Japanese Beetle

The Japanese beetle is an invasive species which causes damage to the Colorado ecosystem.

Japanese Beetle. AV Evans/Public Domain

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About This Species

​The Japanese beetle is not native to Colorado. It is a pest to hundreds of plant species in Colorado and is one of the worst pests known to eastern and Midwestern United States. It generally attacks in aggregate, devastating ornamental plants. ​

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Physical Characteristics

Adult Japanese beetles are approximately 3/8 inch in length with a dark metallic green head and metallic, dark tan wings. They also display two white rear tufts and five white lateral tufts of hair. 

​Japanese beetle larvae or grubs are “C” shaped. They also have a pattern of hairs on their brown hind ends that form a small “V” shape, visible under a 10-power hand lens. 

Habitat

Most beetle larvae pass the winter 2-6 inches below the soil surface, although some may go as deep as 8-10 inches. They live in the soil and feed on grass roots, among other plant species.

Diet

​In early July adults can be observed feeding on vines, linden trees, roses, and many other ornamental plants. Japanese beetles have been known to feed on the following plants, among many others: American chestnut, American elm, American linden, American mountain ash, apple, birch, black cherry, cherry, flowering crabapple, grapes, hollyhock, horse chestnut, Norway maple, plum, roses, and walnut. 

Reproduction

As a grub, this beetle remains in the soil for 10 months, emerging as an adult in June. 

Insect
Popillia japonica