_Eudemis botrana_ (S.V.)
The moths emerge and fly early in June, and are quite small,
measuring, when the wings are expanded, only two-fifths of an inch,
Fig. 23, a, enlarged. The fore wings are purplish or slate brown from
the base to the middle, the outer half being irregularly marked with
dark and light brown.
[Illustration: FIG. 23.]
These insects are two-brooded and the first brood feeds not only on
the leaves of the grape, but on tulip, sassafras, vernonia and
raspberry. The caterpillars of the second brood emerge when the grapes
are nearly grown, and bore in them a winding channel to the pulp,
continuing to eat the interior of the berry till the pulp is all
consumed, Fig. 23, d, when, if not full grown, they draw one or two
other berries close to the first and eat the inside of those.
The mature caterpillar, Fig. 23, b, measures about half an inch in
length, is dull greenish, with head and thoracic shield somewhat
darker; the internal organs give the body a reddish tinge. It then
leaves the grape and forms its cocoon by cutting out a piece of a
leaf, leaving it hinged on one side; then rolling the cut end over,
fastens it to the leaf, thus making for itself a cocoon in which to
pupate. The pupa is dark reddish brown.
The second generation passes the winter in the pupa state, attached to
leaves which fall to the ground; therefore, if all the dead and dried
leaves be gathered in the fall and burned, also all the decayed fruit,
a great many of these insects would be destroyed. As the caterpillars
feed inside of the berry, no spraying of the vines with poisons would
reach them. The caterpillar makes a discolored spot where it enters
the berry, Fig. 23, c. Therefore the infested fruit may be easily
detected and destroyed.
There is a small parasite that attacks this insect and helps to keep
it in check. The insect has been known in Europe over a hundred years.
It is not certain when it was introduced into America, but it is now
found from Canada to the Gulf of Mexico, and from the Atlantic to the
Pacific Ocean.