58 
covers, but a few were observed in which the larve had evidently 
emerged through the lower surface of the egg next to the apple or 
leaf. 
The young caterpillar is about one-fifteenth of an inch in length and 
is of a semitransparent color. Later dark spots appear around the 
hairs. 
The young larva, after piercing the apple, makes a shallow mine just 
under the skin. Those mines can be easily recognized by the lighter 
color and by the excrement which is cast out. The larvee which enter 
by the calyx also take their first few meals at the surface inside the 
calyx. 
By counting infested apples on unsprayed trees I found that about 
60 per cent of the larvee of the first brood enter at the calyx end. In 
the later broods but few enter the calyx end. Many enter the apple 
at the stem end. The greater proportion, probably from 60 to 90 per 
cent, enter at any part of the apple. A favorite place of entrance is 
at the point where two apples touch. 
At the end of four or five days the larva commences to tunnel toward 
the central portion of the fruit. Arriving at the center, if commences 
irregular excavations, which are filled with excrement, the pellets of 
which are bound together by silken threads. Surrounded by abun- 
dance of food, the insect grows rapidly, casting its skin many times. 
I have found many burrows, sometimes as large in diameter as a full- 
grown larva, in which no larva could be found; therefore, I believe 
that sometimes a larva feeds upon more than one fruit. In all cases 
where fruits touch they are both injured. 
While one larva usually feeds upon but one apple, one apple may 
be eaten by many larve. A large apple was found with thirteen worm- 
holes in it, both entrance and exit, and three larvee, of various sizes, 
were feeding inside. It is a very common occurrence to find from 
four to seven holes in an apple. These different holes are usually 
made by insects of different broods. In a badly infested orchard the 
earlier apples rarely had but one insect in each, A larval stage of 
from ten to fourteen days, as given by Professor Card, is, I think, 
nearly correct for Idaho. 
On summer apples and most fall apples the effect of the insect is to 
cause the fruit to ripen prematurely. In the winter varieties, such as 
Winesap, there is no such ripening. In all cases the fruit is rendered 
unfit for use. When full grown the larva eats its way to the surface of 
theapple. The burrowis kept closed by frass, or sometimes an adjacent 
leaf is fastened over the hole with silk. Having eaten as much as it 
desires, the larva pushes out the plug or removes the leaf and leaves 
the fruit. In warm weather the worms, for the greater part, leave 
the apples in the early evening or night; but in colder weather, in the 
fall, they emerge during the heat of the day. Ii the fruit has fallen, 
