June 18, 2014

What are Japanese Beetles?

Japanese BeetleJapanese beetles are small pests that carry a big threat. They do not discriminate on what types of plants to feed on, in fact, they are classified as a pest to hundreds of different species. They are one of the most major insect pests in the Eastern and Midwestern US, causing monumental damage to crops each year. Native to Japan, they were first documented in the US in 1919, and have since spread across the country.

How to Identify Japanese Beetles

Japanese Beetles are ½ inch in length and metallic blue-green with tan wings, with small white hairs lining each side of the abdomen. They lay eggs in the soil during June, which develop into tiny white grubs. These grubs will remain under wraps for about 10 months and overwinter and grow in the soil. They emerge from the soil as adult beetles and begin feeding in June. They usually attack plants in groups, which is why damage is so severe. Although the lifecycle of the adult Japanese beetle is barely 40 days, it can cover a lot of ground. Look for leaves that are “skeletonized” (only have veins remaining). This is a tell-tale sign of Japanese Beetles.

How to get rid of Japanese Beetles

  • Try to select plants that Japanese Beetles will not be attracted to.
  • In the grub stage of late spring and fall (beetles have two life cycles per season), spray the lawn with 2 tablespoons of liquid dish-washing soap diluted in 1 gallon of water per 1,000 square feet. The grubs will surface and the birds will love you. Spray once each week until no more grubs surface.
  • Unfortunately, the most effective way of getting rid of Japanese beetles is to hand pick them. It’s time consuming, but it works, especially if you are diligent.
  • You can also purchase parasitic nematodes (most garden centers have them) and drench the soil around the area where you have the problem.
  • Neem oil and sprays containing potassium bicarbonate are somewhat effective.
  • Put down a dropcloth and, in the early morning when they’re most active, shake them off and dump them into a bucket of soapy water. They will not survive.