230 SCALE-INSECTS, BARK-LICE, MEALY-BUGS. 
ant the fruit is destroyed. One of the most characteristic points 
in the appearance of the insect upon the fruit is the purple dis- 
coloration around the edge of each scale. So far as we know 
this result is confined to this one scale insect. Upon the leaves 
the insects have a tendency to collect along the midrib on the 
upper side of the leaf, in one or more quite regular rows, and 
also to some extent along the side ribs. The infested leaves turn 
brown, but do not have a tendency to fall as a result of the 
damage.” 
How the insect spreads. This scale insect can be carried 
on fruit sent to the market. Large numbers are thus sent long 
distances, and almost invariably reach their destination in good 
health. But as most of such fruit is eaten in the cities or away 
from orchards, there is not so much danger on that account, and 
only where peelings of fruit are thrown about in a careless and 
filthy manner among growing bushes and trees can the young 
lice find a new home. These young lice are decidedly active for 
a brief time, two or three days at most, and they crawl with con- 
siderable rapidity and great persistence, so that they might pos- 
sibly descend from one tree and crawl for a number of yards 
to another; but the spread in this manner is insignificant. Where 
trees are close together they may pass from the branches of one 
to the branches of another. They rarely crawl long in one 
direction, however, but rather move rapidly around, irregularly 
and at random. Usually they do not go further than is neces- 
sary to find a good place to settle and at once begin to form a 
scale. This very interesting process is shown in Fig. 183. As 
soon as the young louse has inserted its beak into the plant, and 
has begun to feed, a change comes over it, and within a few 
hours it is entirely covered with a fine, white, waxy film. This 
turns to yellow and then to gray or even black, and the creature 
is a fixture, absolutely incapable thereafter of shifting its posi- 
tion under any possible circumstances. Strong winds may carry 
the young bodily from one tree to another, but the principal 
method of spread is by means of other insects which are winged, 
and by birds. The active young lice will soon crawl upon any 
small winged insect, particularly if the latter is of a dark color, 
and they may be carried by. it to a considerable distance. They 
also crawl upon the feet of birds which visit the trees and may 
