HOW TO COMBAT THE ATTACK OF INJURIOUS FOREST INSECTS. 19 
which are laid out, bast downwards, throughout the young wood, 
at distances of twenty paces or so. Underneath each sheet 
are placed a few young twigs of the Scots pine, which greatly 
assist in attracting the insects, and on the top of all is laid a sod 
or flat stone to keep the bark from drying up too quickly. The 
lures should be renewed and replenished two or three times during 
the season, as the old material is apt to lose its charm. Each 
morning from April till September, these traps are visited either by 
the forester, or, which is cheaper and equally suitable, by a boy 
or woman, and the beetles which are found are removed and 
destroyed. This is the best remedy for pine weevils that has 
ever been discovered, and is employed with conspicuous success 
wherever these creatures abound. 
The pine beetle, and all the other members of the great family 
of the Scolytide, can be best, and indeed only, eradicated through 
providing material on which they may oviposit, and in which 
their young may afterwards be destroyed. The procedure is very 
simple, and the results highly satisfactory. From February till 
September, at intervals of a month, trees, which in the ordinary 
course of things would be removed, are felled and allowed to lie 
for six weeks or so, at the end of which time they are peeled and 
the bark burned. The number of “ catch-trees” which one should 
prepare depends entirely upon the abundance of the insects. If 
it be found that all, or almost all, the available space in the trees 
is occupied by breeding galleries, then it is evident that too few 
trees have been provided. If, on the other hand, the catch-trees 
are not much attacked, then fewer may in future be laid dowu ; but 
on every well-managed estate a considerable number of such lures 
should always be present. One must also arrange the species of 
tree to be used as a lure according to the species of insect one 
wishes to destroy. The majority of the Scolytide infest pines, 
but Bostrichus typographus attacks the spruce almost exclusively, 
Scolytus destructor the elm, Hylesinus fraxini the ash, Scolytus 
Ratzeburgi the birch, etc., so that it may be necessary to prepare 
catch-trees of many species, though in the great majority of cases 
the Scots pine suflices. 
In connection with these lures, the greatest amount of care 
must be bestowed upon the selection of the right time in which 
to peel the bark and destroy the broods. If peeling be done too 
soon, the bark is not occupied by so many insects as it can afford 
space for, and consequently an excessive number of catch-trees 
