i 111 ii \i 1:1.1-- 1 11; Miii. 
CHAHA< 111: IJ] INJURE \ M> DESTRl't I l\ 1 \ I --. 
The mile-. pass the winter on the trees, under the bud scales, and 
attack ilic leaves as soon a- these begin to «push oul in the Bpring. 
They bore -mall hole-, from the underside t" the interior '»f the leaf, 
where they deposit their eggs, and with their progeny feed upon tin' 
tender cells of tin 1 leaf substance. Their activities within tin- leaf 
tissues very quickly resull in the developmen! of galls or swellii 
These an- at (i 1-- 1 -mall, pimple like eruptions, especially evident on 
the upper surface of young leaves, whitish in color on the apple, 
but usually with a reddish t inge 
on the pear. The spots 
increase in size, the largest be- 
coming a- much as one-eighth of 
an inch in diameter. On pear 
leave- the -pot-, as a rule, be- 
come re.I. often brilliantly col- 
ored a- they grow, whereas on 
apple this reddish coloring i- ab- 
sent or faint. ( )n the underside 
of the leaf the oralis are whitish and blisterlike, not differing much 
from the general color of the leaf surface. Later they turn brownish 
or black, due to the death of the injured leaf cell-, lo-e much of their 
thickness, and some may become somi what shrunken. Figure 2 illus- 
trates a gall on pear leaf a- seen in cross-section, the normal structure 
being shown at //..• <> i- tin' opening to the interior of the gall and < 
designates eggs of the mite. A cro — ection of one of the dried-up 
galls i- shown in figure 3. 
i"i.. 2 1 :if null. In cr oss section, of leaf 
blister mlti nlng ->f sail : ■ 
• if miii'; 11. normal itruclure of leaf. 
1 a ft it Boraner | 
Fig. ". — SectloD of leaf, showing structure of gall of ''l i-t.-r mite In autumn: <;. OaU; o. 
opening of gall' (After Comstock.) 
On pear, the galls occur more along each side of the midrib of the 
leaf and on apple at the base of, and along the margins of the leaf. 
When numerous, however, the spots will merge together, forming 
large patches or hands of variable size, often involving most of the 
leaf. When thus abundant the leaves may become more or less rup- 
tured and wrinkled, and in the case of the apple the margins may 
curl up. showing the underside. Leaves badly infested are likely 
to fall prematurely, resulting al-o in the dropping of the fruit from 
clusters with wor-t injured foliage. The fruit and fruit --tenis of 
both apple and pear are al-o attacked, the light-colored pimple- 
