The Aspen Borer and How to Control It. 11 
SITUATION AND CONDITIONS FAVORABLE FOR 
ATTACK. 
Trees on dry, rocky slopes appear to be more subject to attack than 
those on less exposed situations. Along the low, moist creek beds 
and mountain meadows the attack is not as severe as on drier slopes. 
Infestation is most prevalent between altitudes of 6,500 and 8,000 
feet. It has not been found to occur above 9,000 feet.14 
CONTROL MEASURES. 
Control experiments carried on from 1914 to 1917 in various local- 
ities and upon various clumps of aspen have shown that two methods 
are practicable and that the insect can be controlled if not entirely 
eliminated by either of them. The two methods recommended are 
the cutting of “ brood trees” and the application of creosote or car- 
bolineum. 
“ Brood trees ” are those which are attacked for a number of years 
in succession and contain two or more generations of the aspen 
borer. These so-called “brood trees” can be readily distinguished 
from the healthy trees and those injured by other causes by the de- 
formed main trunks, dead tops, limbs, and the brownish liquid and 
frass exuding from the egg scars during May and June each year, at 
which time the larve are active, extending and enlarging their gal- 
leries. As aspen usually grows in clumps, the main centers of infes- 
tation can be readily located. 
First, locate a clump of aspen and determine the extent of the in- 
festation, then with a sharp ax cut down the “brood trees.” These 
can be laid in compact piles and burned or the main trunks split 
and exposed to the sun, which will dry out the wood enough to kill 
the brood. One man with a sharp ax can cut and treat 50 or more 
of these trees in a working day, as aspen as a rule is of small diameter. 
Where it is essential or desirable to preserve the trees, the paint- 
ing of the egg scars with carbolineum has proved a successful method 
of control, though not as effective or practicable in large and remote 
forested areas. On private lands and city parks, where poplars are 
valued for their shade and ornament, this remedy can be used to ad- 
vantage. 
Creosote should be applied to the egg scars with a 2-inch brush. 
It is important that this work be done thoroughly. October is the 
time to apply the creosote, after the adult beetles have deposited 
their eggs and most of these have hatched into tiny larve or borers. 
144In some sections of the country injury occurs down to sea level.—F. C. C. 
WASHINGTON : GOVERNMENT PRINTING OFFICB : 1929 
