated by adding borax or common salt at the rate of 4 or 5 pounds 

 per 50 gallons of water. This will prevent larval development as 

 long as the strength of the solution is maintained. Tubs and other 

 casual water containers left in the yard should be turned upside 

 down when not in use, and worn-out equipment should be dis- 

 posed of. 



With the yellow-fever mosquito (Aedes aegypti) the smaller water 

 containers, such as old cans, bottles, flower vases, and obstructed 

 eave troughs, are important, and a campaign against this species 

 should begin with a clean-up of yards and vacant lots. During the 

 dengue-fever control work in Florida in 1934 a large proportion of 

 the discarded automobile casings left in the open were found to con- 

 tain water with aegypti larvae, and many breeding places were found 

 in automobile-wrecking yards. Toilet bowls and flush tanks in va- 

 cant nouses and apartments require systematic attention, and col- 

 lections of water in the basements of buildings should not be over- 

 looked. The adults of this species do not fly far, and when they 

 become troublesome at any point the breeding source can usually be 

 found on the premises or nearby. An essential part of any aegypti 

 control program is the frequent and thorough inspection of premises 

 by well-trained men. 



One of the most prolific sources of production for the southern 

 house mosquito (Culex quinquefasciatus) in a city or town is the 

 storm-sewer catch basin, which is designed almost universally with a 

 watertight debris trap below the level of the outlet. The larvae of 

 Aedes aegypti also have been found in these places. In an anti- 

 mosquito program the catch basins are usually oiled periodically 

 with special equipment installed on trucks or motorcycles. Other 

 important sources of mass production of C . quinquefasciatus are open 

 cesspools, badly drained street gutters, and polluted ground pools, 

 especially around city dumps or sewage outlets. Wherever possi- 

 ble these breeding places should be eliminated permanently by drain- 

 age, or the cesspools effectively covered; otherwise they require fre- 

 quent treatments with larvicides. 



Paris green will destroy quinquefasciatus larvae in ditches, shal- 

 low ground pools, and catch basins, although oil is usually preferred, 

 as it deters oviposition. The pyrethrum-extract emulsion, mentioned 

 under the general larvicides, has also been recommended for treat- 

 ment of ground pools and sewage beds. 



SALT-MARSH MOSQUITOES (PRINCIPALLY AEDES SOLLICITANS AND 

 A. TAENIORHYNCHUS) 



The salt-marsh mosquitoes fly extremely long distances. Migra- 

 tory swarms have been observed 40 miles or more from their breed- 

 ing places, although the average length of flight is, of course, much 

 less. Because of their great flight range, local work against these 

 species is of little benefit and control programs are usually under- 

 taken on a county-wide basis. Investigations and control work 

 against the salt-marsh species were begun in New Jersey more than 

 30 years ago, and New Jersey's example has been followed by most 

 of the North Atlantic States. On the South Atlantic and Gulf 

 coasts, except in a few counties, no large-scale operations had been 



