146 Control of Parasites 
out borers, to prevent egg masses from hatching, and to 
kill scale insects. 
The insects which can be controlled by such bands are 
all those whose caterpillars are hatched out below the region 
of the band, but it is also useful with those which wander, 
seeking for new supplies after having defoliated one tree. 
It is, of course, necessary to apply the band in season, 
before the caterpillars begin to wander. 
The application of a lime wash (whitewash) to the trunks, 
has been very frequently practised, and it is without ques- 
tion a good protection against several insect pests, especially 
scales. It acts merely as a repellant, not as an insecticide. 
But the unsightliness should rule this remedy out for orna- 
mental trees, wherever other methods are available. If 
used at all, the addition of flowers of sulphur' (making 
bisulphide of lime), or else the addition of crude carbolic 
acid (one pint to a hundred pounds of lime) will increase its 
efficiency. 
Like all such coatings, the lime wash must be renewed 
to remain effective, since it is washed away by rains. 
Borers and Bark-beetles. While there are many ways of 
combating the insects which attack the leaves and which 
live within reach, the various borers and bark-beetles are 
much more difficult to deal with since they are hidden from 
direct access during much of their life and especially during 
their dangerous stage. If their holes can be found, which 
is not always easy, the injection of carbon bisulphide into 
the tunnel and plugging the outlet tight with putty or hard 
soap will kill them, the bisulphide developing a gas injurious 
to the boring larva. Or else, they may be reached by a wire 
1 Five pounds of sulphur and five pounds of lime boiled together in a 
small quantity of water until dissolved, making a brownish liquid, to be 
diluted in a hundred gallons of water. 
