218 
JOURNAL OF ECONOMIC ENTOMOLOGY 
[Voi r 
over 95% purity were used as the equivalent of 1 ounce sodium cyanide 1 . 
It is obvious from the above table that the equivalent of % ounce 
sodium cyanide per 1,000 cubic feet of space (or loec of liquid) was 
effective against the following common greenhouse insects, Idiopterus 
sp., Illinoia pelargonit, Myzaphis sp., Macrosiphoniella sauborui, Myzus 
persicae , Trialeurodes vaporariorum, Orthezia insignis , Chrysomphalus 
biformis, Coccus elongains, and Thrips tabaci , killing from 97 to 100 per 
cent of them. This dosage, however, was not effective against the 
immature stages of white fly, Trialeurodes vaporariorum, or the adults 
and eggs of the azalea bark scale, Eriococcus azaleae, and mealybugs, 
Pseudococcus citri, or the eggs of the long soft scale, Coccus elongatus. 
Slight tip burning occurred only on chrysanthemums, rose, and Jeru¬ 
salem cherry. These results also demonstrate that liquid hydrocyanic 
acid is equally as effective as the pot method of generating the gas. 
Upon carrying the experiments to the greenhouse it was necessary to 
determine the distribution of the gas and its effect on the hosts. The 
plants in the experiment were divided into three lots, with one lot at each 
end and one in the middle of the house. One plant of each variety was 
represented in each lot and arranged in the same order so that if burning 
occurred it would be in evidence on the same variety of plants in each 
lot and this would serve as an index of equal distribution of the gas. 
Burning occurred on one variety of jasminum in each lot of plants indi¬ 
cating that comparative equal diffusion had taken place. 
It is evident from the experiments thus far conducted that while this 
1 Woglum, R. S., “Fumigation of Citrus Trees for Control of Insect Pests," Far¬ 
mers’ Bulletin 1321, p. 26, 1923. 
