APHIS. 
179 
wet is not so hurtful to them as is geilerally ima- 
gined.” ^ 
“ Though no mode of destroying Aphides will 
perhaps ever be devised on a large scale in the 
open air by artificial means, we can accomplish it 
most effectually when they infest plants in green- 
houses and frames, or in any situation in which 
we can envelop them for a certain time in clouds 
of smoke. Powders or liquids, however fatal to 
Aphides, must ever be ineffectual, from the trouble 
and difficulty of applying them so that they shall 
come in contact with those insects, situated as 
they usually are; but in this respect smoke has 
every advantage; it penetrates and pervades their 
inmost recesses. The smoke of common veget- 
ables, however powerful, is found to be inadequate 
to their destruction, and hitherto no other than 
that of Tobacco is found to be effectual. That, 
judiciously applied, completely answers the pur- 
pose, without injuring the plant. It mostly hap- 
pens, in well managed houses, that a few plants 
only are infested with Aphides; in such a case 
the smoking of the whole house is a business of 
unnecessary expence and trouble; and we would 
recommend it to persons who have large collec- 
tions to make use of a box of a commodious form 
that shall hold about a dozen plants of various 
sizes, to be used as a sort of hospital, in which the 
infested plants may be smoaked separately, and 
the insects more effectually destroyed, beeause it 
may be rendered more perfectly smoke-tight.” 
‘‘ To prevent the calamities which would in- 
fallibly result from the accumulated multiplication 
