FUMIGATING WITH TOBACCO, 89 
are freely used in all the houses. The quantity must 
also be varied. in accordance with the plants growing in 
the house. Some plants are much more easily injured 
by the smoke than others, and the amount used must 
be insufficient to hurt the most tender plants. Less _ in- 
jury is apt to result if the houses and plants are dry; wet 
foliage is quite easily scorched by the smoke. Our method 
of starting a ‘“‘smudge”’ is to place a single sheet of 
newspaper, previously lighted, in the bottom of the burner, 
and upon this the stems are immediately placed. If prop- 
erly dampened, they will take fire readily and smoulder 
without blazing. 
The frequency with which a house should be smoked 
cannot be definitely stated. Some conservatories will re- 
quire the operation scarely more than two or three times 
during the winter, while others may need that many treat- 
ments each week. In the latter case, it is well to have 
the smudges upon consecutive days, as in this manner 
insects receive a second treatment before they have re-_ 
covered from the first. The evening is perhaps the best 
time for fumigating, as most of the disagreeable odor is 
thus escaped. But it may be advisable, in badly infested 
houses, to follow the evening treatment by another the 
next morning. In such cases, care should be exercised 
that the houses do not become overheated by the morn- 
ing sun. 
Tobacco smoke may be used successfully in the de- 
struction of the various aphides which are found upon 
greenhouse plants, and of a small white fly, a species of 
aleyrodes. Other insects cannot be practically treated by 
its use. 
The rose-leaf extract of tobacco we find to be one of 
the best of all insecticides for glass houses. It is a 
liquid, which we reduce one-half with water, then drop 
a large piece of hot iron into it. The fumes are fatal 
to aphis, but have proved to be harmless to plants 
with us. 
