(Lasiocampidae)
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| Forest
Tent Caterpillar (Malacosoma
disstria)
(Lasiocampidae) |
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| Life cycle of the forest tent caterpillar: Top, left to right: Newly deposited egg mass covered with spumaline, Egg mass with spumaline removed, First instar caterpillars, Bottom: Fourth instar caterpillars (left), fifth instar caterpillar (right), Cocoon wrapped in leaf, Adult moth. | ||
The
forest tent caterpillar is broadly distributed
throughout
North America. As with all tent caterpillars, there is just
one generation each year. The egg mass of the caterpillar is the
overwintering stage. Eggs hatch and the first of the five larval
instars appears in
the early spring just as the buds of the host tree are begining to
expand. The caterpillars grow rapidly and after feeding for about
2 months, spin cocoons and pupate. About 3 weeks later the adults
appear and shortly thereafter the moths lay their eggs and die.
Right: Inner cocoon impregnated with yellow crystals of calcium oxylate, and pupa. |
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The forest tent caterpillar is polyphagous but prefers to
lay its eggs on particular trees. In the Northeast, the favored
ovipositional hosts are sugar maple and red oak. However,
the caterpillars frequently leave their natal tree and consume the
leaves of many other species of hardwood trees. One exception is
the red maple, which is not attacked by the caterpillars and is one of
the few trees to remain foliated during outbreaks.
This
is the only tent caterpillar that does not build
a tent. The caterpillars aggregate on pads of
silk spun on leaf
and
bark surfaces. The larvae are nomadic, frequently abandoning a
resting
site, or biovouac, in favor of another. Frequent movement is most
ofter related to foraging and thermoregulation. Caterpillars launch
forays
in search of food from a bivouac, laying down exploratory trails.
The
first caterpillars to finish feeding typically move away from the
feeding
site and establish a new bivouac. The newly fed caterpillars lay
down
recruitment trails which serve to guide the remainder of the colony to
the
new bivouac. Forest tent caterpillars appear to use the same
trail
pheromone
as the eastern tent caterpillar and they are occasionally found camping
out
on the tents of the former.
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| Seven forest tent caterpillars resting
on the
tent of the eastern tent caterpillar |
April 17 Eggs hatch
May 1
Leaf flush on sugar maple
June 16 Caterpillars begin to spin cocoons
July 3 First moths emerge and begin to oviposit
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