OYSTER-SHELL BARK-L0TJ8E. 4rl 



to a pailful of water. Even of this strenojth 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 Dr. Mygatt's experi- 

 ence (Trans. 111. St. Agrlcult. 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. No 

 such application, at the same time safe and eflfectual, 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 treas, whilst 

 others assert that it does not injure them. Even if the greasing 

 process were unobjectionable, there would still remain the difficulty 

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