THE ASPEN BORER' AND HOW TO CONTROL IT. 
By GrorcE Horer, 
Entomological Ranger, Forest Insect Investigations. 
CONTENTS. 
Page. Page. 
Trees attacked by the aspen borer__ 3 | Associated insects and disease______ 9 
Character and extent of injuries____ 4 | Condition of trees attacked________ 10 
BNET DUO, eens BOL ee 7 | Situation and conditions favorab!e 
Seasonal history and habits________ ii HOWE IN” (=a ee 11 
wescription® . see es pet oe 8_ |). Contrelimeasures=.= == >520 = * 11 
Natural enemiess=22 0 8 
TREES ATTACKED BY THE ASPEN BORER. 
XTENSIVE deadenings in aspen trees, due primarily to the 
work of larve of woodboring beetles, occur throughout the 
Pikes Peak region of Colorado. The most common and widely dis- 
tributed insect causing this injury is the aspen borer;! but at higher 
elevations and attacking only the base of the tree another roundheaded 
borer? plays an important part, causing a large percentage of 
windfalls. 
Aspen shade trees are equally susceptible to injury by .the aspen 
borer and are frequently killed or so riddled that they break off in 
the wind. 
Among the native or introduced species of poplars? growing in 
this region none is immune from the ravages of the borer. A very 
large percentage of the various species of poplar in Colorado 
Springs, Colo., and adjacent city parks, together with those in the 
forests of this region, are affected by this insect. 
The heartwood of trees which are repeatedly attacked becomes 
honeycombed, causing dead limbs and tops which are easily broken 
off by the wind, finally resulting in the death of the trees. 
Aspen and poplars generally are looked upon as short-lived trees. 
This is true in a measure, but on Cheyenne Mountain, in Colorado, at 
an elevation of 9,000 feet, the writer recorded over 75 aspen trees, 
growing in mixture with Douglas fir and Engelmann spruce, that 
had attained a size of from 15 to 23 inches in diameter and from 70 to 
1 Saperda calcarata Say. 
2 Xylotrechus obliteratus Lec. 
3 Populus deltoides (common cottonwood) ; P. angustifolia (narrowleaf cottonwood) ; 
P. acuminata (lanceleaf cottonwood) ; P. fremontii (Fremont cottonwood) ; P. occiden- 
talis (western cottonwood) ; P. nigra var. italica (Lombardy poplar). 
184875°—20 3 
