-85- 
Leptlnotarsa decemlineata (Say), the Colorado potato beetle 
In a small-scale test 100 percent mortality resulted when late- 
instar larvae were lightly and evenly coated with Gesarol A-3 dust 
(3 percent DDT), and no feeding was done after the dust was applied. 
In other laboratory tests potato foliage was treated in a bell-jar 
settling chamber and adult potato beetles were added. The treated 
foliage was changed dully. Mortality after 96 hours was 36 percent 
for Neocid No. 10 dust, 34 percent for Gesarol A-3 dust, and zero 
for the check. In a field test on lightly infested potatoes one 
application of Gesarol A-3 dust left «n average of 42 living larvae 
per 46 plants 1 week after application whereas a bordeaux-calcium 
ars«iate spray left an average of 3 larvae per plant.— Ross (306 ). 
A 3-percent DDT dust was effective.— Ha seman (203 ) ♦ 
In the laboratory a 2-percent DDT aqueous spray killed 74 percent of 
adults and larvae in 24 hours.— Hamilton (200). 
Laboratory tests with a 3-percent oust gave 74 percent: oontrol in 
24 hour6»— Okla. Agr. Expt. Sta. (278) . 
Thia insect was controlled when Gesarol A-3 dust was applied at 3- to 
5-week intervals to potatoes.— Parker (287) . 
A 3-percent DOT dust was very effective in controlling larvae and 
adults, and a 1-percent dust, although less effective, was superior to 
other materials. Gesarol Oil Spray SH-5 applied at the rate of 1:200 was 
ineffective. No injury to potato foliage was observed.— Kulash (240 ) . 
The tops of tj^oato seedlings were dipped in suspensions containing 
1 pound of UDT and 4 pounds of lead arsenate per 100 gallons. In one 
series of tests 1 pound of sovbean flour and in another "Orthol K" medium 
summer oil emulsion (1/4 percaot actual oil) per 100 gallons were used 
as a sticker. Both treatments were equal in preventing feeding by the 
potato flea beetle and the Colorado potato beetle. The DDT-soybean flour 
treatment caused moderate yellowing and stunting of plants, whereas the 
DDT-oil treatment caused severe yellowing and stunting. The growth of 
DDT-treated plants was retarded 10 to 14 days when compared with lead 
arsenate-treated plants and untreated check plants. The DDT-treated 
plots yielded 19 tons per acre whereas the calcium arsenate plots yield- 
ed 22 tons.— N. J. Agr. Expt. Sta. (275). 
