The Ohio Department of Agriculture (ODA) announced today that the box tree moth (BTM) (Cydalima perspectalis, family Crambidae) quarantine zone has been expanded to include seven new counties. The new counties include Preble, Clark, Cuyahoga, Ashtabula, Lorain, Lake, and Lucas. The existing BTM quarantine includes Miami, Montgomery, Greene, Butler, Clermont, Hamilton, and Warren counties.

Newly affected nursery stock producers can contact their ODA Nursery Inspector to implement a Compliance Agreement. The Agreement includes a BTM pest management plan developed by the ODA/USDA in conjunction with research scientists.

Compliance Agreements are aimed at reducing the business impacts of a quarantine while at the same time protecting those outside the regulated areas from BTM. As noted in the ODA announcement, Green Industry professionals can contact the Plant Pest Control Section at 614-728-6400 if they have any questions about the new regulation.

The graphic below illustrates the BTM life cycle. It's generally accepted that BTM has three complete generations in southern Ohio; however, this may vary from year to year depending on environmental conditions. It is not yet known if BTM will have three generations in northern Ohio or two generations, as observed in Ontario, Canada, and in the New York counties bordering Lake Ontario.

As shown in the graphic below, BTM has a split-generation between fall and spring. Eggs hatched and small caterpillars started feeding late last season. As day lengths shortened, it caused the caterpillars to enter an overwintering stage called diapause, which is a type of suspended animation.

The small caterpillars are currently housed in protective structures called hibernacula (singular hibernaculum). This makes BTM difficult to detect at this time of the year in lightly infested boxwoods. The ravenous caterpillars will resume feeding on boxwood leaves early this coming spring and can quickly cause damage. Early spring insecticide applications targeting the overwintered caterpillars are critical to reducing early-season damage and helpful in preventing additional damage from successive generations.

Since BTM was first discovered in Ohio in 2023, we have learned that this non-native is only a potential boxwood killer. It can be managed through pruning and properly timed applications of insecticides.

Equally important, research that continues to be conducted by Dr. Theresa Culley (Professor, The Cully Lab, Dept. Biological Sciences, University of Cincinnati) and supported by a Horticulture Research Institute (HRI) grant, has revealed that genetic variability among boxwoods translates into a significant range in susceptibility to BTM. Dr. Cully’s work includes genetically typing boxwoods to inform future boxwood selections for production and planting in Ohio landscapes.

LEARN MORE ABOUT BTM

Learn more about BTM, including effective insecticides that can kill the caterpillars, by downloading printable versions of the OSU Extension three-part fact sheet series on BTM:

1. BTM Range, Spread, and Live Cycle

2. Detecting BTM: What Should You Look For?

3. BTM Management Options

REPORT BTM

In Ohio, you can report a suspected BTM infestation through ODA’s reporting tool:

https://survey123.arcgis.com/share/1b36dd2cf09e4be0a79776a6104ce1dc

In Kentucky, you should contact your county UK Cooperative Extension Office to report a suspected infestation:

https://extension.ca.uky.edu/county

In Indiana, you email reports of suspected BTM infestations to the Indiana Department of Natural Resources:

DEPP@dnr.IN.gov

Ron Wilson