Watch Out! Japanese Beetles Are Now Active!

Japanese beetle

For those who may not be familiar with Japanese Beetles, they are native to Japan. However, they are surprisingly not a major insect pest in Japan. Japanese Beetles were accidentally introduced into the US around 1916 in the northeast. The climate and plant diversity that greeted the Japanese Beetles was perfect for their development and expansion. By now, Japanese Beetles, both at the grub and adult stages, are one of the worst insect pests in most states east of the Mississippi River.

Japanese Beetle damage

Japanese Beetle grubs, which is in the larva stage of the life cycle, feed on the root systems of all cool-season grasses as well as many other lawn weeds and other plants. The adults feed on the leaves and flowers of over 300 plants. Some of the trees that they prefer to feed on include Lindens, Black Walnut, Norway Maples and Flowering Crab-apples. They also feed on garden beans, grape vines and both the leaves and flowers of roses.

The adult Japanese Beetle is easily identified by the tufts of white hairs on the back end of the abdomen. Their wing covers are copper colored and the body is metallic green. The grub stage looks like a typical white grub with a c-shaped body and reddish-colored head.

Each species of grub can be identified, by the pattern of hairs on their raster (the pattern of hairs and spines in front of the anal slit) or anal slit. Japanese Beetles have two rows of hairs that are arranged in a V pattern on their raster.

Females live for about 30 to 45 days and will lay about 40 to 60 eggs. They prefer moist, loamy soil in well-manicured turf in which to lay her eggs. Eggs hatch in about 2 weeks and the tiny larvae begin feeding on fine root hairs and organic matter. By late summer the grubs will be fully grown and can feed on large sections of turf. Turf can easily be pulled up, like a carpet, to expose the grubs.

Japanese Beetle – Control Damage to Your Lawn and Landscape


More damage is often caused to the lawn by the animals that feed on grubs than by the grubs themselves. Grubs are like mini-sod cutters and will feed on anything in front of them – soil, roots and other organic matter. If the lawn is being watered and fertilized, it is sometimes hard to tell if grubs are active. Skunks, raccoons, opossums and even crows will dig up the turf looking for a tasty treat. This will cause more damage to the lawn than the feeding by the grubs.

beetle damage

If you see the adults feeding on your plants, it is a good idea to take steps to control them. The adults usually feed from the top of the tree and move downward. The adults have the ability to defoliate a tree in a short time. Minor populations can be hand-picked and thrown into a bucket of soapy water.

The adults are more lethargic in the early morning and you may be able to shake them into the soapy water. Large populations may require the use of a commercially available insect control material.

One word of caution, female Japanese Beetle adults can fly upwards to a mile, so even if you control the adults in your landscape, there is still a possibility of facing grub damage in your lawn in September. Applying a preventative grub control treatment to your lawn at this time of year is a good idea – especially if you have adults feeding on your plants.

If you have Japanese Beetle adults that are feeding on your garden plants, shrubs or trees, contact your local Spring-Green office and have your landscape evaluated and receive a price to control these destructive insects.

Japanese Beetle Alert!

In case you have not noticed, Japanese Beetles are in full feeding frenzy. If you see leaves of your plants beginning to look like lace doilies, you probably have Japanese Beetles feeding on them. They are easy to identify – bronze wing covers and a row of little tufts of white hair along their back side. If you see them, you may notice that they are often doing what nature intended them to do, procreate. They are voracious feeders and breeders.

They love to feed on grape leaves, flowering shrubs, roses, rose flowers, lindens and an assortment of other trees and shrubs. The female will look for a suitable place to burrow into a lawn, lay her eggs and move on. The eggs hatch into grubs, which feed on the root system of the grass. One advantage of the dry weather is that the eggs, once laid, only stay viable if the soil is moist, as they draw moisture from the soil. If you are watering your lawn, you may have a problem with grubs later on in the late summer or early fall.

Preventing Japanese Beetles

If you haven’t applied a preventative grub control material to your lawn, now would be a good time. In regards to controlling the adults, just about any commercially-available insect control product will work on them. If the adults are feeding on your vegetable plants, be sure to read the label before purchasing the product to make sure it can be used on vegetables and look for the harvest interval between application and consumption.

You may have also seen hawthorn apples covered with orange colored horns. This is due to a disease called rust . This rust is common on apples, hawthorns and quince. It is often called cedar apple rust, cedar hawthorn rust or cedar quince rust. The reason why is that the disease goes back and forth between a cedar tree, like an arbor vitae, and the other trees. It is an interesting disease to read about and if you do a search on one of the combinations, you will be able to learn more about the disease. Controlling the disease requires a series of lawn disease control applications starting in the spring, so it is too late to do much about it now.