FUMIGATION AGAINST GRAIN WEEVILS 15 
Titschack (25) showed that ethyl alcohol was ineffective against 
the eggs and larve of clothes moths. 
MeClintuek Hamilton, and Lowe (/3) found the effectiveness of 
methyl and ethyl alcohols to be low against bedbugs, cockroaches, 
house flies, clothes moths, and mosquitoes. Menthol was about half 
as toxic to bedbugs as carbon disulphide. 
Holt (9) found methyl] alcohol tg be more toxic to cockroaches than 
ethyl or amyl alcohol. All required at least 45 minutes to produce 
death, however. 
Lefroy (11) reported that 70 per cent ethyl alcohol failed to kill 
-any mealworms dipped in it. 
Burmeister in 1836 (3, p. 39) recorded instances of beetles which 
after being immersed in spirits of wine for 12 hours recovered all their 
functions when removed from it. 
Apparently alcohols of the fatty acid series have low toxicity to 
insects and are not suited for fumigants. 
ALDEHYDES 
Crotonaldehyde was much more toxic than n-butyraldehyde. 
Furfural and benzaldehyde showed marked toxicities at concentra- 
tions of less than 1 per cent. The chlorine-substituted aldehyde, 
chloral hydrate, had low toxicity. 
Richardson and Smith (21) tested paraldehyde, aldehyde ammonia, 
chloral hydrate, furfural, and benzaldehyde against aphids. Even 
benzaldehyde, the most effective, was not a practical apiieidee as a5 
per cent solution was required to kill. 
None of the many experimenters with formaldehyde, an effective 
fungicide, has discovered any practical value for it as a fumigant 
against insects. Phelps and Stevenson (20) found a 0.5 per cent solu- 
tion to be effective as a stomach poison to flies, possessing a co- 
efficient of 2.32 as compared with a coefficient of 1 for 0.001 normal 
arsenite solution. Four and 8 per cent formaldehyde solutions were 
less effective than the 0.5 per cent solution; a 1 per cent solution 
had a coefficient of 2.36. ‘The addition of molasses and brown sugar 
diminished the effectiveness of the formaldehyde solutions. Dry 
powdered paraformaldehyde showed a coefficient of only 0.14, 
while a saturated solution had a coefficient of 1.90. 
Moore (15) found that the toxicity of acetaldehyde, chloral hydrate, 
and furfural to house flies in general increased as their volatilities 
decreased. 
According to Davis (5), acetaldehyde is ineffective against white 
sees in soil. Trillat and Legendre (26) report that it has only a 
eeble toxicity for mosquitoes. 
Lefroy (11) found a solution of chloral hydrate in water to have no 
effect on mealworms. Holt (9) reports that roaches dusted with 
powdered chloral hydrate survived for 4 hours. 
McClintock, Hamilton, and Lowe (1/3) found benzaldehyde to be 
more effective than carbon disulphide against bedbugs, cockroaches, ~ 
and house flies, equally effective against clothes moths, and less than 
half as toxic to mosquitoes. 
KETONES 
Ethyl methyl ketone was more effective than acetone (dimethy! 
ketone). The introduction of chlorine into a ketone, as in chloro- 
acetone, enormously increased its toxicity. 
