12 THE COLORADO EXPERIMENT STATION 
If this louse is very abundant, either upon roots or limits, 
the result is an unthrifty tree, bearing small and poorly colored 
fruit. Even if the fruit is worth picking it will be more or less 
smeared with the excretions of the lice, and the pickers may have 
their clothing almost completely colored with the red juices of the 
crushed lice. 
Probably the injuries to the tree are greatest from the root 
attack, but the direct losses to the orchardist are doubtless greatest 
from the injuries to branches and fruit. 
PREVENTION. 
Prevention is usually much better than any remedy, but we 
are seldom aroused into action until we are hurt, and money spent 
on preventive measures is likely to be considered money thrown 
away. The greatest care should be exercised to avoid setting young 
trees with woolly aphis already upon them. Such trees have a se¬ 
vere handicap from the first. To avoid this handicap ])urchase 
trees, so far as possible, from nurseries that send out clean stock 
and then insist on your nursery stock being thoroughly inspected 
by a competent person and, if infected, either reject it or insist upon 
thorough disinfection. 
One way to prevent the root injuries of this louse is to plant 
only such apple trees as are grown upon Northern Spy roots. 
If nursery stock is received with the roots “puddled,” cov¬ 
ered with mud, insist upon the mud being thorouglily washed off 
so as to expose the roots for inspection. This is one way nursery¬ 
men have of covering up the woolly aphis on the roots. 
As we find that the lice seldom are found upon roots more 
than ten inches from the surface of the ground, this is a strong 
hint that the soil for a successful ap])le orchard should be deep, 
and that planting, cultivation, and irrigation should be so man¬ 
aged as to make the trees deep rooted. Set the trees rather deep, 
irrigate thoroughly but not often, and cultivate deeply, from the 
first, between the rows. 
Finally, during the last half of August, before the winged 
lice appear, thoroughly s])ray for the ])urpose of cleaning up the 
lice upon the tree tops, so that the winged migrating form can 
not spread about to distribute the species to other trees. 
NATURAL ENEMIES. 
Notwithstanding the fact that this louse is heavily covered 
with a protective waxy secretion, it is freely preyed u])on by lady- 
beetles (Coccinellid(ie), Syrphus flies, and Chrysopa larvae, com¬ 
monly called aphis-lions or lace-wing flies. The orchardist will 
often notice that certain limbs or trees that were badly infested 
early in July may be nearly or fjuite freed from the lice by the 
