PRESS BULLETIN 209
May 3, 1913
UNIVERSITY OF FLORIDA
AGRICULTURAL EXPERIMENT STATION
MELON WORM AND PICKLE WORM
By J. R. Watson
These two insects did much damage in Florida last season, and are
again active. In spite of their common names, either or both of them
may be found on cucumbers, or canteloupes, as well as gourds and squashes.
They seldom attack water-melons. Their habits differ somewhat, and con-
sequently the remedies to be applied.
The pickle worm is the more common of the two. It never eats the leaves,
but bores into the buds, blossoms, stems, and leaf-stalks, as well as into the
fruits, which it utterly ruins. The melon borer does not often bore into the
vines or leaf-stalks, but eats its way into the fruits, and also feeds ex-
tensively on the leaves.
The melon worm, because it feeds partly on the foliage, can be reached
by arsenical sprays. Use three pounds of lead arsenate paste to fifty gal-
lons of water, or use one-half as much of lead arsenate powder, or one pound
of zinc arsenite to fifty gallons. Paris green may be used at the rate of
one-half pound with one pound of freshly slaked lime to fifty gallons of
water, but it does not stick as well as the others and is more liable to
burn the foliage.
The pickle worm, because it feeds in the interior of the buds, blossoms,
and fruits, cannot be reached by arsenical sprays. The grower should care-
fully collect and destroy all wormy fruit with the contained worms. If these
wormy cucumbers and melons are left in the field, the caterpillars will enter
fresh ones, or complete their growth and enter the ground, to emerge as
moths in a week or two. The moth lays enough eggs to hatch into about ,
three hundred more worms.
The easiest and most successful remedy for both of these worms is a
trap crop. For this purpose plant, for each acre of cucumbers or canta-
loupes, from four to eight rows of early summer or crook-necked squash.
The large blossoms and leaves, and the tender fruits of this plant are pre-
ferred by the moths to either cucumbers or melons, and most of the eggs
will be laid on the squash. It is better to make several plantings of the
latter so as to have a succession of attractive blossoms and fruits to invite
the moths. The first planting should be made at the same time as that of
the cucumbers or melons, and other plantings at intervals of a week. One
may pick off the infested squash blossoms and fruit and destroy them; and
also, if the melon worm is abundant, spray the vines with one of the arsenicals.
The quickest way, however, to destroy the pests on the trap crop is to pull
up and burn each lot of trap plants as soon as it has become thoroughly in-
fested and before the worms have attained their full size. If this is neglected,
the trap crop is useless.
Clean culture should be practiced, not only on account of these insects,
but also to keep down fungus diseases. As soon as the grower is through
picking, the vines, fallen leaves, and other refuse should be raked up and
burned. Also, if practicable, do not plant cucumbers or melons on the same
land two years in succession.
Description and Life History
The pickle worm (Diaphania nitidalis) is a whitish caterpillar, with con-
spicuous black dots on each segment. When nearly full grown these spots
become less conspicuous, and the worm is of a coppery color. The melon
worm (D. hyalinata) lacks these dark dots, but has longitudinal stripes and
never become coppery colored. It takes about two weeks to complete
its growth, and then forms a cocoon in a dry leaf on or near the plant which
nourishes it. Here it remains about a week and then issues as a moth. The
moth of the pickle worm is from an inch to one and a fourth inches across
the out-stretched wings, which are white with a broad black border. It lays
its eggs mostly on the buds and in the flowers. The melon-worm moth is
larger, about one and three-fourths inches across, and the white area on the
wings is much larger, occupying all but a narrow margin. It lays its eggs
mainly on the tender young leaves. The eggs of both moths hatch in three
or four days.
State papers please copy.