Borers and Bark-beetles 147 
run into the hole, or the worm may be cut out and the scar 
treated like any other wound. 
In any case, tedious individual treatment is necessary, 
there being no wholesale method. Hence, where borers 
are to be feared, preventing their entrance by protective 
covers is the preferable method. Against the larger borers 
a wire mosquito netting, placed around the trunk loosely, 
so as not to touch the bark, set into the ground at the base 
and tied at the top, prevents the beetles from laying their 
eggs either under the bark scales or in a gnawed hole. This 
device also prevents beetles in the trunk from emerging, 
leaving them to die without chance of reproduction. On 
branches, tarred paper or even newspaper will answer the 
same purpose, or else whitewash, to which Paris Green has 
been added, can be thoroughly applied with a knapsack 
pump through a Vermorel nozzle. But this must be renewed 
every week or two until the middle of July, when the danger 
from flat-headed borers is past. Still better is an applica- 
tion of dendrolene or “insect lime’’, which keeps effective 
for the season if applied properly at the right time. But 
all these measures are practically undesirable, and even- 
tually removal of the infected tree is the only resort. 
The most insidious and least amenable to remedies are 
the bark-beetles, the larve of which, minute white grubs, 
burrow in the soft wood and cambium layer under the bark, 
destroying the cambium; and since several broods are made 
during the same season, their numerous galleries eventually 
girdle and kill the trees. Little round shot-holes show the 
inlet and outlet of the small black or brown beetle, but 
when the broods of larvee have been at work for some time, 
the bark is loosened and can be peeled off without resistance. 
Since these beetles hardly ever attack healthy trees, pre- 
ferring those which have been otherwise weakened or under- 
