295 
emulsion was applied presented insects which were not certainly dead, 
but had changed color, assuming a duller tint and losing the normal 
bright, glistening yellow of the healthy individual. The same effect, 
but to a much less degree, was noted in the case of the tree to which 
pure kerosene oil Avas applied. Examined March 20, no certainly dead 
insects were noticeable in the treatment with diluted emulsion, but with 
the pure emulsion all were dead and rapidly drying up and turning 
black. Upon the tree treated with pure kerosene emulsion the scales 
were nearly all in the same condition, perhaps 10 per cent, showing 
evident signs of life. Examined April 2, kerosene emulsion five times 
diluted did not appear to have killed a single insect. Diluted two and 
one half times, 10 per cent, had succumbed ; the rest Avere apparently 
uninjured. The pure emulsion had resulted in the destruction of every 
individual ; they were all dried up, flattened, and of a black color. Pure 
kerosene had resulted in a precisely similar outcome, A certain yel- 
lowing of the inner bark of the trees in the case of the last two appli- 
cations would seem to indicate that some injury was done to the tree, 
although this may have been due to the injury resulting to the tree from 
the unusual abundance of the scale itself. All the trees treated have 
bloomed abundantly, and are now (April 10) coming out in leaf; they 
appear to be nearly as thrifty as untreated trees similarly infested. 
It will be seen from the above that this scale is a most difficult one 
to treat successfully during the dormant winter period; that it with- 
stands with very little injurious effect the treatment with winter washes 
which have been measurably successful against the San Jose Scale in 
California; and that even double strength of the winter resin wash 
fails in practical results, since at least 50 per cent of the scales were 
not injured. A very strong application of kerosene emulsion diluted 
five and two and one-half times, each applied during the growing season, 
would certainly result in the death of the trees and fail also to kill any 
large percentage of the scales. The pure kerosene emulsion, which, on 
account of its thickness, adhered to the bark with considerable persist- 
ence, and the pure oil, were the only applications which were at all sat- 
isfactory, and it yet remains to be developed whether the trees them- 
selves have been injured by these applications. We can therefore have 
very little hope of success from winter treatment unless in the way of 
pure kerosene oil or pure kerosene emulsion, if it should prove that 
these are not seriously injurious to the trees; and it will undoubtedly 
be necessary to treat the scale either by a system of extermination, 
uprooting and burning the trees, or by treatment with summer washes 
at the time the young hatch and begin crawling about in an unprotected 
state over the trees. At this period the ordinary ten-times-diluted kero- 
sene emulsion or any of the standard caustic insecticides, summer resin 
wash, etc., would undoubtedly result in the destruction of the insect. 
20393— No. 4 2 
