ROTHWELL LANDSCAPE: Bagworms will munch on just about anything green.  However, they are most damaging to evergreens because once an evergreen is completely defoliated it will not leaf out again, whereas a deciduous shrub/tree will.  It is very stressful to a deciduous tree/shrub to have to leaf out a second time in the same season which weakens it making it more susceptible to other stressors such as drought, diseases, and other pests.  When we treat for bagworms we will also treat any shrubs in the maintained landscape we see them on because they do migrate during the season meaning that if only the infested evergreens were treated they could become re-infested from an infested deciduous tree/shrub.  It is important to keep any eye out during the rest of the season as it is possible they could migrate from nearby areas such as neighbor’s yards or unmaintained wooded areas.  About a week after an application is made you can check to make sure the bagworms are dead (they securely attach their bag homes to branches so even once they die the bags will not fall off the plant) by using the “squish” method.  By this I mean pull some bags off and squish them to see if they are still “juicy”.  Hey, a beautiful landscape comes with a little “YUCK”.