41 
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to a pailful of water. Even of this strength it discolors the 
foliage, but does not kill it. The one great difficulty in the way 
of exterminating the bark-lice, is their habit of spreading on to 
the terminal twigs. Here they do most of their mischief, and 
here it is most difficult to reach them, and we are debarred from 
using very efficient washes on account of the tenderness of the 
foliage. The practical rule is this : with a whitewash brush wash 
over the trunks and branches of the trees as far as you can reach, 
with the strong solution, one part soap to four of water; then 
syringe the remainder with the weak solution, two or three cups 
of soap to a pailful of water. The strong solution will kill every 
louse it touches, and the latter, according to Hr. Mygatt’s experi¬ 
ence (Trans. Ill. St. Agricult. Soc., I, p. 516), will kill about half 
of them. But this is the best we can do, unless we take a dull 
knife and scrape every twig, which might be done on one or two 
very small trees, but would of course be utterly impracticable in 
an orchard. The above course, to be successful, must be put in 
practice when the young lice have just hatched, or within a few 
days thereafter. This time varies two or three weeks, according 
!to the character of the season. The usual time is the last week of 
May or the first week of June. But this year they began to hatch, 
in the latitude of Chicago, on the 15th of May, the season being 
unusually hot and dry. The only way to be sure is to watch, and 
examine the trees at this time of the year with a pocket lens, each 
one for himself. 
But the great desideratum is something that will kill the eggs 
through the scale, without injuring the tree, and which can there¬ 
fore be applied in the winter or early spring, when farmers are 
most at leisure, and when there is no foliage to be damaged. Ho 
such application, at the same time safe and effectual, has been dis¬ 
covered. The scales are sufficiently thick and impervious to pro¬ 
tect the eggs beneath from any of the ordinary applications. Even 
undiluted soft-soap does not affect them. Greasing over the in¬ 
fested branches with any kind of oily substance, is sure death to 
them, but it is questionable whether it does not also injure the 
tree. Mr. Walsh collected much testimony upon the subject, but 
it is very conflicting. Some say that it killed their trees, whilst 
others assert that it does not injure them. Even if the greasing 
process were unobjectionable, there would still remain the difficulty 
Yol. II—38 
