HOW TO COMBAT THE ATTACK OF INJURIOUS FOREST INSECTS. 15 
are unhealthy, or which have been damaged by wind or snow, 
must be removed, and a watchful eye should constantly be kept 
on the woods, so that trees which appear likely to die are at once 
removed, as it is in such trees, or in trees which have just died, 
that destructive insects find their most congenial breeding-places. 
The practice of only removing trees from the wood some months 
after they have died does nothing to keep insects in check, for 
it is not dry and withered trees, but such as are still supplied 
with sap, that forest insects make use of for breeding purposes. 
3. Harvesting the Timber.—Nothing conduces so much to the 
increase of many destructive insects as bad management in con- 
nection with felling and utilising forest produce ; and, conversely, 
woods which are well managed in this respect are preserved from 
the attack of many insects. The chief point to be observed is to 
get the felled timber removed from the wood, and marketed or 
converted as quickly as possible. Where any difficulty is expe- 
rienced in this respect, it should at least be peeled, and, if possible, 
peeled at a time when the bark is full of larve, for, by so doing, 
large numbers of destructive insects are got rid of, and the prac- 
tice, from being merely preventive, becomes remedial. These 
precautions are most necessary in the case of conifers, for it is in 
them that forest insects breed most abundantly. Where the 
ground is suitable the trees should be cut close to the ground, but 
where, as on steep declivities, this cannot be accomplished, the 
stools ought to be stripped of their bark. It is sometimes possible 
to get the bark removed without incurring any expense by allow- 
ing cottagersito strip it off for firing purposes, and the same holds 
true with regard to branches and the general refuse left after trees 
are felled. Not only do stools and branches supply breeding- 
places for Scolytidew, but also for weevils, hence the reason why 
Hylobius abietis is so destructive to young trees planted on land 
previously occupied by conifers. 
The preventive measures which have been noted do not by any 
means exhaust the list, though they are certainly the most 
important. Let me now say a few words with regard to measures 
for the general eradication of insects. 
Theoretically, insects may be destroyed during any or all of the 
four stages of their existence, that is to say, as eggs, larvee, pupe, 
or imagines, and also during any season of the year; but in 
practice the best stage or season to select depends upon the life- 
history of the insect to be destroyed. It is comparatively seldom 
