where one ounce to a thousand cnl^ic feet for five hours severely 
injured the cucumbers. Cucumbers are ahvays apt to be injured 
if in fruit at the time. One ounce to a thousand culfic feet has been 
used for tomatoes without injury. One-third of an ounce to a 
thousand cubic feet has proven very beneficial for the Green Fly 
on lettuce, radishes, and similar plants, without injury. Cyanide 
is particularly, beneficial for Green Fly on violets since violets 
cannot be fumig'ated with tobacco. Cyanide will not always kill 
the Red Spider, although probably killing many of the older specf- 
mens, usually leaving the eggs and probably some young which 
will serve to continue the pest. 
A number of factors in the fumigation of g'reenhouses are still 
to be determined and the author would be glad to hear from any 
one who has fumigated greenhouses, giving the effects of the fumi- 
gation and also the conditions under which fumigation was done. 
In closing, considering our present knowledge of green- 
house pests, it would be well to advise the use of not more than 
one ounce of cyanide to each thousand cubic feet for over night 
use, and not more than three ounces per thousand cubic feet for 
fumigation of a half hour. If either of these doses are used and the 
insects are not killed while the plants show no injury, the amount 
of cyanide per thousand cubic feet could be increased but not 
exceeding five or six ounces ])er thousand cubic feet as a maxi- 
mum quantity. 
WILLIAM MOORE, 
Chief of Section of Truck Crop and Greenhouse Insects. 
