440 
JOURNAL OF ECONOMIC ENTOMOLOGY 
[Vol. 17 
The writer feels that it is fair to assume that infestation coming 
from foreign countries, either on this continent or elsewhere, will be 
prevented through the activities of the Federal Horticultural Board in 
cooperation with state agencies. This being the case, the gipsy moth 
problem then involves either the extermination of all infestations within 
the limits of the United States, or the extermination of part and the 
adequate prevention of the movement of infestation from the balance. 
As matters now stand it looks as if gipsy moth infestations outside of 
New England can and will be exterminated. It also looks as if exter¬ 
mination of Gipsy moth infestations within the New England States can¬ 
not be accomplished in a limited space of time, and that therefore ex- 
terminative work should be pursued in dealing with all infestations out¬ 
side of the New England States and that movement of infested material 
from the New England States into other parts of the United States 
should be so restricted as absolutely to prevent the escape of infestation 
from that area into other parts of this country. 
STATUS OF HYDROCYANIC ACID GAS TREATMENT OF 
NURSERY STOCK 
By John J. Davis, Purdue University, Lafayette, Ind. 
Abstract 
Summarizes complaints from both nurserymen and from orchardmen relative to 
injury to nursery trees when fumigated with hydrocyanic acid gas and the factors 
involved. The need of further experiments with the gas and additional materials and 
probable plans for such investigations are suggested. 
With the early recognition of the San Jose scale as an orchard pest of 
first-rate importance and the recognition of the nursery as the biggest 
factor in its spread to new localities, state laws were enacted in rapid 
succession. The discovery of the value of hydrocyanic acid gas as 
an effective agent against the scale and the comparative ease with 
which it could be used led to the almost universal adoption of this 
method of treating nursery stock. 
We have all heard of occasional complaints from both nurserymen 
and from orchardmen relative to supposed injury to trees by hydrocyanic 
acid gas. Probably none of us, however, have recognized these com¬ 
plaints as general because they were not openly brought to our attention. 
When the matter was first brought to the writer’s attention a year ago 
by Mr. R. A. Simpson, following his presentation of the subject to the 
Illinois Horticultural Society, we immediately made an effort to gather 
