Fr-ytaud and dp L^^rarent ( 132 ) in 1939 do-^criV'-^A eTT^-rinentp 
carried out in Francr- in 1933 to conparo thr- inprcticidal valup of a 
cuop dugt (6 prrcpnt roton^^ne content) used alone or in conbinati^n with 
v^.ri'^us diluent?, oach mixt\arc contnining I5 percent of cutn. Fourth instars 
of thf> potato "bretle worr- ust'd a<5 th'-- test insoct?. Th*^ reaults s'lowod 
that the mixturr-g wer(~ practically as toxic as thp pur?? cu'''^, which causf^d 
fatal paralysi? of the larvae in ler.ft than 2 h^urs, and that calcium carh^n- 
at-, '-•ulfur, kaolin, corbcnat'^d talc, or (cyrB^x'i wer^ •■^refora'bl'^ to fiilic^ , 
"b^^ntonite, or lime. 
To teat their dura-ility , th^ duats wore kept in closed metal I^ot'^? 
for 3 f"-3ad 13 m'-^nthp or exposed in layer's -f 2 to 3 inni, to lij^ht and chan<::eg 
in temperature and hunidity in an insectary for 3, 5, and I5 m-^nths. There 
was no decrease in the toxicity of the dusts keiot in met-ol "boxo's, with the 
exce-otion of the mixtures c^ntaininc-: bi'sntonite and llne^ -f vrhich the toxic 
acti-n -n the larvae was delayed for several h-^ur^. Of the dusts exDosed, In 
the insectary, culDe alone and niixturcp of it with calciu-^ carhonat' , t-^lc, 
sulfur, carhonfted talc, or A:;ypstim retain^^d th"ir full toxicHy ev^n aft-r 
15 'n'-^nths; whereas the y-aralyzinf; effect '^n the larva^- of the dust« c^ntain- 
inrv kaolin and silica was delayed for several hours, and that of the line 
iTiixture for several days. The "bcntonite nixtiire shewed a very retf'rded 
action after exijosurc-s of 3 ^nd 5 'i^nths, and aft' r 15 months it turned into 
a solid mass and vrhen oroken uj did not affect the larvae placed on it. 
In experiments in May 1939 a potato plant protect'^d from r»in "but 
not from air, " i^rht or hu'nidity wap d-usted with a nixtur^^ of derris and 
talc containing 0,25 p^rcont of rotenone and larvae of Leptinotorsa decen- 
lineata were placed on it the s^-ne daj' or at vari'^us intervals. All those 
placed on it 27 days later, the longest interval tested, died within 2U 
hours. In further tests in Jun--^ 193*^ a coi^nnorcially prepared dust contain- 
ing 0.65 percent of rotenone and. stated to he flta>:ilized a^ain^t the off'~cts 
of air and "bright light was found to "be considerably slower in its flcti-.n 
t^an a nonota'rilized du^t containin.c^ only 0,3 percent of roten^^ne, whether 
used after havin,^ been kept in an air-tight box or after 9 days' exposure 
to bright sunlij-'-t. The addition of a color in^:; a<^ent to the second dust 
did. not increase its toxicity. 
The Internati-n?l Institute of A riculture (22l) in 1^39 stat'^d that 
rotenone -nreioarationa are remarkably effective avainst Colorado potato beetlea 
in the errly star-'es, 
Nelson and Howard (293) i^ l'^3'^ re-sorted that cxn -ri-ients in 1*^38 in 
6hio showed that standard sT>rpys c^ntainin^: lea-', arsenate at th"^ mte of U 
pounds to 100 (gallons of water wer- far superior to derris arrays cent^^in- 
in.T 0,015 percent of rotenone, phenothiazine, ^r sxilfur nitride (22,9 loer- 
cent pure), each at the rate of U pound.s to 100 i'ollons of v/ater, for the 
control of the Colorado potato beetle, Tv;o or'-*^liceti'^ns of ench '^f the-^o 
sTorays wi--re made, Althrufh slower in actinn, sulfur nitride conr.ared favor- 
ably with phenothipzine and with derris at the exoirati'-n of 3 wp^-ks after 
the second ar^plic^ticn; however, only lead arsenate gave satisf'^ctor." control 
at the expiration of the 3-week p-ri^d. The nddit-'on-^f a varnish sticker 
to the derris spray did not i-prov^ t)-.-- prr-entn .0 ^f cntr'^^l. 
