Lawn and Garden Insect Pests: Japanese Beetles
Popillia Japonica Newman
If you have Japanese Beetles in your area, you most certainly know it. An
infestation of these bugs, is quite visible. Japanese beetles aren't shy.
They are readily seen on plants. They can damage the flowers and foliage
of plants in a hurry.
The USDA describes Japanese Beetles as a "highly destructive plant
pest". As a matter of fact, they are the most serious of all lawn pests.
Adult Japanese Beetles attack the foliage, flowers, or fruit of several hundred
species of plants. This includes, flowers, vegetables, bushes, trees and
Japanese Beetle larva, or "grubs", feed on the roots of the grass in your
lawn, spending the winter months under your lawn. A large infestation can
damage the lawn.
Japanese Beetles came from Japan. They were first discovered in 1916 in Riverton,
NJ. Without a natural predator in North America, they spread quickly. They
are now found in most states east of the Mississippi River. Infestations
have also been found west of the Mississippi.
Identifying Japanese Beetles:
Adult Japanese Beetles are a little smaller than 1/2" long. they have metallic
green bodies and bronze wings. The female grows a little larger than
the male. They are easy to spot on the leaves of your plants, or in the flowers.
As grubs, they grow to almost an inch, and are whitish color. Turn over some
sod, and you will find them at the root line.
Japanese Beetle Life Cycle:
Adult Beetles emerge from the ground in late spring to early summer. They
spend their time devouring plants. The female burrow underground numerous
times to lay eggs. She will lay them about 3 inches below the surface,
a few eggs at a time. Over a few weeks, each female will deposit about 40
60 eggs in your lawn.
In mid summer, the eggs hatch, and the grubs begin to feed on the roots of
your lawn. At this point, they are only a couple inches below the surface
of the lawn, and can be treated with lawn grub killers. In late fall, they
burrow down 4-8 inches to overwinter.
In the spring, the grubs return to the roots of grasses to feed. By late
spring, they change into pupae. This stage lass about 2 weeks, before emerging
as adult, flying beetles.
Controlling Japanese Beetles:
The picture above, is a Hollyhock plant with severe beetle damage.
For adult beetles:
Most chemical sprays, that are available to homeowners, are not strong enough
to kill them. Check the label on the insecticides at your local garden store,
to see if they are effective against Japanese Beetles.
Japanese Beetle traps can help reduce their numbers. These traps contain
a sex hormone to attract them into the trap.
You can also pick them off plants. After picking them, make sure to kill
them. Don't just dispose of them in the trash, to later escape.
Controlling Japanese Beetle Grubs.:
USDA - Japanese Beetle