- 72 - 
.Sro^-m (59) in IQ36 rofermd to th-^ use of dcrrl? dust (O. 6 percrnt 
rotenono contf''nt) for the control of Mex:' can bean "be'-^tlvs \rhen;:V--r these 
insects "become troulDlesomo. Trcm 25 to 3^ ;ooundp p^r acre a.rpli^d cncr- 
or twice is usually sufficient. 
Fenton (l27) i-i 193^ ref^Tr'^d to the recomni''^;ndntions cf Ra'ainfjcn of 
Alabama (S_) and Thorras of Texas (367) co^'cerning derris duf;ts and sprpys for 
the control of the Mexican TDca.n Dretle. 
Howard (l90) in 19;^6 reported t^sts made at Colunbu?^ Ohio^i:? 1^35 
vith insecticides against the Mexican "be^'n beetle, Satipfactory control 
wss obtained v^ith svispensionn of derris-root powd-r ai.d cube-root povder i : 
v/at^r at dilutions of 0.01, 0,015, 0.02, and 0,25 p-^rcent of rooenone, 
Fairly satisfactory repult? viere obtained with derris spra:'s containing 
= 005 percent of rotenone, 'X'he incorporation of various vretting agents, 
spreaders, and stickers did not i.Tipro^^e the efficiency of these spray sus- 
pensions. In general, cube "cro^'ed to be ap"nroxi.'^ately ecual in cffecti'''e- 
nes= to derris when te^-ted at the sa.ni'^ dilution of rotonon-'^. Derris- and 
cube-dust mixtures containing OJ'J-, 0«5, ''^-^- 0.75 percent of rotenone with var- 
ious diluents J '•1.1 gave satisfactory control. As a. result of special t'^sts 
of "arious dilu"-nts, it was concluded that it was not important to obtain 
an." particular diluent for use with derris or cube dust, provided such dil- 
uent is nonalVraline in character. The r<^sults indicated that t^.lc-flotation 
ffulfur (50^50), v;hert flour, ground [pyrethrum] marc, talc, b'^-ntonite^ and 
finely ground dusting sulfur, in the ord'^-r named, with th-^: last two aLriost 
eoual in effectiveness, were as good as^ or flight] y supf^rior to, an" of the 
diluents tested. In gf-n"ral, derris dustr apperred to oe slightly superior 
to cub3 dusts in fffcctiveness. 
In a limited number of experim nit s the grcind root of devil' s-shoe- 
strings(Tephrosia vi-Vginiana L,) at a dilation of OfOl p'rcent of rotenone 
gave approxl'iateiy eoual rr suits to those obtained with derris-root ':^owder 
sprays containing the sanie proportion cf rotenone. Drvii ! g_ohoestring'^- 
root dust mixtures containing_ 0. 39 s,nd O-'-l- norcent of rotfnone^ respectively, 
gave satisfactory control and were approximately equal to derris-dust fixture? 
of the same rotenone content. 
Howard (l^Ji) ^^ 193^ reported some rather interesting r'^sults from a 
c.ooperati-'e experiment with other field laboratoiies of the BuTcvau to detf^r- 
rn'n.-' th(^ la.sting effects of derris on bean foliage. Bean plantings i-zoro 
made at the following locations throughout the United State's: F-^w Haven, 
Conn., ITorfolk, Va. , Colu/.ibur-, , 0hi6, Bfton Rouge, La., Madison, Wis., Man- 
ha,ttan, Kans . , Grand Junction, Colo,, Twin Fallc, Idaho, Ventura, C^^lif .. _, 
Cor'/allis, Greg, ^ Puyallup, Wash., and P;\.^onix, Ariz. These plantings vrere 
treated with a derris spray and samples of leaves were ta.ken at given inter- 
vals a,nd sent to Columbus for analysis. In cv^ry case derris was' recovcri^d 
in sufficient q-ua.ntities at the end of 2 wr-k? to be detected by the colcri- 
metric and goldfish methods. At i^dison, G-rand Junction, Twin Falls, Corvallif 
and Columbus derri<-, shovrf^d a slower lop<^. of toxicity than at othf--r la.boratr^ricf 
Light alone did not seem .to account for tV.e decomposition rate, neither did 
high humidity. At Pheonix, where daily temperatures a-"-era.ged ov^r 100'^ F„ , 
derrisi was recovered aft'T 10 days. At A''entura_, where no raiii fel] during 
the test, all the toxicity ha.d disappeared at the end of U wc'ks. During 
this test period Ventura, had 9 foggy Aays, .being the only laboratory where 
fog wa.s r^'ported. 
