If you have arborvitae, junipers, cypress, spruce, cedar, or other evergreen shrubs and trees, now is the time to start checking for bagworms. These destructive pests begin as tiny caterpillars that feed on foliage and quickly build the familiar “bags” that hang from branches. Left untreated, bagworms can strip plants of their foliage and cause severe damage—especially to evergreens.