a 
gence of 171 Nemeritis canescens Grav., on larvae of Ephestia figulil— 
ella Greg. and Plodia interpunctella Hbn. At a nearly constant tem-— 
perature of 835.5° F., the parasites completed development in cellu- 
- loid vials in 22.6 days in Plodia hosts and in 24.2 days in Ephestia 
hosts. At 82.3° F., in Ephestia larvae, the parasites developed in 
25.5 days in glass vials and in 22.7 days in vials of celluloid. With 
rare exceptions Nemeritis canescens does not attack host larvae until 
the latter have entered crevices so constricted that they are unable 
to move or writhe about or until they have enclosed themselves in cocoons. 
Emergence of the adult parasite sometimes occurs from the pupa of the 
host. An average of 31 host larvae were killed by each female parent 
observed. Adult N. canescens emerged from about 48 percent of the host 
larvae killed by the female parents." 
Critical temperature for cigarette beetle.--W. D. Reed, Richmond, 
Va., submits a summary of temperature experiments "in the refrigerator 
in March to determine the resistance of cigarette—beetle larvae to sud— 
den changes in temperature. * * * It can be seen that a temperature 
below 20° F. is very critical to larvae of Lasioderma serricorne Fab. 
The relative humidity in the refrigerator ranged from 48 to 74 percent 
during the exposures." 
TOXICOLOGY AND PHYSIOLOGY OF INSECTS 
Rotenone mixture permanently cripples flies.--F. L. Campbell, Tak- 
oma Park, Md., reports that "preliminary comparisons (by himself and W. N. 
Sullivan) of the effect of the pyrethrins and rotenone in kerosene-—cyclo- 
hexanone (9 to 1) showed that rotenone permanently cripples surviving 
flies, whereas the flies recovering from treatment with the pyrethrins ap-— 
pear to be normal in every respect. Because of uncertainty as to the con- 
centration of the pyrethrins in the solutions that were tested a statement 
on the relative lethal action of the pyrethrins and rotenone cannot be 
made at this time." 
A nicotine compound far more toxic to silkworms than is lead arse- 
nate.—-According to J. W. Bulger, Takoma Park, "Nicotine—bentonite con-— 
taining 5 percent nicotine is about 4 times as toxic to silkworms as is 
lead arsenate, when calculated upon a gram-for-gram basis. If calcula- 
tions were based upon the nicotine content only the difference would be 
about 20 times greater." 
Diphenylene compounds toxic to Southern armyworm.--M. C. Swingle, 
Sanford, Fla., reports that "Ten different concentrations of diphenylene 
sulphide were tested on about 650 larvae of the Southern armyworm (Pro- 
denia eridania Cram.). This substance acts more slowly than lead ar- 
senate but over a period of 3 days the toxicity is not much less. Diph- 
enylene oxide was also tested at 10 different concentrations on 520 
larvae. It-was not so toxic as the sulphide at the lower concentrations 
but was about equally so at high concentrations. Its toxicity seemed 
to be about two-thirds that of lead arsenate." 

