-35- 
. Klinger ( 237 ) in 1936 reported that rotenone dust was not effec- 
tive against fourth instars in the laboratory and that rotenone spray 
(0.18 mg. per 500 en, - gave only 10-percent .mortality after 8 days. 
Dorris dust caused 25-pcrcent mortality in 4- days. 
Van der Laan ( 24,4. ) in 1936 reported that this species is sensi- 
tive to derris. 
an anonymous author (5.) in 1937 wrote that for the control of 
this species with derris in the Netherlands a concentration of not 
less than 1 percent of rotenone was necessary, which must be applied 
on a dry day at the end of april or the beginning of May. 
Fransen ( 139 ) in 1937 reported the results of various observa- 
tions on the overwintered larvae in Holland in the spring of 1937. 
t the end of &pril he carried out experiments on active larvae with 
several poison dusts, mainly derris and pyrethrum, using a special 
dusting box. Dusts of derris and Lonchocarpus containing 0.5, 0.75, 
and 1 percent of rotenone proved inadequate* Fransen ( 14.0 ) later 
described a series of field tests in which rows of infested oaks were 
power-dusted with insecticides at an approximate rate of 4-5 pounds 
per acre on the- 7th or 10th of May. The treatments were largely 
ineffective, as all the trees were heavily infested on May 26 but, so 
far as could be ascertained, they contradicted the laboratory tests, 
as derris dust (0.75 percent rotenone) appeared to have been more ef. - 
fective than pyrethrum containing 0.45, 0.15, or 0.3 percent of pyre- 
thrins, which seemed to be ef'ectiv in that order. 
During 1937 in the Netherlands derris dust containing from 0.5 
to 0.75 percent of rot none was usee successfully for the control of 
this species. — Koloniaal Instituut of Amsterdam ( 241 ) in 1938. 
Spoon et al. ( 386 ) of the Koloniaal Instituut of Amsterdam in 
1937 compared the relative insecticidal value of dusts made from 
derris and cube. Eight set^ of powders were prepared, each set con- 
sisting of one powder prepared with -'erris, the other with Lonchocarpus . 
both powders co taining equally hi-rh amounts of rotenone and ether 
extract. These powders were mixed with diatomaceous earth in order to 
obtain dusts with definite amounts of rotenone (0.5, 0.75, and 1.0 
percent), according to the sensitivity of the various insects. The 
dusts containing 0.7 r percent of rotenone were tested on caterpillars 
of this species. The results are based on the observation of 120 
specimens at least. In 7 of the 8 sets t ; Ffect of derris was 
Stronger than that of Lonrhocar;.us . The' effect of derris ^ust on 
caterpillars of this species is about one and one-tnlf times os stron.- 
as that of Lonchocarpus dust. 
. product containing 12 percent of powdered Lonchocarpus nicou 
root (6 percent rotenone) and 88 ' bed " chrys - 
orrhea " on plum trees, as reported by Ctablias t :mu.nts Rot nia in a 
letter to R. C. Roark in 1938. 
This species was used by Spoon and Van der Laan ( 3Z C ) in 193 r as 
a test insect in correl^tin- - I content of dtr^is with 11 
insecticidal value, (See also unrh r " al-ico .s tria (I,), p. 43 ). 
