These unsightly nuisances are not harmful to humans or pets. Also they do not do any lasting damage to trees or foliage.
These caterpillars use pheromones to mark off trails on host trees. They also live in close quarters in tents to keep each other warm during chilly spring nights.
If wanted they can be removed by any product with BT in it.
*BT is Bacillus Thuringiensis
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