156 
Psyche 
[June- August 
4. A metal covering over the vines gives much better 
results in the number of insects killed than a canvas covering, 
under identical conditions. This appears to be due principally 
to two factors; (1) A metal covering is more air tight; (2) the 
temperature in a metal covering is higher after a certain exposure 
than it is under a canvas tent under a like exposure. 
5. In the winter dormant condition vines are not injured 
by the use of Cyanogas calcium cyanide. Both young and old 
vines seem to withstand with safety such strong treatments as 
10% volume for 45 minutes. 
