Bagworms feed on just about any plant but usually favor the evergreens. I suggest looking over your spruce, arborvitae and junipers, which include the eastern redcedars, for bagworms. Scout other plants as well. The ones I’ve seen are already a half inch long.
Hand removal is an option although it could become a tedious task. There are lots of products labeled for controlling bagworms. Bagworms are susceptible to these products, especially when they are young. Controlling them with an insecticide later in the season becomes much more difficult.
Commonly-used insecticides include malathion or spinosad. Some other active ingredient possibilities include the bacteria Bacillus thuringiensis, acephate, bifenthrin, carbaryl, cyfluthrin, deltamethrin, lambda-cyhalothrin, or permethrin. Always read the product label for best results.
More important than what product to use is the application process. Thorough spray coverage is necessary to reduce bagworm populations. Hand pressure sprayers typically don’t penetrate dense foliage of evergreens. They are good at treating the peripheries of the plants. Bagworms often feed deep in the plant.
Powered sprayers or hose end type of equipment are better at treating the whole infected plant. Tall trees may require a commercial applicator to get complete coverage.
The bagworm-preferred plants add interest to the landscape. Evergreens are of particular interest in the winter. I still suggest using them in the landscape. There aren’t any guarantees when working with nature.
Available from the extension office or online is the K-State Research and Extension’s publication, “Bagworms,” to provide additional information.