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Japanese Beetle (Popillia japonica)

As its name implies, Japanese beetles of the scarab beetle family are indigenous to Japan. While not a major pest in its country of origin due to effective biological control, this beetle has migrated and became a huge threat in North America, infesting over 300 plant species.

Japanese Beetle

Physical Description and Identification

Adult 

Size: 1.5 cm

Color: These beetles have a bright appearance due to their color combination – a metallic green head and thorax, and a copper-colored elytra partially covering their abdomen.

Scientific Classification

  • Family: Scarabaeidae
  • Genus: Popillia
  • Scientific name: Popillia japonica

Other Characteristic Features: A row of white tufts of hair can be seen protruding on both sides of their abdomen under their elytra.

Popillia japonica
Japanese Beetles

Larva

The grub is a creamy white with a yellowish-brown head. It appears translucent, and its body has brown setae and short spines all over. A set of dark, strong mandibles is present on the top of its head.
When resting, the larva is C-shaped. Its body consists of 13 segments, 10 on the abdomen, and 3 on their thorax. The segments that make up the thorax each have a pair of legs too.

Japanese Beetle Larvae

Pupa

The pupa ranges from pale cream to metallic green and is 0.7-1.4 cm long. Pupation takes place inside an earthen cell constructed by the larva in its final instar.

Japanese Beetle Pupa

Egg

They range from creamy to off-white and are usually 1.5 mm long. The shapes of these eggs vary from ellipsoid to spherical to even cylindrical at times.

Japanese Beetle Eggs

Quick Facts

Lifespan30-45 days
DistributionNative: Japan Invasive: North America, mainly Canada and the United States
HabitatGardens, fields, forests, and meadows
PredatorsTachinid flies, some birds, raccoons, skunks, etc
Seasons activeLate June through August or September
Diet of adultsLeaves of plants such as birch, canna, crape myrtles, grapes, hops, linden trees, rose bushes, etc
Japanese Beetle Damage

Identifying the Damage Caused by Them

Mature larvae feed on the roots of host plants, causing severe damage over time, while adults skeletonize leaves in groups as well as any fruit that may have grown. Adult beetles generally start feeding on leaves growing on the top of the infected plant, which is a sign of a Japanese beetle infestation.

The beetle’s range appears to be increasing. It has been spotted in large numbers in Wyoming and Washington in the United States, two places where there were no or scarce reported sightings before. Washington had just three of them initially which rose drastically in 2020, with about 20,000 of them thriving in Grandview alone.

Did You Know

  • English entomologist Edward Newman first described this species in 1841.
  • June bugs and Japanese beetles share similarities in their diet and the damage they inflict upon their host plants. However. there are some visible physical and behavioral differences that distinguish one from the other. Both have iridescent green markings, though the June bug has an overall green body. In contrast, the green is combined with copper undertones in the Japanese beetle. Moreover. June bugs are nocturnal, while the Japanese beetle is diurnal.
Japanese Beetle Image
Japanese Beetle Photo
Picture of Japanese Beetle

Image Source: fastactionpestcontrol.com, pbs.twimg.com, extension.umn.edu, ipm.missouri.edu, entnemdept.ufl.edu, media.istockphoto.com, gardendesign.com, gardentech.com

As its name implies, Japanese beetles of the scarab beetle family are indigenous to Japan. While not a major pest in its country of origin due to effective biological control, this beetle has migrated and became a huge threat in North America, infesting over 300 plant species.

Japanese Beetle

Physical Description and Identification

Adult 

Size: 1.5 cm

Color: These beetles have a bright appearance due to their color combination – a metallic green head and thorax, and a copper-colored elytra partially covering their abdomen.

Other Characteristic Features: A row of white tufts of hair can be seen protruding on both sides of their abdomen under their elytra.

Popillia japonica
Japanese Beetles

Larva

The grub is a creamy white with a yellowish-brown head. It appears translucent, and its body has brown setae and short spines all over. A set of dark, strong mandibles is present on the top of its head.
When resting, the larva is C-shaped. Its body consists of 13 segments, 10 on the abdomen, and 3 on their thorax. The segments that make up the thorax each have a pair of legs too.

Japanese Beetle Larvae

Pupa

The pupa ranges from pale cream to metallic green and is 0.7-1.4 cm long. Pupation takes place inside an earthen cell constructed by the larva in its final instar.

Japanese Beetle Pupa

Egg

They range from creamy to off-white and are usually 1.5 mm long. The shapes of these eggs vary from ellipsoid to spherical to even cylindrical at times.

Japanese Beetle Eggs

Quick Facts

Lifespan30-45 days
DistributionNative: Japan Invasive: North America, mainly Canada and the United States
HabitatGardens, fields, forests, and meadows
PredatorsTachinid flies, some birds, raccoons, skunks, etc
Seasons activeLate June through August or September
Diet of adultsLeaves of plants such as birch, canna, crape myrtles, grapes, hops, linden trees, rose bushes, etc
Japanese Beetle Damage

Identifying the Damage Caused by Them

Mature larvae feed on the roots of host plants, causing severe damage over time, while adults skeletonize leaves in groups as well as any fruit that may have grown. Adult beetles generally start feeding on leaves growing on the top of the infected plant, which is a sign of a Japanese beetle infestation.

The beetle’s range appears to be increasing. It has been spotted in large numbers in Wyoming and Washington in the United States, two places where there were no or scarce reported sightings before. Washington had just three of them initially which rose drastically in 2020, with about 20,000 of them thriving in Grandview alone.

Did You Know

  • English entomologist Edward Newman first described this species in 1841.
  • June bugs and Japanese beetles share similarities in their diet and the damage they inflict upon their host plants. However. there are some visible physical and behavioral differences that distinguish one from the other. Both have iridescent green markings, though the June bug has an overall green body. In contrast, the green is combined with copper undertones in the Japanese beetle. Moreover. June bugs are nocturnal, while the Japanese beetle is diurnal.
Japanese Beetle Image
Japanese Beetle Photo
Picture of Japanese Beetle

Image Source: fastactionpestcontrol.com, pbs.twimg.com, extension.umn.edu, ipm.missouri.edu, entnemdept.ufl.edu, media.istockphoto.com, gardendesign.com, gardentech.com

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