Text Size:   A+ A- A   •   Text Only
Site Image
Japanese Beetle: A Pest of Turf & Roses
Japanese beetle
JB adult
The Japanese beetle (Popillia japonica) is a highly destructive pest that was first found in the United States in 1916. It is native to Japan, where the beetle´s natural enemies keep the population under control such that it is not a serious plant pest. Due to favorable conditions, beetle infestations have been reported in 22 of the states east of the Mississippi as well as Iowa and Missouri. Isolated infestations have also been reported in Oregon, California, Nebraska, and Wisconsin.
In both larval and adult life stages, the beetle can cause extensive damage and expense in agricultural and horticultural industries by damaging nurseries, seedbeds, orchards, and field and truck crops. Sites with large areas of turf such as parks, golfcourses, cemeteries and businesses are also at risk.
It can also be a problem for homeowners in lawns, gardens, fruit trees and ornamental trees and shrubs. Western Oregon has extensive areas and plantings which would be suitable for Japanese beetle survival and reproduction.

JB hosts
Adults feed on several hundred species of woody and herbaceous plants. Some of the more preferred hosts include roses-especially yellow and light colored varieties, grapes, most deciduous fruit trees, shade trees, most shrubs, garden-corn, soybean, asparagus, blueberry, rhubarb, sassafras, and evening primrose, hollyhock, and many weeds. The adults typically skeletonize leaves and leave behind large irregular holes, consume flowers, and devour fruit. The grubs develop in the soil feeding primarily on the roots of turf in lawns, parks, golf courses, and pastures, but will also feed on the roots of crops such as corn, beans, tomatoes, and strawberries.

JB life cycle
The life cycle of the Japanese beetle takes one year. In mid-June to early July, adults emerge from the ground to feed on the foliage around them until mid summer with peak abundance usually during July and August.

JB larva (grub)
JB grub
JB larva (grub)
The eggs hatch in about two weeks and the young grubs begin to feed until late autumn when the grubs burrow 4 to 8 inches into the soil and then spend the winter inactive. When spring comes and the temperature warms, the grubs become active and feed on roots until fully grown. The larvae look like many other grubs found in the soil. Their bodies are C-shaped and creamy white with the posterior end darker. Full grown grubs are about 1 and 1/8 inches long. When fully grown the grub forms a pupa and after two weeks, the pupa becomes an adult beetle and emerges from the ground. Japanese beetles spend about 10 months of its life in the ground in its larval stage.

JB adult
JB adult
JB adult
The Japanese beetle adult is bright metallic green with copper-colored wing covers and is about 3/8 of an inch long and 1/4 inch wide. Two small tufts of white hair occur just behind the wing covers with five patches of white hair along each side. The adults are active flyers able to fly short distances between food sources. They are easily transported long distances on plant material or in planes, trains, or automobiles away from infested areas. The adults mate and the females lay eggs intermittently during the feeding period until 40 to 60 eggs are laid- usually in turf.

JB in Oregon
JB trap placed near roses
A JB trap placed near roses beside a house.
Like the Gypsy moth , the Japanese beetle can hitchhike across the country.They are easily transported long distances as hitchhikers on shipments of plant material or accidentally carried in planes, trains, or automobiles away from the infested area. Fortunately, to date, we have no established populations of this beetle. Through the efforts of our seasonal survey technicians we have been able to detect isolated infestations early which allows us to eradicate this potentially threatening pest. Annually, we use a type of insect trap to detect the presence of this beetle throughout the state of Oregon during the months of May-September. We also work cooperatively with USDA APHIS PPQ and have an inspection team who inspects cargo airplanes that land at PDX from quarantined states. If you are interested in more information regarding the history of the Japanese beetle in Oregon please visit our Annual Report web page.

How you can help?
Steps you can do to help stop the Japanese beetle:
  1. Report suspectedJapanese beetle life stages to Oregon Department of Agriculture.
  2. Report any extensive damage to lawns, roses, grapes, fruit or other trees and shrubs to the Oregon Department of Agriculture.
  3. Cooperate with Oregon Department of Agriculture seasonal survey staff when they request permission to place traps on your property during the summer.
  4. Observe quarantine regulations by not moving plant material, outdoor household articles out of Japanese beetle infested areas without certification.

Additional information
ODA Japanese beetle survey

annual report