If its bagworms kill them all.
http://blog.davey.com/2018/04/bagworms-are-they-harmful-and-how-can-i-get-rid-of-them/What damage do bagworms do?
Bagworms will attack more than 120 different types of trees. Though, they prefer evergreens, like juniper, arborvitae, cedar and spruce.
Once they’ve found a tree to call home, bagworms start munching.
On evergreens, they’ll eat lots of the buds and foliage, causing branch tips to turn brown and then die. But if they eat more than 80 percent of the tree, the entire evergreen may die.
On deciduous trees (those that lose their leaves in winter), bagworms chew small holes in the leaves and can cause defoliation. Generally, these trees will bounce back if you get rid of the bagworms.
Bagworms also wrap silk around the twigs they build their bags on, which could kill the tree twigs a few years from now.