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When tested in the form of deposits, chlordane paralyzed roaches 
more quickly than DDT and toxaphenc , "but less quickly than gamma-3EC. — 
Hanman ( 202 ) . 
Residue tests were made by placing the insects on crystalline de- 
posits of the compounds on filter paper, deposited from standard acetone 
solutions. Chlordane and gamma "benzene hexachloride were about equal in 
toxicity and each was more than 1,000 times as toxic as DDT. A chlordane 
residue of 1.3 micrograms per square centimeter killed 70 percent of the 
roaches inl20 hours. — Metcalf ( 3 , 2,3 ) . 
Adult German and American cockroaches were placed for two hours on 
pieces of cotton twill cloth that had been impregnated with acetone solu- 
tion of the test material at the rate of 200 mg. per square foot. Gamma 
benzene hexachloride was the best of the materials during the first week 
and was outstanding on 5-hour knockdown, but it had lost most of its 
toxicity by the 28th day. Chlordane was effective when fresh and was 
somewhat more lasting than the other materials, although it was not 
highly effective after 28 days. DDT and toxaphene did not give high 
kills from 2-hour exposures even when freshly applied. The American 
cockroach appeared to be somewhat more resistant than the German cock- 
roach to gamma benzene hexachloride and chlordane, but showed less re- 
sistance to DDT. Chlordane and gamma benzene hexachloride sprayed at the 
rate of 100 mg. per square foot on the walls of kitchens infested with 
cockroaches (chiefly Blattella germanica with P. americana ) eliminated 
a high proportion of the roaches, and the rooms did not become reinfested 
with this species during the subsequent observation period of 8 weeks. 
Solutions of chlordane and a mixture of chlordane and DDT, when dispersed 
by means of a thermal fog generator, effectively controlled cockroaches, 
but a similar treatment with DDT alone was much less successful.— Gahan 
et al. (162). 
Chlordane should be applied at about 500 mg. per square foot. The 
apparent greater effectiveness of chlordane over DDT may be due to the 
persistent sticky nature of the material coupled with a slight fumigating 
property. — Kruse ( 269 ) . 
In laboratory tests chlordane at 2-percent strength in oil solution 
was more effective than a 10-percent DDT powder .--Gould ( 183 . 18U . 189). 
Five gallons of a 2-percent chlordane emulsion applied with a Ses- 
Kil aerosol generator to a building gave practically 100 percent control, 
and only a few roaches had reappeared k months later. — Sorasen and Munro 
too). 
Perlplaneta a mericana (L.), the American cockroach 
The relative toxicity of chlordane and DDT to the American roach was 
determined by applying precisely measured dosages to the thoracic territes. 
Dosage mortality curves plotted from data obtained in these tests showed 
chlordane to be approximately three times as toxic as DrT to this insect. 
The LD-50 for chlordane was found to be approximately Ik micrograms per 
