FUMIGATION AGAINST GRAIN WEEVILS 15 



Titschack (25) showed that ethyl alcohol was ineffective against 

 the eggs and larvae of clothes moths. 



McClintock, Hamilton, and Lowe (18) 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 to 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 w-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 aphicide, as a 5 

 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 

 grubs in soil. Trillat and Legendre (26) report that it has only a 

 feeble 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 (13) 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 (dimethyl 

 ketone). The introduction of chlorine into a ketone, as in chloro- 

 acetone, enormously increased its toxicity. 



