- 2 6-. 
-These, tests were made in the laboratory on fourth instars. Later this 
author reported that of. 17 fourth instars ' treated with 'derris root 5 
died. at the following molt and 3 more could hot build complete pupal 
cases, Of the 9 normally' pupated caterpillars, 6 developed into female 
moths and the other 3 died in the pupal cases. 
Malacosoma americana (F.), the eastern tent caterpillar 
Mclndoo, Sievers, and Abbott (264.) in 1919 reported the results of 
tests with derris against young caterpillars' of this species in a 
series c " strengths ranging from 1 pound of powder per 8 gallons of 
water to 1 pound per 200 gallons. All the mixtures were 'effective. 
Apple-tree branches -were thoroughly sprayed, and' after the foliage had 
dried 20 to 4-0 ■ newly hatched larvae, were, placed on each branch. The 
larvae began to show signs of discomfort within' 48 hours and practically 
all were dead in from 5. to 10 days. No appreciable feeding was obser- 
ved. In a second series of tests the larvae were placed on -the branches 
and sprayed after they had begun to form their tents. Sprays contain- 
ing 1 pound of powder to '50 gallons of water and 1 pound to 100 gall- 
ons killed all the larvae within 24- hours. When 1 pound to 200 gall- 
ons and 1 pound to 400 gallons were used, not all the larvae were 
killed within 11 days, but the few remaining alive ^ r ere very small and 
inactive. Used as. a dust, this material killed all the treated larvae 
within 1 week. 
Kelsall et al. ( 233 ) in 1926 reported (l) that the derris applied 
to the caterpillars along with the foliage gave much higher control 
than where applied to the foliage alone; (2) that 1 pound of derris 
pe~ 100 imperial gallons of water gave an equal eventual control, 
though much more rapidly, than 2 pounds of le^d arsenate; (3) that 
when applied direct to the foliage but not to the caterpillars, derris 
was not quite equal, pound for pound, to lead arsenate; and (4) that 
used in practical strengths, derris was much more effective than 
nicotine. 
Rotenone suspended in water 1:30,000 killed 100 percent of the 
first and second instars on plum and apple. Of the thirs instars 
47 percent were killed at 1:100, 000— Davidson (90) in 1930. 
Li otle ( 254- 4 255 ) in 1931 reported on the insecticidal properties 
of root' of devil' s-shoestrings ( Tephrosia virginiana ) dug fro^i several 
localities at various times of " the year' and dried by different methods, 
then finely ground in anherb mill.. Field experiments showed tlhat the 
plant has considerable promise as" a' contact spray against this species. 
He also determined the comparative death rates caused by Tephr »osia, 
virginiana root and by derris in experiments with this insect. 
Caterpillars ranging from one-third to two-thirds grown were d.lpped 
in dilutions of 1:400 for 20 seconds and then placed in ca£es on 
dipped, foliage. Fifty caterpillars were used in each experiment, and 
with each, insecticide 4 experiments were run. All the larvae "were 
affected, but some recovered and resumed feeding. . Two experiments with 
each insecticide w.ere carried through until the caterpillars hand either 
died or transformed to moths. From 100 caterpillars dipped 'in the 
derris spray, 14 pupated and Jl moths, emerged, with 3'8 : pupating and 34 
moths emerging from the experiments with devil' s-shpe strings. Field 
