Continued care of Boxwoods that had BTM - Ask Extension
Hello,
We have two communities we manage the landscaping for that showed up last year with Box Tree Moth. All of the Boxwoods in those two communitie...
Knowledgebase
Continued care of Boxwoods that had BTM #928446
Asked April 15, 2026, 9:38 AM EDT
Hello,
We have two communities we manage the landscaping for that showed up last year with Box Tree Moth. All of the Boxwoods in those two communities were treated: one community only treated in early September and the other had a late summer and early fall treatment (by a separate company that deals with shrub and tree applications) and that seemed to take care of them at that point. Our question is, going into this year, should we plan to do one or more treatments since we had a known infestation, or do we "reset" each year, and not make any additional treatments until we once again confirm the presence of the moth/caterpillars? The application company we used is recommending to plan on 2 treatments this year, but we weren't sure if this counts as preventative, since we treated last year, or due to the multiple life cycles, and especially the one community only having that one late season treatment, if for at least this 1st subsequent year we continue on in "active infestation" mode?
Thank you,
Hamilton County Ohio
Expert Response
I wouldn't assume all the caterpillars were killed last year. Those applications occurred after BTM started producing overlapping generations, meaning that it's likely there were eggs and pupae present that would not have been killed. That's why late-season applications don't work nearly as well as early-season applications.
BTM overwinters as small caterpillars in a kind of stasis called diapause. They have now become active again and are starting to feed. This is the best time of the year to make an application. It can potentially eliminate the infestation.
That's the direction I'd focus on.
