Bagworms, found east of the Rockies, plague evergreens and other plants. Spray or handpick bags NOW. Eggs are hatching in those leather-like bags hanging on your evergreens. Larvae crawl out and feed on foliage, slowing destroying your beautiful plant in the process. Then they create their own "bag". Once they seclude themselves inside, they are impervious to any spray you apply.
How do you eradicate them? Spray or handpick bags RIGHT NOW. Spray the entire plant with malathion or check your local garden shop for another good product. If you are hesitant to use chemicals, then your next best method is to handpick and destroy the bags or spray with BTK, a microbial biological control (ask for it at your garden store).
If you choose to handpick the bags, use a knife or hand pruners to cut the silk from the twig. if you tear the bag off, you leave a coil of tightly wound silk. It will girdle the twig and cause a different problem.
If the bags are left on your plant, the caterpillars will slowly defoliate the plant, weaken it, and in a couple of seasons, or so, the plant will die.
Be aware that bagworms are not limited to evergreens. They will eat foliage from any plant and use it to create bags. So if you find them in evergreens, check every tree and shrub in your landscape. Vigilance is key in eradication and protecting your beautiful plants spring after spring.
