-35- 
hours the great majority were either dead or moved only reebly w^ien dis- 
turbed. Grasshoppers were highly susceptible to DDT in dusts, sprays, 
and aerosols. Twenty pounds per aore of 15 percent of DDT in pyro- 
phyllite applied eithej? as a dust or spray reduced heavy infestations 
of grasshoppers to noneconomio numbers without injury to foliage. Un- 
less washed off by heavy rains, DDT applied as a spray continued to 
kill over a period of several weeks, and in this respeot was more 
effective than dust, which was removed by either wind or rain. Both 
sprays and dusts exhibited marked repellent effect. Sprayed or dusted 
plots of l/2 acre or more, on whioh grasshoppers had been reckiced to 
several per square yard, remained very lightly infested for several 
weeks although surrounded by infestations of 10 to 25 grasshoppers per 
square yard. No traoe of foliage injury from DDT was noted at any of 
the dosages used. Fair to good mortality of grasshoppers was obtained 
from a single application, at the rate of about 20 pounds per acre, of 
a bait mixture containing the following proportions t 3 pounds of 
powdered technical DDT, 100 pounds of wheat bran, 1 gallon of molasses, 
and 1-1/2 gallons of water.— Parker (286 ) 1 Packard (285) . 
DDT, at the rate of 16 ounces in acetone solution dispersed with 
soap per 100 imperial gallons of water, apparently had little effect 
either as a contact or a stomach poison in a test at Vernon, B. C — 
Ross (306 ) • 
Unidentified grasshoppers 
A 10 percent DDT-pyrophyllite dust reduced the population of grass- 
hoppers in an alfalfa field.— Li eberman (245 ). 
A 1 percent DDT-kaolin dust proved ineffective against grasshoppers. 
—Sen (311). 
Blattidae 
Blatta orien tali s L., the oriental cockroach 
DDT is a contact poison.«— Domenjoz (135). 
Blattella germanica (L.), the German cockroach 
DDT was tested in October and November, 1943, and found to give good 
results at dilutions of 10 and 25 percent. In 1944 two commercial mix- 
tures, Gesarol A3 with 3 percent of DDT and Gesarol A20, a spray material 
in powdered form, with 20 percent of DDT, were tested. The 20-percent 
mixture gave good results, whereas the 3-percent material was not satis- 
