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- [Mark] This is Mark Isselhardt,

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Maple Specialist with the
University of Vermont Extension.

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And this is another Vermont Maple Minute.

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It appears as though the
recent, widespread defoliation

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related to forest tent
caterpillar has ended.

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According to Vermont Department

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of Forest Parks and Recreation,

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there have been no reports of defoliation

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attributed to this native insect in 2019.

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This is in stark contrast

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to the roughly 70,000 acres

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of defoliated trees in 2018.

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The dramatic decrease is typical

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of the boom and bust
cycles previously observed.

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The cycles will last
between two and four years

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in Vermont and occur
roughly every 10 to 20 years

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in some part of the state.

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The caterpillars can multiply rapidly

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and make their presence known

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by consuming large volumes of leaf matter.

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During the outbreak,

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it is not uncommon for
wide areas of forest

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to appear brown and
almost leafless from afar.

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The vast majority of trees
will regrow new leaves

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to make up for the ones
that have been lost.

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In rare cases,

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some individuals have
even been defoliated twice

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in the same summer without dying.

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At the end of an outbreak,

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the caterpillar populations will crash

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as a result of a corresponding increase

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in several natural predators
and natural controls.

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Most trees will recover after a few years

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of poor growth and this
native insect will return

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to relative obscurity
until the next outbreak.

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This has Mark Isselhardt, Maple Specialist

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with the University of Vermont Extension,

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and this has been another
Vermont Maple Minute.