FUMIGATION OF ORNAMENTAL GREENHOUSE PLANTS. 11 



commonly recommended for scale insects cost approximately 4 cents 

 per gallon with an average cost of 16 cents per 1,000 cubic feet for 

 each treatment. A 5 per cent homemade kerosene emulsion costs ap- 

 proximately one-half cent more per 1,000 cubic feet than does the 

 gassing method, and gives very indifferent results. 



The foregoing figures do not take into consideration the cost of 

 labor. However, the time required for fumigation will not exceed 

 the time required for the mixing and application of the sprays. 



PRECAUTIONS. 



Do not guess the amount of chemicals to be employed or the cubic 

 contents of the house. 



Do not fumigate plants in a greenhouse in daylight. (For box 

 fumigation in daytime, see page 9.) 



Do not fumigate when the temperature in the house is below 50° 

 or above 70° F. 



Do not leave the chemicals within reach of those unacquainted with 

 their poisonous nature. Always have them properly labeled. 



Do not handle the chemicals any more than is absolutely necessary, 

 and always wash the hands thoroughly after doing so. It is well to 

 have a pair of old gloves for this, and to use them for no other pur- 

 pose. 



Do not allow the acid to splash or drop on the clothing or skin. 



Do not stay in the house any longer than is necessary to place the 

 cyanid in the jars, and never enter a house charged with gas until it 

 has been thoroughly aired. 



Do not fail to post danger signs at all entrances before setting off 

 the charge, and to see that the house is tightly closed. 



Do not attempt to fumigate without adjusting the ventilators so 

 that they may be operated from the outside. 



Do not attempt to fumigate a large house alone. 



Do not fumigate a frame adjoining a dwelling without notifying 

 the occupants before fumigation and allowing them time to leave. 

 Houses contiguous to fumigated frames should be aired thoroughly 

 before the occupants are allowed to reenter. 



Do not pour the water on the acid ; pour the acid on the water. 



Do not become negligent in any of the precautions; to do so may 

 •cause serious results, 



PLANTS AND INSECTS FUMIGATED IN GREENHOUSES. 



Table I is offered as a guide to those desiring to employ hydro- 

 cyanic-acid gas for controlling greenhouse pests. Space will not 

 permit the inclusion of all plants which have been fumigated by the 

 writers, but the table includes many ornamentals and a few tropical 

 and subtropical plants commonly grown in greenhouses. 



