A: These plants are showing bagworm damage, as well as actual young bagworms. Damage usually starts being noticeable around Memorial Day, although the critters have been showing up a little early for many of us this year. Plants to watch out for primarily are junipers of all sorts (including Eastern red cedars), Indian hawthorn, and roses, but they can feed on many different plants. Bagworms can be hard to see, particularly on junipers, because the foliage they camouflage themselves with remains green for a while after the pest has chewed them off the host plant.
If your junipers start to thin without explanation, or you see the damage in a more visible fashion on other shrubs, spray the plants with one of several pesticides. We generally prefer spinosad (Captain Jack’s Deadbug Brew) which gives strong control with a much safer pesticide. If your plants were victimized last year, and you don’t see damage yet, consider drenching the plants with Bonide Tree & Shrub drench, which will make the whole plant deadly to the chewing pests.
It’s early in the bagworm cycle, which makes this the perfect time to get them under control. You must treat while the pests are feeding; when they’ve done their dirty work and tied off on the plant to pupate this season, it will be too late to do so.
Bagworm Leaf Damage
Burton specializes in diagnosing and solving plant problems. If you have a question for Burton, please email him at firstname.lastname@example.org and include photos showing the problem.