I8 MISC. PUBLICATION 273, U. S. DEPT. OF AGRICULTURE 
ROOT APHIDS 
Some aphids are root-feeders. One species, Cinara (Lachnus) 
curvipes Patch, was recently found feeding on the roots of small 
white firs in Oregon. The large carpenter ants (Camponotus her- 
culeanus var. modoc Wheeler) were carefully tending them. The 
ants had gnawed the outer bark and cambium of the fir roots, and 
colonies of aphids were feeding on the fresh wounds. They were 
observed working the full length of their beaks into the cambium 
and feeding on the juices. This same aphid has been found working 
on the bark of twigs of balsam firs and Cedrus atlantica. 
INSECTS INJURIOUS TO YOUNG TREES (SAPLINGS 
AND POLES) 
Trees in plantations and forests are subject to attack by a great 
many insect pests while they are growing from saplings to maturity. 
After having been at first beset by the root-feeding insects, they 
are later attacked by another group of injurious insects—those which 
feed on the rapidly growing terminal shoots, laterals, tips, or buds. 
This type of damage seldom results in the death of the young trees, 
but it often seriously deforms or stunts them. As buds and termi- 
nals are killed the tree throws out new buds and shoots, which results 
in much branching. ‘The tree becomes bushy in form, with the main 
trunk crooked and gnarled, and is often permanently ruined for 
commercial use. At this stage of the tree’s life, leaf-eating and 
bark-feeding insects also begin to be of importance. 
The control of insects affecting young trees rarely calls for the 
application of direct control measures. A certain amount of insect 
damage is normal in natural forests and is only a part of the natural 
thinning process. When an epidemic develops as the result of some 
disturbance of the natural balance, as through the creation of an 
abundance of slash, windfall, or fire-injured trees, some direct con- 
trol action may be necessary to protect the younger trees. Usually 
the indicated remedy is avoidance of the conditions that induce epi- 
demics or the prompt disposal of breeding material. In plantations, 
or in the case of trees of special value, some attention to insects may 
frequently be justified. 
The control of terminal-feeding insects presents an extremely diffi- 
cult problem. In general little can be done except through spraying, 
dusting, or hand-picking of damaged shoots and encouraging of 
parasites. The cambium-feeding insects can usually be controlled 
by felling and burning the infested material, and leaf-feeding forms 
can be controlled by spraying or dusting. Special methods adapted to 
the control of each group will be mentioned under later discussions. 
KEY TO DIAGNOSIS OF INSECT INJURY TO YOUNG TREES 
A. Terminal shoots, laterals, or tips deformed or killed. Trees weakened 
or stunted but seldom killed (except a few of the smaller seed- 
lings). 
1. New or old twigs, branches, or succulent shoots killed. Insect 
tunnels or borings found under the bark. 
a. Point of attack showing a small pitch tube with exu- 
dation of fine boring dust. Under the bark or in 
pith are found small egg tunnels of uniform 
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