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How to deal with the Japanese beetle

Japanese beetles have been recently spotted in southern Ontario. 

As Dr. Sarah Jandricic of OMAFRA reports in the ONFloriculture blog last week, the Japanese beetle isn’t just a nursery or turf pest. In fact, it can also invade greenhouse-grown ornamentals if left outdoors when adult beetles are in flight or if in contact with contaminated plants. It’s especially important if growers are looking to ship beyond Ontario borders or to satisfy Japanese beetle certification program requirements.

So what should you spray and when? Three active ingredients are currently registered: chlorantraniliprole (specifically Acelepryn), chlorpyrifos and imidacloprid.

Product recommendations will differ based on application timing. Some pesticides have the greatest effect on smaller larval stages. Another important consideration is the residual activity of the insecticide – a shorter residual period could be ideal for curative purposes, while a longer duration could be used for preventative purposes.

Since soil-applied pesticides currently registered for use are not effective against egg and pupal stages, a longer-period residual product could be applied preventatively to help target larvae as they hatch.

Visit the ONFloriculture blog post for specific application timing and product recommendation, along with a helpful decision tree to help you figure out if you need to spray.