Farmers’ Bulletin 1270. 
On 
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APPLE LEAF SKELETONIZER.* 
In the Mississippi Valley States the apple leaf skeletonizer is at times the 
cause of important injury to young orchards (fig. 100) and to nursery trees. 
The caterpillars feed on the upper side of the leaves, protected by a web of 
silken threads. They skeletonize the leaves, eating out the soft leaf tissue, 
the injury giving the foliage a brown, dry appearance. This insect is un- 
doubtedly native and occurs rather generally over the United States east of 
the Rocky Mountains. Its principal food plant is the apple, but occasionally it 
attacks the quince and plum. 
It passes the winter in the pupa stage in cocoons among the fallen leaves, the 
moth appearing during the following May and June. This is a small, pur- 
plish brown insect, with two silvery gray bands across each forewing. The 
forewings have an expanse of nearly half an inch. The larva (fig. 101) is pale 
brownish or greenish, about half an inch long, with four shiny tubercles on the 
back behind the head. There are two broods of larvee each year, the first dur- 
ing midsummer and the second in the fall, the last brood changing to pup 
with the coming of cold weather. 
This insect will readily yield to thorough spraying of the foliage with 
arsenate of lead at the usual strengths. ‘ 
APPLE LEAF-SEWER.” 
The presence in orchards of the apple leaf-sewer, sometimes called the apple 
leaf-folder, is indicated by the occurrence of leaves folded, as in figure 102, often 
exhibiting a somewhat scorched appearance and with the upper parenchyma of 
the leaves more or less consumed. This insect only occasionally attracts atten- 
tion, usually in unsprayed or neglected orchards or on young apple or nursery 
trees that do not receive arsenical sprays. It is a native insect and is confined 
principally to the eastern half of the United States and to certain districts of 
Canada. The apple appears to be thg only plant upon which it subsists, though 
it is probable that it feeds upon wild crabs and other plants related to the apple. 
The insect hibernates as a larva (fig. 105) within the folded leaves that have 
fallen to the ground. At this time it is about half an inch in length and light 
gray; the head is yellow with a somewhat darker thoracic shield, bearing a 
black spot on each side. In the spring the larvee change to brownish pup, 
from which the moths issue. The adult, or moth (fig. 104), is white, with mark- 
ings of brown, and the wing expanse is about three-fourths of an inch. The 
small, flat, oval, yellow eggs are placed on the foliage and are usually securely 
glued to the under surface of the leaf. Upon hatching, the larva spins a silken 
web on the lower leaf surface, where it begins eating the parenchyma, gradually 
folding over as it grows a portion of the lower side of the leaf. After feeding 
awhile in this somewhat restricted area, it eats its way through the upper fis- 
sues and migrates to a near-by leaf, where it begins another web on the lower 
leaf surface and fastens together the opposite halves of the leaf. The leaves 
are folded in this way until the larva completes its growth, and thus a single 
caterpillar will often injure several leaves. The larva remains through the 
winter within the last leaf attacked, in the fallen leaves on the ground. 
In orchards regularly sprayed for the codling moth this species will require 
no specific treatment. Where for any reason special applications are necessary, 
arsenate of lead should be used at the usual strength for caterpillars of this 
character, The raking together and burning in early spring of fallen, infested 
leaves may also be advisable, if the insect is particularly abundant. 
*% Canarsia hammondi Riley. *® Ancylis nubeculana Clemens, 
