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seriously in limited localities. Green-house and other in-door plants, 
if not carefully watched, are likely to be seriously injured by them, 
but a little precaution with a knowledge of the proper remedies and 
preventive measures, such as those recommended, will generally suffice 
to eradicate them. * 
If the latter part of the winter is open, and the spring warm, 
bringing them out in advance of their enemies, they are then more 
apt to be abundant and injurious than ordinarily, as they are thus 
enabled to get the start of the latter, and the ascendency thus obtain¬ 
ed, is not easily overcome. 
The true Aphides are generally quite sensible to cold, being large¬ 
ly destroyed by heavy frosts, and severe cold spells; but, as already 
shown there are exceptions to this rule; and it is more than likely, 
that this depends to a great degree upon the effect the cold has upon 
the plants on which they reside. Some, and possibly most, of the 
woolly species appear to be less injured by the cold, than the various 
species of Aphidinm\ but it is quite natural that this should be so as 
the latter reside chiefly on the foliage of plants, while the wooly 
species are found chiefly on the stems, branches, trunks and roots. 
It is supposed by many that the insects of this family are easily 
affected by water, but Cartis states that he “has been surprised to 
see how slightly they are affected by wet,” that “some Aphides at¬ 
tached to a willow twig were immersed in water for sixteen hours 
which did not appear to incommode them in the least, for, on being 
taken out and placed in the sun they increased and multiplied short¬ 
ly afterwards.” Root-lice during winter and the wet weather of 
spring are often subjected for a long time to moisture which does not 
appear to destroy them. Yet other species immersed but for twelve 
hours have been thereby destroyed showing a wide difference in spe¬ 
cies in this respect. The experiments tried in France upon the root 
form of the Grape Phylloxera indicate the inefficiency of this agency 
in destroying this species, as shown by the extract from the report of 
the commission appointed to investigate this species, given above. 
The author quoted above also further remarks that “their capability 
of resisting some gasses or effluvia is very astonishing, for instance, I 
have corked some up in a quill containing a piece of camphor, which 
produced an atmosphere that killed most insects in a hour, but the 
Aphides were walking about unaffected after being confined there for 
twenty-four hours.” The fumes of tobacco and sulphur, are perhaps 
the most potent gasseous agencies in destroying them which are sus¬ 
ceptible of general practical application, and should therefore be re¬ 
sorted to wherever it is practicable to use them. Alkaline substances 
in powder or solution, acrid solutions, kerosene and oils, are generally 
fatal to them where they can be applied directly; but in order to be 
effectual these should be applied with a brush, as if but a few are 
left they soon replenish the colonies. I have noticed that when 
sprinkled with dry dust they cease to multiply and die. The amount 
of moisture which escapes from them while they are actively feeding is 
very large as may be seen by placing a leaf or twig covered with them 
in a bottle; in a short time the sides of the bottle will be covered with 
moisture to such an extent as to run down in drops. Dry dust or powder 
absorbs this moisture, and hardens the outer skin which is fatal to 
their existence. 
