222 JOURNAL OF ECONOMIC ENTOMOLOGY ’ [V61. 17 
humidity conditions for these experiments were as follows: 73° F.. 
and 84%; 72°F., and 75%; and 68 F., and 83%. 
The dust was applied in the units to be fumigated by means of a small 
hand duster to insure equal distribution. Since hydrocyanic-acid gas is 
given off when the particles of calcium cyanide dust are exposed to 
moist air it was assumed that by forcibly blowing the material into a 
greenhouse a nearly complete reaction should take place resulting in a 
maximum liberation of gas. Encouraged by the slight degree of injury 
indicated in Table III, a larger house of approximately 18,000 cubic 
feet of space involving many varieties of bedding and ornamental 
plants was fumigated in the manner just described, and with similar 
results. 
From the evidence of plant tolerance thus far obtained with very 
susceptible plants it seems likely that this material can be adapted for 
greenhouse fumigation purposes. However, considerable investigation 
remains to be done before its status as a greenhouse fumigant can be 
definitely assured. These investigations involve (1) perfecting methods 
of application, (2) determining the rate of evolution of gas under vary¬ 
ing atmospheric conditions, and (3) ascertaining its insecticidal efficiency. 
President A. G. Ruggles: The next paper, will be read by C. C. 
Compton. 
THE USE OF LUBRICATING OIL EMULSION ON GREENHOUSE 
SCALE INSECTS 
By C. C. Compton, Natural History Survey , Urbana, III. 
Abstract 
Lubricating oil emulsion spray at 1% strength has proven very effective in con¬ 
trolling scale insects,Coccidae, under greenhouse conditions. No injury to palms 
has resulted from the spray at this strength with the exception of one case of very 
slight injury when the application was made on a very cloudy day. On bright, 
sunny days a spray at 2% strength has been used without injury but is not recom¬ 
mended. 
There is a distinct demand for an insecticide for use in combating 
scale insects on greenhouse plants. Since scale insects are most trouble¬ 
some on foliage plants, grown largely for the attractiveness of their 
leaves, it is important to have an insecticide that will not injure the 
foliage and yet be effective against the scale. The work with this 
emulsion was carried on by the writer in the Chicago district during 
1922 and 1923. 
