May 17,1924 Hydrocyanic-Acid Gas in Protection of Chicle-Peas 
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the seeds made with the same tedious carefulness revealed no living specimens 
of larvae, pupae, or adults. 
In all five warehouses fumigated there were found slight infestations of 
Sitophilus oryza , Plodia interpunctella, and Sitotroga cerealella . The Plodia in¬ 
festations appeared to be easily killed by the fumigations. Large numbers of 
the Sitophilus and Sitotroga were killed, but so many were not that the fumiga¬ 
tions, from the standpoint of their control, could not be called a success. It 
should be said, in passing, that Sitophilus and Sitotroga infestations are not 
usual in chick-pea stocks, bruchids being the only really serious pest, aside from 
the infrequent and devastating attacks of the Rhizopertha. 
OBSERVATIONS MADE SUBSEQUENT TO FUMIGATION 
Many samples of seeds were taken from all warehouses just previous to fumi¬ 
gation (November 29, 1918). These were examined seven months later (June, 
1919). All contained many living adult and immature bruchids and their 
parasites, except a few of the more heavily infested samples which had become 
too badly damaged to support a bruchid infestation, with the result that the 
infestations had burned themselves out. 
Of the hundreds of fumigated samples held for observation only one developed 
living bruchid material. This one sample showed a few living specimens on 
June 23, 1919. Many of the fumigated samples w~ere held for observation in 
the laboratory but developed no infestations up to 1923, although conditions 
were favorable to bruchid development, as indicated by the growth of bruchid 
cultures in other containers and by the ease with which the fumigated seeds 
became infested in 1923 when adult bruchids were given access to them. 
SUMMARY 
It has been generally conceded that commodities such as wheat, corn, rice, 
animal feeds, flour, etc., stored in bulk in farmers’ bins, grain elevators, or 
stacked closely in sacks in warehouses, are not satisfactorily protected by ordi¬ 
nary fumigation with hydrocyanic-acid gas because this gas lacks sufficient 
power of penetration to reach and. kill insects hidden within the commodity. 
Since such food supplies are subject to severe insect attack in storage, usually in 
congested districts where inflammable and explosive gases can not be used without 
danger, all data bearing upon the penetration of hydrocyanic-acid gas are of value. 
Because food commodities in storage under private ownership are of great value, 
subject to removal on short notice according to trade conditions, and therefore 
not available for prolonged study, opportunities for studies upon the penetration and 
effectiveness of insecticide gases are rare and, when offered, should be improved. 
The data recorded on the penetration and effectiveness of hydrocyanic-acid gas dur¬ 
ing the fumigation of 137,000 sacks of chick-peas ( Cicer arietinum) each weighing 
240 pounds, the lot having a retail value of $5,000,000, are new and valuable. 
No similar large-scale practical work with a warehoused commodity has 
previously been recorded. It was found that infestations by Bruchus quadrima - 
culatus, Rhizopertha dominica, Lasioderma serricorne, and Plodia interpunctella 
could be brought under very satisfactory control by fumigation with hydro- 
cyanic-acid gas, as a result of the thorough penetration of the gas throughout 
the bulk of the 240-pound sacks, no matter whether these were stacked four or 
five deep, as chick-peas are ordinarily warehoused, or in piles, the tiers of which 
were often 18 sacks high. Infestations of Sitophilus oryza and Sitotroga cerealella 
were not satisfactorily controlled by one fumigation, though many were killed. 
Since Bruchus quadrimaculatus is the primary pest of chick-peas, fumigation 
with hydrocyanic-acid gas, when generated by the use of 2J^ pounds of 98 to 99 
per cent pure sodium cyanid per thousand cubic feet of space, was shown to be a 
dependable method of protecting chick-peas in storage. Fumigation with 
hydrocyanic-acid gas has now become the standard control in commercial 
establishments handling this food. 
