Bagworms pose massive problems if left unchecked, experts say


RALEIGH, N.C. (WNCN) – Ornamental shrubbery on a property may lead to bagworms that can cause damage.

The bagworm is a master of disguise. It makes itself look like a tree branch or pine cone to protect itself and fool predators.

“They are a defoliating insect. They eat leaves,” said Rob Trickle, who is the head of the Forest Health Branch of the North Carolina Forest Service.

The pests attack more than 120 different varieties of trees, but prefer evergreens such as junipers, arborvitae, and the Leyland cypress. If one tree gets too crowded, the worms will just head over to another one, giving rise to reports of “walking pine cones.” The moving cone is actually the caterpillar pulling a protective cocoon with it.

“The more you get on the tree, the more defoliation you will get,” Trickel said.

Bagworms are native to North America. When they are feeding, they can literally suck the life out of an evergreen.

“With a hardwood, it’s not a big deal. It’ll put out a new leaf,” Trickel said. “But, with an evergreen, they won’t put out a new leaf after a leaf has been eaten or killed.”

The infestations usually start small. If left unchecked, it becomes a huge problem. Trickel said the bagworms can reproduce exponentially. They also survive the winter in their protective cocoons, laying hundreds of eggs for the next season.

“It’s a pretty big pest of landscaped trees,” Trickel said.

Although more of a landscape than a forestry problem, the bagworm is still included in the state forestry department’s handbook on pests.

Pesticides can be used to eliminate bagworms, but that has to be done by June when they are feeding at their most energetic rate. Experts say the best way to take care of them is to do it by hand by pulling the sacks off the branches of the infested evergreen.

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