-6- 
Estigmene acrea (Drury), the salt-marsh caterpillar 
If this insect becomes numerous in Arizona before fruit harvest, 
derris is recommended.— Tfehrle (668 ) • 
Bombycidae 
Bombyx mori (L«), the silkworm 
Chemical proof was obtained that dinitro-o-cresol, nicotine, 
rotenone, arsenic trioxide, potassium arsenate, and arsenic pent- 
oxide pass unchanged through the cuticula from the dorsum of the silk- 
worm. Stain reactions demonstrated the presence of permeable areas 
in the cuticula, including that of a living silkworm. ' They occurred 
chiefly in the membranes of the pores of the setae but were also dis- 
tributed over the whole skin« It is highly probable that permeability 
is a purely mechanical process.— Bredenkamp (86) • 
In the laboratory pulverized seeds of Millettia pachycarpa were 
fed to silkworms. It was estimated that the seeds were about one-ninth 
as toxic as rotenone, and about three times as toxic as lead arsenate.— 
Chiu and coworkers (114 ) • 
Insects have been subjected to rotenone toxicity determinations 
more extensively than any other group of animals. The fourth-instar 
silkworm larva appears to be the most susceptible animal tested, as 
far as oral toxicity of rotenone is concerned. The median lethal dose 
is 0.003 mg. per gram. The silkworm appears to be nearly 20 times as 
susceptible as the guinea pig, the mammal most easily affected by rote- 
none. There is no evidence of any definite correlation between the 
position of an animal in classification and its susceptibility to rote- 
none. The comparative toxicities by oral administration appear to be 
similar for derris and cube samples •--Cutkomp (132). 
Seeds of the yam bean, Pachyrhizus erosus Urban, [contains 0.1 
percent of rotenone and 25 percent of fatty oil] used as a dust killed 
100 percent of silkworms, and various extracts of this dust killed 100 
percent or slightly less. An alcoholic extract of the roots of Millettia 
paohyoarpa killed only 32 percent, the stems used as a dust killed 48 
percent, while the seeds used as a dust killed 100 percent. An alco- 
holic extract of cube (4 percent of rotenone) killed only 56 percent 
of the silkworms tested, — Hansberry and Lee (258 ) ; Lee and Hansberry 
(360) . 
The 4, 6-dinitro-o-alkyl phenols and cycloalkyl phenols were nore 
toxio to silkworms than acid lead arsenate, but less toxic than rote- 
none.— Kagy (333). 
