Japanese beetle
The Japanese beetle, scientifically known as Popillia japonica, is a beetle species originally from Japan but now commonly found across the eastern United States, from Maine to South Carolina. Introduced to the U.S. in 1916 via imported iris roots, this insect thrives in woodland areas and meadows, where it primarily feeds on the foliage and fruits of various plants, including rose bushes, grapes, and birch trees. The beetle is recognizable by its shiny, iridescent body, which can exhibit colors such as black, green, bronze, and gold, and is typically less than one inch long.
Mating occurs in late July to early August, with females laying 40 to 60 eggs in the soil. The larvae, known as grubs, develop through several molting stages before emerging as adults. Japanese beetles are considered pests in agricultural environments due to their feeding habits, prompting efforts to control their populations through natural predators like tachinid flies and tiphid wasps. Adults have a lifespan of about 30 to 45 days and, despite their pest status, are not threatened as a species.
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Japanese beetle
In spite of its name, the Japanese beetle does not only live in Japan. In fact, it is found in the United States from Maine to South Carolina. The Japanese beetle was first introduced into the United States in 1916 when it was accidently imported on iris roots from Japan.
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Coleoptera
Family: Scarabaeidae
Genus: Popillia
Species: Japonica
Although the Japanese beetle was originally only found in Japan, this insect made its way to the United States in 1916. It was accidently imported on iris roots from Japan. Typically, the Japanese beetle is found in woodland areas and meadows from Maine to South Carolina in the United States and in similar habits throughout Japan.
The Japanese beetle feeds mostly on the fruits and leaves of its habitat. It enjoys rose bushes, grapes, hops, and birch trees. Like other beetles, it chews its food with its strong, biting mouthparts. The Japanese beetle's mouth consists of its strong jaws, or mandibles, which it uses to cut and chew, and its maxillae and lips, which are used to help taste and to help push food into the Japanese beetle's throat.
This less than one inch (15 millimeter) long beetle has a shiny, oval or rounded body which may appear black, purple, blue, green, bronze, or gold. Regardless of the color, the Japanese beetle is iridescent, or shining with all of the colors of the rainbow like an oily puddle. Typically, the Japanese beetle has gray hair on its underside and white hair on its abdomen.
On the head of the Japanese beetle are a pair of antennae and a pair of eyes. The beetle uses these features to help it sense its surroundings.
Like other beetles, the Japanese beetle's front pair of wings is formed into two hard cases, or elytra. The elytra protect the Japanese beetle's delicate rear wings from exposure to the environment. When the Japanese beetle is crawling, the elytra are tucked down smoothly along the beetle's back, but when the beetle flies, the elytra lift, and the rear wings carry the beetle into the air.
Like other beetles, the Japanese beetle is divided into three main body parts. Each beetle has a head, thorax, or middle section, and abdomen, or lower-body section. The beetle's six legs extend from its thorax.
Mating season for the Japanese beetle takes place during late July to early August. After mating, the female Japanese beetle lays her 40 to 60 eggs in the soil and around plant leaves.
Young Japanese beetles hatch from their eggs as tiny beetle larvae. These grubs, or larval beetles, appear as short, chubby, worm-like animals. As they grow and develop, they molt, or shed, their skins many times. Eventually, they molt their larval skins completely and move into their pupal stage. The beetles continue to grow during their pupal stages and eventually molt again and emerge as adult beetles.
Because of the diet of the Japanese beetle, it has become a pest in agricultural societies. Humans have tried to rid their plants of these pests by introducing natural predators, such as parasitic tachniid flies and tiphid wasps.
The average life span of the adult Japanese beetle is between 30 and 45 days. They are not a threatened species.
Bibliography
“CDFA - Plant Health - Japanese Beetle Pest Profile.” California Department of Food and Agriculture, 2024, www.cdfa.ca.gov/plant/pdep/target‗pest‗disease‗profiles/japanese‗beetle‗profile.html. Accessed 11 Apr. 2024.
“Japanese Beetle.” Wisconsin Horticulture, 4 Dec. 2020, hort.extension.wisc.edu/articles/japanese-beetle. Accessed 11 Apr. 2024.