208 DISEASES AND INSECT ENEMIES. 



for by doing- so death would unques- 

 tionably result in a few seconds. Pre- 

 vious to setting off the gas all the ventilators must 

 be put down, and if the house is loose it is well to 

 sprinkle the roof with water. Arrangements 

 must be made, however, for opening some of the 

 ventilators from the outside. From the 

 time the gas begins to generate it should be 

 allowed to remain twenty minutes in the house 

 and then the doors and ventilators should be 

 opened from the outside and air freely ad- 

 mitted. When opening the ventilators from the 

 outside take care not to breathe the gas. The 

 house should not be entered under any circum- 

 stances for half an hour, for it will take at least 

 that time for the fumes to be driven out. 



Unless the aphides are very abundant it will not 

 be necessary to use the gas more than once a month 

 during the growing season. However, the fumi- 

 gation should not be done at regular periods, but 

 should be carried on whenever there is sufficient 

 evidence that aphides are increasing in undesira- 

 ble numbers. This treatment never fails to do 

 the work when proper care is taken, and there is 

 no injury whatever to foliage or flowers. 



Cut Worms. The leaves of violets are some- 

 times attacked and injured by cut worms. This 

 is especially the case in late spring after the new 

 plants have been put out. The cut worms, as a 

 rule, are more troublesome in houses where sash 



