Bag worms eating Arborvitae HELP!

Asked August 1, 2016, 12:29 PM EDT

I'm new to home ownership and confess I have t been watching my plants as closely as I should. I had noticed recent damage to my front arborvitae but chalked it up to heat. Yesterday I took a closer look and noticed it's being eaten by bag worms. And they're moving to a couple surrounding plants including rose bushes. I see that spraying them is best when they're younger. But I need to do something! What would you recommend? Also, will the eaten/damaged portions recover? Any help is greatly appreciated.

Wicomico County Maryland bagworms arborvitae trees

1 Response

Bagworms are insects that require control as they can defoliate evergreens and sometimes deciduous trees/shrubs. If you can reach the bagworms, handpick as many as you can now and drop into a bucket of soapy water and remove any from the ground as they can complete their life cycle. Dispose of in soapy water and remove any bagworms from the ground as they may be able to complete their life cycle. If you cannot handpick or multiple trees are involved, you will have to spray. A biological control, Bacillus thuringiensis, often called Bt, is a type of bacteria that only kills certain insects and does not affect humans or animals. Bt must be applied between mid-June and mid-July because it works well only on young bagworms. If the bagworms are larger than an inch you can spray with spinosad.
If your trees are too large to spray, contact a certified arborist as they have the materials to do the job. Scratch the branches with your fingernail and look for green tissue. If you see it, the branches may still be viable and you may see some new growth next year. A branch cut back to a non leafy region will not form new foliage. They can be slow to put out growth. If the plants are in a prominent section of your landscape, you may decide to replace.
Next season handpick as many as you can during the winter and before the eggs hatch in June and discard.
See our website for more information on bagworms http://extension.umd.edu/hgic/bagworms-trees-and-shrubs
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