-77 - 
percent of chlordane and 80 percent of urea- formaldehyde, nitrocellulose, 
or polymerized diolefins dissolved in a vehicle. The time for knockdown of 
flies placed in the "box was greater for chlordane than for DDT in all three 
coatings. — Block Q6, %0 • 
Flies confined in a small screen-wire cage were exposed for 2-minutes 
in a 100-cubic foot cabinet in which chlordane dissolved in cyclohexanone 
had "been sprayed 30 seconds previously. A 5-percent concentration of chlor- 
dane gave 8 percent knockdown in 30 minutes and 100 percent mortality in 24 
hours. The calculated concentrations giving 90 percent mortality were: 
gamma "benzene hexachloride 0.17; DDT 1.0; chlordane 0.88; and toxaphene 
4.9. In residue tests (10 mg. /sq.ft.) chlordare was superior to DDT in 
kill of flies after 8 weeks. — Gahan e_t al. (l62). 
A mixture of 0.8 percent of Van Dyk 264 [N-(2-ethylhexyl)bicyclo- 
(2.2.1 )-5-heptene-2 t 3-dicarDoximide], 0.2 percent of pyrethrins, and 0.2 
percent of chlordane in Peet-Grady tests gave a 10-minute knockdown of 99 
percent and a 24-hour kill of 98 percent. It requires a concentration of 
2 percent of Van Dyk 264 plus 0.025 percent pyrethrins to give satisfactory 
kill and knockdown of house flies. When 0.2 percent of DDT or chlordane 
was added, the concentration of the compound could he reduced to 1 percent 
and a satisfactory kill and knockdown obtained. — Hartzell ( 207 ). 
Toxicity of insecticides expressed in terms of percent mortality or 
LD-50 may vary greatly in different laboratories and at different seasons 
of the year, even if the same equipment was used. Toxicity index, which is 
used as a relative value to express the toxicity of insecticides, is 
defined as the ratio between the LD-50 of a standard insecticide and the LD- 
50 of the test sample, multiplied by 100. The toxicity of technical chlordane 
to house flies, determined by the tunnel spray method of Eoan and Kearns, 
varied from 154 to 190 (alpha chlordane - 100). The toxicity index of alpha 
chlordane (a stereoisomer of chlordane, m.p. 101-102.5° C.) was 6,^ (diel- 
drin'rr 100) or 12.1 (aldrin = 100).— Sun ( 447 ) 
The effect of temperature on speed of knockdown and mortality of house 
flies exposed to residues of several chlorinated hydrocarbons was deter- 
mined by exposing house flies (l) continuously at constant temperatures of 
70° and 90° F. and (2) for predetermined periods (l to 20 minutes) at 70° 
and 90° and then holding them for 24 hours at the same temperature at which 
they were exposed. At a dosage of 50 mg. per square foot chlordane re- 
quired 100 minutes for knockdown at 70° F. and 63 minutes at 90° F. — 
Hoffman and Lindquist (223). 
A deposit of 144 mg. chlordane per square foot of plywood panel killed 
100 percent of NAIDM house flies exposed for 5 minutes. — Hansens and G-oddin 
(2Q2). 
In 1948 in California a comparison of the chlorinated insecticide for 
fly control in dairy barns showed BHC to be the most satisfactory material 
for the replacement of DDT. Only the barn walls were sprayed - not the 
animals. Chlordane at 50 pounds per 100 gallons of water was slow in knock- 
down, gave an excellent clean-up, and lasted for from 1 to 4 weeks. — Dietz 
(102). 
