insect problem - Ask Extension
I have a pest problem that I first notice in some boxwoods 2 years ago. Those plants died. Sprayed area with malathion and haven't replanted there. T...
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insect problem #926648
Asked March 24, 2026, 12:24 PM EDT
I have a pest problem that I first notice in some boxwoods 2 years ago. Those plants died. Sprayed area with malathion and haven't replanted there. This past summer it seems to have infected all of the evergreen shrubs around all sides of the house, and a lilac.
There is a very fine spider web-like substance in all the affected plants. Insects are not visible, but I do have access to a microscope if you could advise me.
I'm reluctant to plant anything else to replace the dead plants until this is resolved. I hate to use insecticides but maybe there is a time or method that could minimize damage to bees and other insects.
Any ideas greatly appreciated! Thank you.
Muskingum County Ohio
Expert Response
Thanks for contacting Ask Extension
There are a few common problems that are very often found with boxwoods, that I will try to address. But first and before advising you to use a pesticide it is best to try to identify the specific cause. There are many insects that can cause a problem, but most often a boxwood mite is found to be the problem.
Hold a sheet of white paper under a branch and tap or shake the foliage. If you see any tiny moving specks, it strongly suggests mites. Crush the speck and see if it leaves a green/brown smear. It may be a mite. Spider mites are more likely to flare up when plants are heat or drought -stressed and and broad-spectrum insecticides can sometimes worsen mite issues by disrupting natural enemies.
Because you expressed concern over spraying insecticide these are some other options:
You might consider taking a small, bagged clipping of the evergreen branch affected into a local nursery and see if they can suggest the cause and best treatment.
I have included a few other articles that might help you to diagnosis the problem
Boxwood: Identify and Manage Common Problems | University of Maryland Extension
Common Insect Pests of Boxwood
Lace Bugs | Ohioline
I hope this information has helped.
Thank you for contacting us
There are a few common problems that are very often found with boxwoods, that I will try to address. But first and before advising you to use a pesticide it is best to try to identify the specific cause. There are many insects that can cause a problem, but most often a boxwood mite is found to be the problem.
Hold a sheet of white paper under a branch and tap or shake the foliage. If you see any tiny moving specks, it strongly suggests mites. Crush the speck and see if it leaves a green/brown smear. It may be a mite. Spider mites are more likely to flare up when plants are heat or drought -stressed and and broad-spectrum insecticides can sometimes worsen mite issues by disrupting natural enemies.
Because you expressed concern over spraying insecticide these are some other options:
- Rinse foliage (a strong water spray) to knock mites/webbing off when practical; repeat as needed (especially on smaller shrubs). (This is consistent with IPM “mechanical control.”) [5]
- Improve plant vigor: reduce drought stress (deep watering when needed), avoid overwatering, and improve airflow with selective pruning. [5]
- If treatment is warranted, consider insecticidal soap or horticultural/dormant oil, which are commonly used against mites with less impact than many broad-spectrum options when applied correctly. For example, guidance for certain evergreen mite pests notes insecticidal soap in late April/early May when mites are active and dormant oil in late winter to smother overwintering eggs (apply before bud break). Bees are not active now and the shrubs have no flower; you need not worry about causing them harm.
Webbing alone is often from spiders ( not causing plant damage)
Decline and dieback on branches can involve specific diseases. Severe cold temperatures like we had this winter can cause damage if the branches are not in full dormancy and the moisture content in the branch is high. Also, Ohio, is watching boxwood threats like box tree moth. so confirming is important. You might consider taking a small, bagged clipping of the evergreen branch affected into a local nursery and see if they can suggest the cause and best treatment.
I have included a few other articles that might help you to diagnosis the problem
Boxwood: Identify and Manage Common Problems | University of Maryland Extension
Common Insect Pests of Boxwood
Lace Bugs | Ohioline
I hope this information has helped.
Thank you for contacting us
