220 
TREES AS GOOD CITIZENS 
gouged in the bark of young growth. 
Upon hatching, the young penetrate the 
bark and winter beneath it. In the spring 
they resume feeding on the cambium or 
inner bark. When fully grown, a few 
weeks later, they bore into the wood and 
into the pith, and tunnel a gallery in the 
latter soft material. The presence and 
activity of the borer are shown by dead 
or dying limbs, swellings and dead patches 
of bark, often cracked, on limbs or trunk, 
fading foliage and the oozing of sap and 
“sawdust” from points of attack. The 
half-inch white grub will usually be found 
in the burrow when an injured twig is split 
open. 
arsenate in July, has been found effectual, 
as has also the painting of trees with kero¬ 
sene emulsion in April. 
Cottonwood Borer 
Habits This borer does much dam- 
and age, causing death or so weak- 
Damage. ening a tree as to cause it to be 
broken off by the wind. The 
grub is long and cylindrical, yellow col¬ 
ored, and is hatched from eggs laid in 
July and August, in small punctures in 
the bark, at or below the ground level. 
The young borers mine under the bark 
and deep into the wood, throwing out 
shredded sawdust. The mines thus made 
at the base of the tree are responsible for 
the weakness that makes the tree fall 
before heavy winds. Sickly tops, and 
collections of the shredded borings on the 
ground, are the indications of the borer’s 
work. The borer continues his tunneling 
for two years. 
Remedies. Destruction by digging 
out the young borer is the 
most successful remedy; or carbon disul- 
phid, injected into the hole which shows 
fresh sap and borings, will prove effectual 
if the hole is promptly plugged and sealed 
with grafting wax, putty, soap or clay. 
Spraying the trunk with poisoned kero¬ 
sene emulsion, or miscible-oil, is advo¬ 
cated by some authorities for killing the 
borers when young. 
Carpenter Worm 
(See description and remedies under Maple) 
Twig Girdler 
Oyster-shell Scale 
(See descriptions and remedies under Elm) 
SAP-SUCKING GALL INSECTS 
Poplar Leaf-stem Gall-aphis 
Habits The gall formed by this 
and insect takes the form of a 
Damage, swelling of the stem, in which 
a large brood of living lice is 
born in midsummer. The aphids feed on 
Remedies. Unless the attack is 
exceedingly severe, no treat¬ 
ment is necessary. In extreme cases the 
destruction of the insects may be accom¬ 
plished by gathering the infested leaves 
