-130- 
and out -with a 2«5-percent solution of DDT in kerosene, but in both 
cases the tests were interrupted after a short time. In one house 
no sand flies were seen or reported 4 and 8 days after the spraying; 
in the other house, no sand flies were seen or no bites reoeived for 
4 or 5 days.— Gorgas Memorial Laboratory (182 ) « 
Culicidae 
Aedes aegypti (L.), the yellow-fever mosquito 
Pieces of filter paper were treated with a range of doses of pure 
DDT, in a volatile solvent, so that the surface presented to test insects 
was dry; all insects were exposed at the same temperature and for the 
same period. The lethal dose for Aedes aegypti was 0,001 rng. of pure 
DDT per square centimeter,— Buxton (10*0") T~ 
DDT is promising for mosquitoes.— Annand (74), 
Gammexane £benzene hexachloride] scattered at the rate of 1/2 pound 
per acre killed 97 percent of the larvae in 2 days and 100 peroent in 
3 days, as compared with kills of 43 percent in 2 days and 97 percent in 
3 days with the same amount of DDT.— Anon. (52), 
Aedes sollioitans (Wlk.), the salt-marsh mosquito 
Under laboratory conditions colloidal solutions of DDT show very 
high toxioity to larvae of A. sollioitans and Culex pipiens L. but low 
toxicity to pupae of the same species. The toxicity to pupae can be 
materially increased by incorporating DDT into a mosquito oil emulsion. 
In dust form DDT proved ineffective against pupae and of considerably 
lower toxioity to larvae of subsurface-feeding species than it did in 
either an oil emulsion or colloidal solution. Toxicity to larvae can be 
increased by the use of certain solvents for incorporating the DDT into 
the dust. Under field conditions DDT dusts were practically ineffective 
against pupae, only of moderate toxicity to larvae of sub surf ace- feeding 
species, but highly toxic to larvae of surface-feeding species. As an 
oil emulsion, DDT gave effective control of both larvae and pupae in 
certain breeding places and poor control in other places, especially 
where pollution was present,— Ginsburg (178). 
Dilutions of 1 part DDT to 50,000,000 parts of water were very 
toxic to larvae of Aedes soliicitans and Culex pipiens in the labora- 
tory. Toxicity to pupae of 1 the same species was low. In the field, 
DDT preparations usually did not last any longer than mosquito oil 
applied under similar conditions, and were even less effective against 
pupae than in the laboratory. However, DDT preparations were more effec- 
tive against anopheline larvae than against subsurface-feeding larvae. 
Baulsion 50-D, applied at the rate of 50 to 70 gallons per aore, gave 
100 peroent kill of anopheline larvae and lasted for 8 days. In general. 
