Forest Tent Caterpillar Moth - Outbreaks

Outbreaks

The caterpillars are considered a problem when their baby populations explode in the cold fall. They can completely consume a tree. The trees re-foliate quite quickly (within two weeks to a month) and produce enough new leaves to carry on photosynthesis. Under most circumstances, little lasting damage is caused to the trees; however the disappearance of foliage is an eyesore and can be an agricultural nuisance. On those rare occasions when infestations last for three years or more, significant levels of tree mortality will begin to emerge during the years following outbreak collapse. Large-scale tree mortality has been reported in only one instance, in northern Ontario, Canada, after two outbreak cycles in the early and late 1990s occurred back-to-back, resulting in more than six consecutive years of aspen defoliation in some areas.

One outbreak in upstate New York and Vermont began in 2002, with 650,000 acres (2600 km²) defoliated in New York and 230,000 acres (930 km²) in Vermont in 2005.