What is infecting and destroying my evergreen hedge? - Ask Extension
Something, presumably some kind of insect, is attacking my evergreen hedge and is doing some serious damage. Can you tell me whatit is and what can ...
Knowledgebase
What is infecting and destroying my evergreen hedge? #809480
Asked September 05, 2022, 11:26 AM EDT
Something, presumably some kind of insect, is attacking my evergreen hedge and is doing some serious damage. Can you tell me whatit is and what can be done about it? Thank you in advance for any advice you can provide.
District of Columbia County District of Columbia
Expert Response
Unfortunately the photos are too small for us to enlarge to see more clearly, but if the silken brown-gray bags we see in one of the photos are recent (from this year), then a Bagworm infestation has consumed foliage. These caterpillars are very common and prefer to feed on evergreen foliage like Arborvitae and Juniper. You can visit our Bagworms on Trees and Shrubs page to learn more about this insect.
It is probably too late to do anything about the caterpillars right now as bagworms are either finished or nearly finished feeding. (They must consume treated foliage in order for a treatment to work, because the bags they shelter in protect them from direct sprays.) You can pick or snip off any visible bags and squish them, and monitor the plants for them next summer as new larvae begin to hatch and feed. Then, treatment with a lower-risk pesticide, such as those using the active ingredients Bt (for caterpillars) or spinosad, before they grow too large, should help control them.
Arborvitae do not regrow lost foliage, so any individual plants with too many bare twigs might need replacing. Otherwise, branches that still have foliage will start to regrow and cover-up bare areas next year.
Miri
It is probably too late to do anything about the caterpillars right now as bagworms are either finished or nearly finished feeding. (They must consume treated foliage in order for a treatment to work, because the bags they shelter in protect them from direct sprays.) You can pick or snip off any visible bags and squish them, and monitor the plants for them next summer as new larvae begin to hatch and feed. Then, treatment with a lower-risk pesticide, such as those using the active ingredients Bt (for caterpillars) or spinosad, before they grow too large, should help control them.
Arborvitae do not regrow lost foliage, so any individual plants with too many bare twigs might need replacing. Otherwise, branches that still have foliage will start to regrow and cover-up bare areas next year.
Miri
