_Clisiocampa Americana_ (Harr.)
Large, white, silken web-like tents, Fig. 15, are noticed by the
roadsides, in the early summer, on wild cherry trees, and also on
fruit trees in orchards, containing numerous caterpillars of a
blackish color, with fine gray hairs scattered over the body.
This well known pest has been very abundant throughout the State for
several years past, and the trees in many neglected orchards have been
greatly injured by it, some being entirely stripped of their leaves.
The trees in these orchards and the neglected ones by the roadsides
form excellent breeding places for this insect, and such as are of
little of no value should be destroyed. If this were well done, and
all fruit growers in any given region were to destroy all the tents on
their trees, even for a single season, the work of holding them in
check or destroying them in the following year would be comparatively
light.
[Illustration: FIG. 15.]
The moths, Fig. 16, appear in great numbers in July, their wings
measuring, when expanded, from one and a quarter to one and a half
inches or more. They are of a reddish brown color, the fore wings
being tinged with gray on the base and middle, and crossed by two
oblique whitish stripes.
[Illustration: FIG. 16.]
The females lay their eggs, about three hundred in number, in a belt,
Fig. 15, c, around the twigs of apple, cherry, and a few other trees,
the belt being covered by a thick coating of glutinous matter, which
probably serves as a protection against the cold weather during
winter.
The following spring, when the buds begin to swell, the egg hatch and
the young caterpillar seek some fork of a branch, where they rest side
by side. They are about one-tenth of an inch long, of a blackish
color, with numerous fine gray hairs on the body. They feed on the
young and tender leaves, eating on an average two apiece each day.
Therefore the young of one pair of moths would consume from ten to
twelve thousand leaves; and it is not uncommon to see from six to
eight nests or tents on a single tree, from which no less than
seventy-five thousand leaves would be destroyed--a drain no tree can
long endure.
As the caterpillars grow, a new and much larger skin is formed
underneath the old one, which splits along the back and is cast off.
When fully grown, Fig. 15, a and b, which is in about thirty-five to
forty days after emerging from the eggs, they are about two inches
long, with a black head and body, with numerous yellowish hairs on the
surface, with a white stripe along the middle of the back, and minute
whitish or yellowish streaks, which are broken and irregular along the
sides; and there is also a row of transverse, small, pale blue spots
along each side of the back.
As they move about they form a continuous thread of silk from a fleshy
tube on the lower side of the mouth, which is connected with the
silk-producing glands in the interior of the body, and by means of
this thread they appear to find their way back from the feeding
grounds. It is also by the combined efforts of all the young from one
belt of eggs that the tents are formed.
These caterpillars do not feed during damp, cold weather, but take two
meals a day when it is pleasant.
After reaching their full growth, they leave their tents and scatter
in all directions, seeking for some protected place where each one
spins its spindle-shaped cocoon of whitish silk intermingled with
sulphur colored powder, Fig. 15, d. They remain in these cocoons,
where they have changed to pupæ, from twenty to twenty-five days,
after which the moths emerge, pair, and the females lay their eggs for
another brood.
Several remedies have been suggested, a few of which are given below.
Search the trees carefully, when they are bare, for clusters of eggs;
and, when found, cut off the twigs to which they are attached, and
burn them.
As soon as any tents are observed in the orchard they should be
destroyed, which may be readily and effectually done by climbing the
trees, and with the hand protected by a mitten or glove, seize the
tent and crush it with its entire contents; also swab them down with
strong soapsuds or other substances; or tear them down with a rounded
bottle brush.
Burning with a torch not only destroys the caterpillars but injures
the trees.
It should be observed, however, since the caterpillars, are quite
regular in taking their meals, in the middle of the forenoon and
afternoon, that they should be destroyed only in the morning or
evening, when all are in the tent.
Another remedy is to shower the trees with Paris green in water, in
the proportion of one pound to one hundred and fifty gallons of water.