FUMIGATION AGAINST GRAIN WEEVILS 17 
Apparently chlorohydrins have not been tested by other experi- 
menters with insecticides. 
SULPHUR COMPOUNDS 
Methyl and ethyl thiocyanates and allyl isothiocyanate were more 
effective than carbon disulphide; methyl and ethyl sulphides and 
ethyl mercaptan were less effective than carbon disulphide. Butyl 
mercaptan was as effective as carbon disulphide against S. oryza, but 
only half as effective against the other species of weevils. 
Mercaptol is so slightly volatile as to be ineffective. Cyanogen 
sulphide killed no weevils at a concentration of 0.1 per cent; per- 
chloromethyl mercaptoland p-toluenesulphochloridegave variable kills. 
Richardson and Smith (2/) found that a concentration exceeding 
5 per cent of carbon disulphide was necessary to kill aphids, whereas a 
solution containing less than 2 per cent injured the nasturtium plant. 
According to Moore (15), molecule for molecule, allyl isothiocyanate 
is more toxic against house flies than chloropicrin, and carbon disul- 
phide and ethyl mercaptan are more toxic than their relative vola- 
tilities would indicate. : 
Tattersfield and Roberts (24) found allyl isothiocyanate to be the 
most toxic to wireworms of all compounds tested by them. ‘The 
toxicity of carbon disulphide was equal to that of benzene. 
Speyer (23) found ethyl mercaptan to have no effect on red spiders. 
It A failed to kill adult white files. 
NITRILES AND ISONITRILES 
n-Valeronitrile had a toxicity as great as that of carbon disulphide; 
acetonitrile was about one-fifth as toxic as carbon disulphide. Pro- 
pionitrile and phenylisonitrile were ineffective. Phenylacetonitrile 
was the most toxic of this class of compounds, killing all S. oryza at a 
concentration of 0.10 per cent. 
Moore (14) found that the toxicity of benzonitrile to house flies com- 
pared with that of iodobenzene and xylene. 
NITRITES 
n-Butyl nitrite and isoamyl nitrite were about equally toxic. 
Moore (15) found that amyl nitrite had about the same toxicity to 
flies as gasoline. 
Tattersfield and Roberts (24) found that the toxicity of amyl 
nitrate to wireworms was low and tkat the toxicity of amyl nitrite 
was moderate. 
Speyer (23) found that the grubs of a chironomid fly (Orthocladius) 
came to the surface of the soil of cucumber pot plants and were killed 
in a short time when amy! nitrite and amyl nitrate were used. He 
also found that methyl nitrite had a more permanent effect on red 
spiders than amyl nitrate and tetrachlorethane, but that it was 
necessary to use concentrations which hurt the plants. The adults 
of the white fly were killed by all these vapors. 
NITRO COMPOUNDS 
Nitromethane was the only nitro compound which killed all of the 
insects; a concentration of 3.6 per cent was necessary. Nitrobenzene, 
p-chloronitrobenzene, m-dinitrobenzene, and a-nitronaphthalene at 
Saturation concentrations killed none of the weevils. 
Moore (1/5) found nitrobenzene even more toxic than nicotine to 
house flies. 
15685°—25}——3 
