Japanese Beetle

Japanese Beetles are  a pest that were accidentally introduced to the eastern U.S. in the early 1900’s. Now they are sprouting up everywhere including in Minnesota. This year in the twin cities metro area they are as bad as they’ve ever been and they are devouring everything in their path. Japanese Beetles cause damage in multiple ways.

GRUBS- Grubs are present in your lawn during spring and early summer from eggs that were laid and hatched the previous fall. The grubs devour roots of plants (including: trees, grass, plants, flowers and ornamental shrubs). They cause stress on your lawn by not allowing roots to establish causing large patches of grass to die in the heat of summer. Pull up the dead turf and roll it up until you reach the edge of the green. If it is grubs you will find them here at the edge of the green turf eating away at the roots. Another issue that may arise out of having these grubs in your turf is the fact that other pests eat these grubs. Grubs in your turf will attract moles, shrews, and even skunks that all feed on the larva.

Lawn damage due to grubs

ADULT JAPANESE BEETLE -From about the beginning June through the end of August they mature into the beetle and they emerge hungry. They attack plants of all kinds but they seem to like roses, ornamental shrubs, and fruit trees. The beetle emits a pheromone that attracts other beetles to the spot resulting in an infestation on a single tree or garden.

Beetle Damage

They retreat to the grass in the evening to lay eggs in your lawn/garden. The eggs will hatch in the late summer and the larva will immediately begin the cycle again feeding on roots before winter arrives.

TREATMENT– There are a number of products out on the market that will help control Japanese Beetles. You can attack them in a few different ways. The first is to use a systemic treatment for your trees and shrubs. Infuse by Bonide is a systemic treatment for trees that will help protect them from a number of different insects including Japanese Beetles and Emerald Ash Borer. To kill grubs it’s best to apply a granular insecticide with a spreader from July-September. At this point in the grubs life-cycle they are weak and can be killed off easily.

Grubex Granular grub killer

To kill adult Japanese beetles proves to be a little more difficult. Removing the Japanese Beetles as soon as they are present is key due to the fact that having beetles present attracts more beetles. Use a spray insecticide and thoroughly treat the infested area. You may need more than one treatment to completely kill off an invasion. Be careful to use an approved insecticide when treating  a fruit producing plant and follow the instructions on the bottle.

Bonide Fruit Tree Insecticide

Use of traps to capture Japanese Beetles have mixed results. Some people who use them say that they’ve had great results in controlling the infestation. However, traps use a pheromone that attracts beetles to that spot which may result in attracting more beetles to a spot without actually capturing them.

For more information on Japanese Beetle control and prevention check out the Univeristy of Minnesota Extension page.

For more information on insect control check out these blogs: What to do for Emerald ash Borer, How to get rid of wasps, hornets and yellow jackets, Summer lawn care: how to get rid of moles grubs and ant control, How to get rid of ants in your home and in your yard

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