Protect Your Boxwoods from Box Tree Moth in Cincinnati
Box Tree Moth (BTM) caterpillars feed on boxwoods (Buxus) and can defoliate shrubs quickly if left untreated. If you’re in Cincinnati, consistent scouting and fast action are key during the growing season.
What to Know About Box Tree Moth (BTM)
When is BTM active? 
In our region, BTM activity generally ramps up from spring through fall with multiple, overlapping generations. Caterpillars emerge in spring and activity can continue into October.
Common signs of infestation
Look for:
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Chewed or “skeletonized” leaves
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Webbing inside the shrub
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Green caterpillars (often with darker striping)
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Frass (tiny droppings)
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Browning and thinning foliage
How to Protect Your Boxwoods 
1) Inspect weekly (more during warm, humid weather)
BTM damage accelerates fast. Check:
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Deep inside the plant
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Lower branches
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Areas with webbing and leaf debris
2) Treat immediately if you find caterpillars (or confirmed BTM nearby)
Extension guidance recommends treating when an infestation is identified (or in close proximity to a confirmed infestation), rather than spraying “just in case.”
Home-garden treatment options (common retail products):
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Bt(k) (Bacillus thuringiensis kurstaki) — best on small/young caterpillars
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Spinosad — effective across caterpillar stages and can last longer on/within leaves
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Eight® (label varies by product) — follow the label exactly for caterpillars and ornamentals
Available at many garden centers (including Natorp’s, if that’s your store reference).
3) Apply for full coverage (this is where most treatments fail)
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Use a hose-end sprayer, tank sprayer, or ready-to-spray bottle
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Soak leaves and stems thoroughly
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Start deep inside the shrub where caterpillars hide
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Follow all label directions (rate, timing, safety)
4) Recheck quickly, then reapply as needed
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Monitor daily for a few days after treatment
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Many programs call for a follow-up application about 7 days later to improve knockdown when pressure is high (always follow your product label and local guidance)
5) Keep scouting through fall
Continue weekly inspections through October, and restart scouting in April as activity resumes.
Can Boxwoods Recover After BTM Damage? 
Often, yes—if stems are still alive. After the active season, you can rejuvenation prune by cutting stems back (commonly 6–24 inches, depending on plant size and damage) in late fall, winter, or early spring to encourage regrowth.
If Removal Is Needed (Reduce Spread Risk)
If plants are beyond saving:
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Bag and seal infested plant material for disposal
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Avoid moving loose clippings or debris around the yard
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Ask our team about boxwood alternatives that keep the same clean, structured look
Have a Question? Ask Our Plant Experts.
We help homeowners identify BTM damage, choose the right treatment approach, and plan next steps for recovery or replacement.