Japanese beetles are this generation’s destroyer of the landscape. These little metallic militants appear in swarms in July and last for months. They are feeding on their favorite plants and when those are decimated, they move on to the next.  They love roses, fruit trees, vegetables and especially linden trees. Reducing the Japanese beetle population requires a different strategy than the traditional preventative control for white grubs.  Protecting our favorite roses and fruit trees will involve treatments for adult beetles as well as the grub stage. 

What is the Best Way to Control Japanese Beetles?

Traditional preventative grub control had been easy.  Before the Japanese beetle invasion, we never worried about the adult stage masked chafer. They don’t feed on plants the same as a Japanese beetle or reproduce in multiple hatchings. Effective Japanese beetle control will now require multiple phases:

Best Preventative for Trees and Shrubs

Preventative treatment for adult beetles on shrubs and trees begins in early May with a soil drench application of Dominion Tree & Shrub Insecticide. A direct soil application of Dominion Tree & Shrub around trees and shrubs should be applied before Mother’s Day to provide systemic control with up to twelve-month residual. The insecticide is absorbed into the plant, killing any insect that eats the leaves or bark. 

Best Curative for Trees and Shrubs

Swarms of adult Japanese beetles are more of a challenge to control.  The best method is to spray them with Cyonara, Bifenthrin or Malathion. These products are compatible with most fruit and vegetable crops as well as landscape plants. If you discover just a few beetles, they can easily be picked off and dropped into a bucket of soapy water. 

Best Preventative for Lawns

As the Japanese Beetles move through their life cycle they will start to lay eggs in the grass. To prevent grub damage, start treating the yard with Long Lasting Grub Control in early summer before the lawn goes into heat stress. This is a preventative treatment, and is designed to be applied before a potential grub problem develops. It is normally applied in late June to early July and kills the baby grubs as they hatch. Long Lasting Grub Control will stay active in the lawn for about ninety days. 

Best Curative for Lawns

The Hail Mary is applying Quick Kill Grub Control in the middle of September as Long Lasting Grub Control has faded. Quick Kill is the only effective contact-kill for white grubs. It is very fast acting with a short active life. It’s important to water heavily after application to help penetrate any thatch in the yard. If the problem recurs, you can apply a second or third dose of Quick Kill Grub Control.

Why Are Japanese Beetles So Bad?

Japanese beetles reproduce at very high rates, unlike their cousin the masked chafer (the “June bug”) that lives only a few weeks. The adult Japanese beetle lives for months to eat, mate, and lay eggs recurrently. Once the eggs start to hatch into grubs, continuous waves of ravenous white grubs begin feeding on the roots of your grass.

Why do Japanese Beetles Swarm?

Plant odors attract both sexes to potential food sites. Japanese beetle feeding produces odors which act as pheromones to attract other Japanese beetles to the area to feed and mate. Pheromones are chemical odors used by insects to communicate. 

Where Did Japanese Beetles Come From?

Originally from Asia, Japanese beetles were brought over to the United States in 1917 into New Jersey. Currently the insect can be found in all states east of the Mississippi River, except Florida and Louisiana.

Japanese Beetle Life Cycle

What About Japanese Beetle Traps?

Japanese beetle traps do work in that they capture adult beetles. However, placement is critical. DO NOT place the traps near any plant material you do NOT want the beetles feeding on. Although the trap is quite effective in attracting the beetle, only about 70 percent of the beetles end up in the trap. In addition, pheromone traps attract more beetles to your property than would have visited your property naturally. Research has shown that putting the traps in the perimeter of the property well away from valuable plantings or vulnerable crops may be the best use of the traps. Traps work better if you also get your neighbors to set out traps. Use a community-wide approach of 25 to 50 traps per square mile.

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