This is the worm that the amateur and the very busy man suddenly
discovers in April defoliating his apple trees, and, on examination, he
finds them in such myriads that he imagines some power has suddenly sown
them broadcast over his orchard. See fig. 1. Had he been observant
during the sunny middays of February, he would have noticed insects
similar to figure 2 crawling up the bole of the tree, and looking closer,
a little later, he would see small masses of eggs, shown in figures
3 _a_ and _b_, glued fast, usually near the base of limbs or twigs.
[Illustration: FIG. 1.]
[Illustration: FIG. 2. Adult Female.]
[Illustration: FIG. 3. _a_, Eggs deposited at base of limb. _b_,
Egg mass.]
[Illustration: FIG. 4. _a_, Larva, or worm. _b_, Cluster, and
a magnified egg.]
Along early in April these eggs, warmed by the same sun that swells the
buds and causes the green tips of the leaves to protrude, hatch into
tiny worms looking like a dark thread snipped into bits about an eighth
of an inch long. These millions of tiny worms, scarcely visible, occupy
their time eating and growing, and the orchardist is possibly unaware of
the army he is feeding until they grow into lusty, fat worms, from one
and one-eighth to one and one-fourth inches long, of a dark olive-green
color, with black heads. See _a_, fig. 4. If disturbed they quickly spin
a single web and fall suspended at its end, as in fig. 1. Their life, as
worms, lasts only about six weeks, then they seem suddenly to have
vanished. They have gone into the earth to pass into the pupa state,
coming out the following spring as adults; the males with wings to fly,
the female wingless, as in fig. 2, to crawl up the tree as described.
Now, as these myriads of tiny worms must make the tons of grown worms
entirely from the foliage on the trees in which they hatched, it is
plain that the said foliage must suffer, and it will look as if scorched
by fire.
_Remedies._ Bands smeared with sticky material put tightly around the
tree bole early in February has stopped many a female from crawling up
to lay her eggs. Spraying with London purple or Paris green, one pound
with two pounds of lime and 150 gallons of water, is the common remedy.
To be efficacious the drug must be of a normal strength, say forty-five
per cent. arsenic, and as the worms grow larger and stronger the water
must be lessened. When the worms are an inch or more long it may require
only fifty gallons of water. Another formula is, two pounds white
arsenic, four pounds sal soda, two gallons of water; boil until the
arsenic is dissolved. One pint is enough for forty gallons of water. As
the worms usually feed on the under side of the leaves, spraying should
be from below as much as possible. "The early bird catches the worm" is
true here. Therefore, spray while the worms are tiny and the foliage
thin, and the work will count as the "stitch in time," destroying nine
hundred and ninety-nine.