Insect
and Disease Fact Sheet Compliments of New Century
1-877-79TREES
Eastern & Forest Tent
Caterpillars
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Nests
or tents of the eastern tent caterpillar are a common sight in along fence
rows and in homeowner trees in many parts of Ohio during the spring months.
Its close cousin, the forest tent caterpillar, doesn't make a tent at all
though the caterpillar may be common in wooded areas. Both caterpillars are
commonly mistaken for gypsy moth larvae by home owners or wood lot managers. The
eastern tent caterpillar makes its nest in the fork of branches and does not include leaves
like the fall webworm. Tent caterpillars are generally active until early
June. Both
tent caterpillars are found across Ohio but the forest tent caterpillar is
most common in the eastern half of the state. |
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Plants Attacked The
eastern tent caterpillars prefer wild cherry along roadways, but it can be
found making nests in ornamental apple, crabapple, plum, peach, and cherry in
landscapes. Occasionally it will form nests in ash, birch, willow, maple, oak
and poplar. The favorite food of the forest tent caterpillar is also wild
cherry but oaks, maples, hawthorns, and many other shade and forest trees may
be attacked. Damage One
or two colonies can completely defoliate small trees. Periodic, major
outbreaks result in numerous colonies in larger trees which can also do
considerable defoliation. Since this defoliation occurs early in the season,
the plants must set out new leaves at considerable energy expense. |
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Besides
making a tree look unsightly with the webs it constructs in the crotches of
limbs and branches, the caterpillars arouse much concern among area residents
when they migrate in mass in search of new food or a place to complete their
development. During periods of migration, caterpillars may be seen by the
thousands traveling over roads, streets, driveways, and sidewalks. .
Description and Life Cycle
The
eastern tent caterpillar is easily identified when it builds its white silk
nest in the crotch of small trees or where several limbs meet on larger trees.
Eastern and forest tent caterpillars have thick, tan hair and are black in
color with irregular blue and white mottling. Some of the white markings define
stripes. The eastern tent caterpillar has diagnostic solid white stripe down
the back while the forest tent caterpillar has a series of keyhole-shaped
spots.
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Tent
caterpillars over winter in the egg stage. Egg masses are attached to small
twigs and appear as shiny, dark gray foam rapped around the twig. These
masses are about one inch long and contain 150 to 350 eggs. The eggs hatch in
early spring just as the leaf buds begin to show green. The tiny black
caterpillars sun themselves on the egg mass but soon have to move to a nearby
fork in the branches. Here they begin to spin silk and form a tent. The
larvae migrate to the new leaves to feed, usually in the morning or early
afternoon. After feeding the larvae return to the nest. The larvae lay down
silk trails wherever they go and these trails serve as roadways for other
larvae. Feeding continues for four to six weeks until the larvae are about
two inches long. Mature larvae usually leave the nest and tree to search for
a suitable place to spin a cocoon. The larvae spin compact, spindle shape
cocoons of white to yellow silk. The adults emerge in two to four weeks. The
adults are about one inch long, are reddish brown in color and have two
creamy- white stripes running obliquely across the front wings. Forest tent
caterpillars do not make a nest and the adults moths' have dark brown stripes
instead of white. Mating occurs soon after emergence and the females attach
their new egg masses to tree branches. These masses stay on the tree until
the following spring. There is only one generation per year. |
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Control Hints
People
often get overly concerned when they see large numbers of nests in roadside
wild cherry. Fortunately these pests rarely reach large populations in
ornamental trees.
Strategy 1: Mechanical Control -
Destroy Egg Masses and Nests - The egg masses are easy to spot after the leaves have
dropped in the fall. Simply clip off and crush or dispose. If egg masses were
undetected, there is ample time to hand remove any nests in the spring. It is
suggested that a glove be used as the caterpillar hairs are irritating to some
people. Simply scrape the nest off onto the ground and crush the caterpillars
or drop them into a pan of soapy water. Early morning or late afternoon is best
because most of the caterpillars will be in the tent.
Strategy 2: Biological Control-
Use Bacillus thuringiensis (Bt) - Most commercial Bt products
for caterpillar control will work on the tent caterpillars. Make applications
to the plant foliage while the larvae are small. Numerous predators and
parasites also attack this pest but in some years these agents did not arrive
in sufficient numbers to adequately control tent caterpillars.
Strategy 3: Chemical Control-
Insecticide Sprays-
Most contact and stomach insecticides rapidly control this pest. Direct sprays to the plant foliage and nest.
Information obtained through the Ohio State University
Extension Factsheet HYG-2022-95
Insect
and Disease Fact Sheet Compliments of New Century
1-877-79TREES