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A dust containing 5 peroent of DDT and copper applied twice at the 
rate of 20 pounds per acre-application gave the highest yield of potatoes 
and caused the highest mortality of insects, inoluding the Colorado po- 
tato beetle, of any material tested (arsenical, Dithane, DN dust plus 
copper, sabadilla plus oopper, and copper-lime dust) •— liunro and Redman 
(270). 
A knapsack sprayer was used to apply a 20-percent DDT spray five 
times on early potatoes and three times on late potatoes* Potato leaf- 
hopper counts varied considerably, but the population was definitely 
lower on the DDT-treated plots than on the check* Potato fleabeetles, 
Colorado potato beetles, blister beetles, and tarnished plant bugs were 
not serious •— Gould ( 184 ) * 
In laboratory tests DDT spray killed adults and young larvae after 
24 to 36 hours* The DDT (Gesarol A-20) was added to water at the rate 
of 0.8 pound in 100 gallons*— Fluke and Pond (157 ) » 
Gesarol A-S dust gave complete oontrol of adults and larvae*— 
Fletcher (155). 
This pest was killed with remarkable ease in the adult and larval 
stages within 24 or 36 hours after dusting with a 5-percent DDT dust. 
From 2 years of experiments, it is evident that while DDT has a consider- 
able residual value on foliage under field conditions, it does not 
possess very long residual properties outdoors as compared with indoors* 
The combination of DDT with 5 peroent of yellow oopper oxide gave some- 
what better oontrol of most of the potato insects than the same concen- 
trations of DDT alone.— Granovsky (187) * 
A DDT aerosol produced excellent kills*— Ditman (133 ) • 
Pari a canella (F.) , -the strawberry rootworn 
In greenhouse tests, 8 ounces of 1SDT per 100 imperial gallons of 
water gave 100 peroent kill of adults both by stomaoh poisoning and by 
contact.— Ross (306 ) ♦ 
In the laboratory a water suspension of 4 pounds of 20-percent DDT 
powder with wetting agent (A-20) per 100 gallons of water was poured on 
a glass plate and allowed to dry* A white film was visible on the plate 
when the spray dried* After 291 days strawberry rootwonas were oaged with 
the plates and clean strawberry leaves* After 4 days all the insects 
were on their backs; after 5 days, all were dead* In a similar test a 
3-percent dust (A-3) was also applied as a thin deposit on a glass plate, 
and insects were caged immediately with the plate and clean strawberry 
leaves. All the insects were dead at the end of '5 days, the speed of 
killing being no greater than that of the aged spray deposit described 
above*— Smith (325)* 
