- 72 - 
Aedes spp. 
Tests were made against Aedes mosquito larvae on 1*4-6 one-eighth to 
one-half-acre plots near Anchorage, Sklutna, and Gulkana, Alaska. Nine- 
teen tests were also made against Cullseta larvae. DDT oil solutions 
were mora effective than fuel-oil solutions of chlordane. Against 
Cullseta larvae DDT, in fuel-oil and in water emulsions, was superior to 
fuel-oi}. solutions of chlordane. Five-percent chlordane in fuel-oil at 
0.2 pound toxicant per acre killed 62 percent of Aedes larvae in 48 hours; 
the same dosage of DDT killed 98 percent. — G-jullin e_t al. ( 178 ). 
Studies were conducted at Ft. Churchill, Manitoba, Canada in 1947 and 
1948 to compare the effectiveness of new insecticides against arctic species 
of Aedes mosquito larvae. Chlordane was less toxic in oil solutions than 
DDT, but gave comparable kills as emulsions at a dosage of 0.1 pound per 
acre. None of the materials at the dosages tested was effective against 
pupae.— McDuf fie et al. (308). 
Anp-pheles crucians Wied. 
Sane as for £. quadr imaculatus in residue tests in "buildings. — G-ahan 
et a.\. ( 162) . 
Anopheles quadr imaculatus Say, the common malaria mosquito 
The residual toxicity of chlordane, DDT, and gamma "benzene hexachloride 
was compared "by applying emulsified xylene solutions of the compounds to the 
surface of wallboards, which were then exposed at intervals over a period 
of l6 weeks to adult Anooheles quadr imaculatu s. The increase in time re- 
quired to produce a 100-percent knockdown as the treated surfaces aged was 
used as an index of loss in effectiveness of the compounds, by volatiliza- 
tion, absorption, or other means. After l6 weeks of aging, the time re- 
quired for ganma benzene hexachloride treatment to produce a 100-percent 
knockdown had increased by a factor of 10 over its initial knockdown time. 
In the same period the time required for the chlordane treatment to pro- 
duce a 100-percent knockdown had increased by a factor of 3, whereas, that 
of DDT remained approximately constant. It would seen that of the three 
materials DDT will provide the most permanent toxic surface. It is believed 
that the loss in residual effect from chlordane and gamma benzene hexa- 
chloride is due to their greater volatility, the latter being the more 
volatile of the two. Preliminary volatility measurements indicate chlor- 
dane to be considerably more volatile than DDT. A series of tests made 
to compare the larvicidal properties of chlordane, DDT, and rai^ft benzene 
hexachloride to the larvae of Anoohele s quadr imaculatus resulted in the 
conclusion that there was no significant difference in the t :-is 
when applied as acetone suspensions, emulsions, and dusts. — Hearns e_t al . 
(245). ' 
At the Orlando, Florida laboratory of the Bureau of Entomology and. 
Plant Quarantine it was found that the toxicity of chlordane war- ' ically 
identioal with that of DDT to larvae of the malaria mosquito (0.01 p.p.m. 
killed 98.3 percent in each case in 48 hours). — Bishopp (J2) ; Knipling 
