What is a Japanese Beetle?

The Japanese beetle, or Popillia Japonica, is a member of the beetle family that has risen to prominence as a pest in the United States. Though the Japanese beetle has many predators to keep their numbers in check in it's native Japan, there are no natural predators in America. This lack of natural predators has given the Japanese Beetle the ability to cause over $450 million US Dollars (USD) in damage.

The adult Japanese beetle is, on average, approximately 1/2 inch (11 mm) long, and a little under 1/4 inch (6 mm) wide. The body of the beetle is a deep metallic green color, while the wings are the color of polished copper. There are six patches of white hairs on each side of the abdomen on the Japanese beetle. The larvae are white, with long brown hairs and short spines. The life cycle of a Japanese beetle is between one and two years.

Japanese beetles, sometimes referred to as jitterbugs, feed off of a wide variety of plant life, including up to some 300 types of plants. Adult beetles will feed from a variety of flowers, vegetable plants, and other assorted foliage. In the larva stage, Japanese beetles feed from a large variety of roots and grasses. The combined feeding habits of the Japanese beetle, from larva to adult, gives it the ability to wreak havoc in its habitat.

Common host plants for the adult Japanese beetle include but are not limited to, the leaves of plants bearing asparagus, some types of beans, citrus fruits, plums, raspberries, corn, and maple trees. Other host plants include turf grass, walnut trees, and sassafras. The Japanese beetle usually primarily damages the leaves of the aforementioned plants, and after feeding will leave just a framework of the leaf. Larvae will feed on the roots of grasses and other plants, damaging the plants ability to absorb nutrients and water. A common indicator of Japanese beetle larva is dead patches of grass or other foliage.

As with most invasive species, there are several methods for removing Japanese beetle infestations. The specific application of these methods may have varying degrees of success. For a localized infestation, the beetles can be physically removed from the plant. Traps can be placed that lure in and kill beetles, however if used improperly they can be more destructive than useful. Since most commercially available Japanese beetle traps lure beetles, they can also result in a larger degree of infestation.

Pesticides are available that are highly toxic to the Japanese beetle. These pesticides produce varied results. Since the pest is very resilient to both poisons and physical damage, many previously successful pesticides have been deemed unusable in recent years.