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Ministry of Agriculture, Food and Rural Affairs

Japanese beetle

Japanese beetle Japanese beetle Japanese beetle damage
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Beginner

Scientific Name
Popillia japonica

Identification
Larvae:

  • Milky white,
  • “C”-shaped grubs,
  • 2 cm in length at maturity.

Adults:

  • Beetles 10-13 mm long,
  • Metallic green to greenish-bronze, with coppery red wings and small white tufts on the sides and tip of their abdomen,
  • The head is brown and the body has three pairs of legs.

Damage:

  • Feeding creates a skeletonized appearance on apple foliage,
  • Usually feed in groups, starting at the top of the plant and moving downward.

Often Confused With
N/A

Period of Activity
There is one generation of Japanese beetles per year. The insect overwinters as a larva (grub) in soil. Adults begin emerging in late June to early July, and begin feeding on suitable host plants. Mated females lay 40-60 eggs in the soil during July and August, and the larvae hatch 0-14 days later.

Scouting Notes
Special monitoring for Japanese beetles is not required. Adults are readily observed in orchards during regular orchard monitoring. Where trees are under stress (lack of rainfall, high temperatures and high crop load) and when skeletonization of the leaves has become significant, special insecticides sprays may be necessary.

Japanese beetle traps are available at garden centres. Although the pheromone and floral lures sold with the traps are very effective and attract many beetles each day, research shows the traps attract more beetles than are caught. As a result, susceptible plants in the vicinity of the trap are likely to suffer more damage than if traps are not used. 

Thresholds
There are no thresholds for this pest, however presence of high numbers of beetles on Honeycrisp and other high end cultivars warrant management. 

Advanced

Scientific Name
Popillia japonica

Identification
Adults beetles are 10-13 mm long, metallic green to greenish-bronze, with coppery red wings and small white tufts on the sides and tip of their abdomen. Larvae are milky white, “C”-shaped grubs about 2 cm in length at maturity. The head is brown and the body has three pairs of legs.

Adults feed on the upper surface of apple foliage, chewing the tissue between the veins, creating a skeletonized appearance. Beetles usually feed in groups starting at the top of the plant and moving downward.

Often Confused With
N/A

Biology
There is one generation of Japanese beetles per year. The insect overwinters as a larva (grub) in soil. Adults begin emerging in late June to early July, and begin feeding on suitable host plants. Japanese beetles produce attractive pheromones. Their feeding induces damaged leaf tissue to release volatiles that also attract other beetles to feed and mate. Mated females lay 40-60 eggs in the soil during July and August, and the larvae hatch 0-14 days later. Grubs feed on organic matter and grass roots prior to moving into overwintering sites

Period of Activity
Adults begin emerging in late June to early July, and begin feeding on suitable host plants.

Scouting Notes
Special monitoring for Japanese beetles is not required. Adults are readily observed in orchards during regular orchard monitoring. Japanese beetle traps are available at garden centres. Although the pheromone and floral lures sold with the traps are very effective and attract many beetles each day, research shows the traps attract more beetles than are caught. As a result, susceptible plants in the vicinity of the trap are likely to suffer more damage than if traps are not used. 

Thresholds
There are no thresholds for this pest, however presence of high numbers of beetles on Honeycrisp and other high end cultivars warrant management. 

Management Notes

  • Where trees are under stress (lack of rainfall, high temperatures and high crop load) and when skeletonization of the leaves has become significant, special insecticides sprays may be required.
  • Insecticides applied to control orchard pests such as codling moth generally provide control of Japanese beetles.
  • The tendency of beetles to feed at the top of the tree makes good coverage essential for adequate control.  For information on insecticide to manage this pest, see OMAFRA Publication 360, Guide to Fruit Production - Chapter 3 Apples (PDF) or Apple Calendar only (PDF) :
  •  Migration of these insects into orchards from surrounding areas may make multiple applications necessary.