When Treating for Japanese Beetles Isn’t a Good Idea

Those pesky Japanese beetles have broad appetites!  They feed on roses, trees, perennials, vines and even our vegetable plants.  Knocking them into a pail of soapy water is certainly a satisfying (read vengeful) way to keep their numbers down.  But when their numbers are overwhelming, it’s tempting to look for an insecticide to stop the damage.

If using insecticides to manage Japanese beetles, be aware that many insecticides will kill pollinators too.  Considering 1/3 of our food supply exists because pollinators pollinate, concern for their health is vital to our health.

To illustrate this point, here’s a great example of the need for caution. This rose has a bumble bee, sweat bee and a barely discernible Japanese beetle all feeding on the same flower. Applying an insecticide to the flower would kill the Japanese beetle—and the bees.

Be aware that the flowers on many plants are magnets for our pollinator friends.  To keep pollinators healthy, learn to tolerate cosmetic damage caused by the Japanese beetle, knowing their activity will slow towards the end of July.  Where possible, apply insecticides only to the foliage and not the flowers of favored plants. You can remove flowers and flower buds before applying an insecticide, and/or wait until flowers are finished blooming.

bee and japanese beetle on rose

Kathleen Cue
Horticulture Program Coordinator at Nebraska Extension
Kathleen serves as a Horticulture Program Coordinator. She educates people on making smart plant choices to reduce use of fertilizers and pesticides in their landscape which has a positive impact on air, water, soil and environmental quality, property values and people’s pocketbooks. She provides leadership and coordination of the NE Extension in Douglas-Sarpy Counties Master Gardener volunteer programs: the Master Gardener Speakers Bureau, and "Ask the Master Gardener" Consultations.

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