THE PEAR LEAF-WORM. 5 
changes to light brown and the wrinkles disappear as the body fills 
out. After the second molt the average length is about6 mm. The 
head appears green and toward the end of the instar is lightly dotted 
with small brown spots. The folds or wrinkles in the cuticle and 
sutures appear as white stripes and spots. The length after the third 
molt is 9.2mm. While at first the larva is similar in appearance to 
the preceding instar, the color later is bluish green with whitish 
lateral and dorsal stripes, due to the folds of the skin. These whitish 
stripes disappear at maturity, when the folds have become filled out. 
By the time the larva has cast its first skin (on the average 54 days 
aiter hatching) it has eaten a hole with average diameter of 3.8 mm. 
After the second molt (on the average 84 days after hatching) it has 
eaten out an area of about 12 mm. diameter. Four larve were found 
to have eaten during their larval existence 514, 241, 280, and 416 sq. 
mm. of leaf, respectively, the first of these having consumed somewhat 
more than one-fourth of an average-sized pear leaf (Bartlett). 
Tt was found that a considerable percentage of larvee died at the time 
of their emergence because they were unable to cut their way through 
the eggshell or through the leaf. Also during the first instar there 
was considerable mortality due to unknown causes. During the 
operation of molting numbers fall to the ground, because the larva 
retains only a precarious foothold at this time and is easily shaken or 
knocked off. 
The width of a strip of leaf eaten by the larva during one of its 
circular trips around the hole is equal to three-fourths the height of 
its head. It eats as far as it can reach forward without advancing. 
The head of the larva is always closely in contact with the leaf, filling 
up the place of that portion eaten away, as does also its body, which 
lies at full length along the edge of the hole (fig. 1, 6). It is for this 
reason that the edge of the leaf, defining the hole, appears to be an 
uninterrupted line, and the larva, being almost the color of the leaf, 
is not readily detected without close examination, but its presence 
is made known by the characteristic circular holes that it cuts in the 
leaves. In feeding the larva holds the posterior end of the body 
either straight along the edge of the opening or curled about it, and 
eats around and around the hole, which becomes gradually larger. 
Where the larve are numerous and two or more feed on the same leaf 
they may soon consume it entirely, whereupon they migrate to other 
leaves and commence feeding on the edges (fig. 1, a), as they are 
unable to eat through the flat surfaces. The larve feeding along the 
edges of the leaves on the lower part of the tree are mostly those 
which drop down from above, being dislodged at the time of molting 
or from some other cause. While migrating along the leaf petioles 
or the edges of the leaves the posterior part of the body is carried in 
