THE IMPORTED PINE SAWTLY. 21 
1914; in France, in 1906; in Sweden; in Norway, in 1914, when the 
larvae nearly defoliated 10-year old pines on one plantation; and in 
England, where they are said to injure Scotch fir as well as pine. In 
many of these infestations D. simile doubtless took a prominent part 
and in some instances may have been the chief depredator. 
Should D. simile become permanently established in this country, 
it will be capable of great destruction. At present it is probably 
confined to nurseries and estates, where it is doing sufficient damage 
to attract considerable attention, and nurserymen and gardeners are 
endeavoring to exterminate it. 
CONTROL. 
In the United States the seeming preference of Diprion simile for 
young trees makes this sawfly primarily a nursery pest and a nur- 
sery problem rather than a forest problem. This confinement to 
trees in nurseries and on estates is of considerable advantage in an 
attempt to eradicate or control the species, since in such situations 
the best opportunities for combating it are found. The infestation 
is more easily observed early in its course, and methods of control 
can be employed which, despite their effectiveness, could hardly be 
recommended to check a forest invasion, owing to the inaccessibility 
and vastness of the area. Because infestations of the sawfly are at 
present limited to young trees in nurseries and under similar condi- 
tions, it is doubly important to combat it now, first, to check its rav- 
ages, and, second, in the hope of exterminating it or at least pre- 
venting it from ever becoming established in our forests. 
In the effort to control the species its life-history and seasonal- 
history advantages, already referred to, should be taken into con- 
sideration and strict watch maintained against its appearance or 
reappearance. 
Infested trees should be sprayed with some stomach poison, such as 
a mixture of lead arsenate and water in the proportion of 2 pounds 
of powdered arsenate of lead to 50 gallons of water, or, in smaller 
quantities, 6 teaspoonfuls of the powder to 1 gallon of water. A 
knapsack, barrel, or tank spraying outfit, whichever is available and 
convenient to use, should give good results. 
Hand picking and dropping or shaking the larvae into pails partially 
filled with kerosene, crushing them with the hands protected by 
leather gloves, and knocking or jarring them from the trees and 
treading on them, are all possible methods of control, especially where 
labor can be obtained cheaply. Such methods as these have been 
used successfully in Europe. 
