Webbing and leaf yellowing on boxwoods - Ask Extension
Hi are these spider mites or something else. And if so what should I do to treat them. Everything looked fine but in the last week I have a ton of t...
Knowledgebase
Webbing and leaf yellowing on boxwoods #876163
Asked July 06, 2024, 11:17 PM EDT
Hi are these spider mites or something else. And if so what should I do to treat them. Everything looked fine but in the last week I have a ton of these webbing spots and very yellow dying leaves on my 15 year old box woods
Oakland County Michigan
Expert Response
This is damage from box tree moth. This invasive species is established throughout Oakland County, and the caterpillars cause chewing damage on leaves.
If you do nothing, the tree may continue to decline if the caterpillars are still present. An insecticide with an active ingredient that includes a pyrethroid (see list here: https://www.canr.msu.edu/resources/insecticide-options-for-box-tree-moth-management-ir4-project) can be sprayed once this season or you can use Bacillus thuringiensis every 2 weeks to protect the bush for the season.
If you do nothing, the tree may continue to decline if the caterpillars are still present. An insecticide with an active ingredient that includes a pyrethroid (see list here: https://www.canr.msu.edu/resources/insecticide-options-for-box-tree-moth-management-ir4-project) can be sprayed once this season or you can use Bacillus thuringiensis every 2 weeks to protect the bush for the season.
Thank you.
