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Scolytidae 
Hylastinus obscurus (Marsh.), the clover root boier 
A 5-percent chlordane dust, applied at the rate of 2.5 pounds of toxi- 
cant per acre in May 1947 in Hew York, rave excellent control and a 1-per- 
cent chlordane dust at 2.25 pounds of toxicant per acre gave high control. 
Uone of the insecticides tested as sprays at the rate of 1 pound of toxi- 
cant oer acre were satisfactory. Chlordane did not injury red clover. — 
Marshall et al. (314). 
Chlordane dust at the rate of 2 pounds toxicant per acre gave 46.6 
percent non-infested plants as compared to 30 percent in the untreated 
check. The clover hay at harvest time "bore a chlordane residue of 2 p.o.m. 
Aldrin, dieldrin, and BHC gave the "best (90 percent or "better) controls. — 
Gyrisco and Marshall ( 199 ). 
Tenehrionidae 
Tribolium castaneum (Host.), the red flour "beetle 
Portions of insecticidal dusts, judged to "be "between 50 and 100 mg., 
were applied to counted groups of T. castaneum in 2x1 in. specimen tubes. 
The tubes were gently shaken to distribute the dust and were then stored 
under controlled conditions of temperature and humidity until the insects 
were inspected. The results show that a relatively small increase in con- 
centration of poison in a dust results in a large increase in mortality. 
Frequently, a fourfold increase in concentration has resulted in a change 
from a very low to very high mortality. A 0.1 percent chlordane dust 
killed 99 percent of the beetles in 24 hours at a temperature of 75° F. 
and a relative humidity of 70 percent. Chlordane was about 5 times more 
toxic than toxaphene. — Lord ( 3 , . 2 ) . 
Tribolium confusum Duv., the confused flour beetle 
Larvae are more resistant than the adults to spray residues. Eg's 
and pupae of the confused flour beetle do not appear to be materially 
affected by exposure on surfaces that have been sprayed with residual 
sprays. Immature stages were exposed for 24 hours to deposits of DDT, chlor- 
dane, and gamma benzene hexachloride that had been applied to glass plates 
at the rate of 50 mg. per 1/4 square foot. Eggs hatched almost normally, 
the average percentage being 77 after exposure to DDT, 75 for chlordane, 
and 47 for gamna benzene hexachloride, as compared with 77 percent for ' 
check. A residue of 200 mg. chlordane per square foot on a glass plate 
killed 100 percent of the adult beetles ej.rosed to it for 24 hours in 18 
days. The effectiveness of residual sprays decreased with the increase in 
the absorptiveness of the surface sprayed. Their effectiveness also rarle 
vrith the chemical composition of tke surface. On cement surfaces the dur.. 
tion of effectiveness of all spray deposits was very short. Pretreatr.ent 
of cement with a sealer, magnesium-zinc-silicofluoride , ^d 
