16 BULLETIN 13138, U. S. DEPARTMENT OF AGRICULTURE . ; 
Richardson and Smith (21) found that even 100 per cent acetone 
and ethyl methyl ketone killed less than 95 per cent of aphids, and 
acetal was effective only in concentrations over 50 per cent. 
Moore (i5) found the toxicity of acetone, bromomethyl phenyl 
ketone, and menthone to house flies to increase with diminishing 
volatility. 
Holt (9) found that it took acetone vapor 32 minutes to kill cock- 
roaches, as against 8 minutes for carbon disulphide. 
Lefroy (11) found that acetone killed no mealworms dipped in it. 
According to McClintock, Hamilton, and Lowe (13), acetone has 
very little effect against bedbugs, cockroaches, house flies, clothes 
moths, and mosquitoes. 
Titschack (25) found acetone less effective than carbon disulphide 
against the eggs and larve of clothes moths. 
Guérin and Lormand (7) found that bromoacetone had no apparent 
effect on plants at a concentration of 1 to 2,000 exposed for an hour. 
Bertrand and Rosenblatt (2) found monochloroacetone to be very 
much more active against the larve of (Bombyx) Malacosoma neustria 
L. than ether, chloroform, carbon tetrachloride, or carbon disulphide, 
but less active than hydrocyanic acid or chloropicrin. 
ESTERS 
The esters showed a higher toxicity to weevils than any other class 
of organic compounds tested. Methyl, ethyl, isopropyl, and methyl 
cyano formates and isoamy] acetate are more toxic, molecule for mole- 
cule, than carbon disulphide. Propyl acetate is less toxic than car- 
bon disulphide; n-butyl acetate, isobutyl acetate, and ethyl-n- 
valerate are so slightly volatile at the temperatures used that they 
do not give 100 per cent mortality in the concentrations obtained. 
Richardson and Smith (2/) tested the action on aphids of amyl 
acetate, methyl salicylate, and benzyl acetate. Benzyl acetate, at a 
concentration of about 1 per cent, was the most effective. 
Moore (15) tried the effect on house flies of methyl salicylate, 
ethyl malonate, ethyl acetoacetate, amyl acetate, amyl valerate, and 
propyl! acetate. 
Lefroy (11) found that amyl acetate killed all mealworms dipped 
in it, while methyl salicylate and ethyl acetate killed some. 
Moore (16) tried the effect of a wide variety of substances on the 
clothes louse. He concluded that liquids less volatile or more volatile 
than creosote are not as successful, and that, while not quite as good, 
crude phenol and methyl salicylate are the best substitutes. 
ETHERS 
s-Dichloromethyl ether had an efficiency comparable to that of 
carbon disulphide; chloromethyl ether was about half as effective. 
Acetal was effective at a concentration of slightly over 4 per cent. 
Ethyl ether was the most volatile and least toxic of all materials 
used by Moore (1/5) against house flies. 
Ethyl ether has been tested by a number of other experimenters, | 
but in all cases it showed only a low toxicity against insects. 
CHLOROHYDRINS 
Epichlorohydrin, the most toxic substance tested in this investiga- 
tion, killed 100 per cent of S. oryza at a concentration of only 0.09 
per cent. Ethylene chlorohydrin at the maximum concentration 
tested, 1.4 per cent, was ineffective. 
