Japanese Beetle Bug

The Japanese beetle

Japanese BeetleThe Japanese beetle, also called Popillia japonicais, is one of the most devastating pests in North America. As its name indicates, the Japanese beetle is indigenous to Japan. This metallic green beetle with copper shaded wings  is about a half inch in length. Although it was first detected in New Jersey in 1916, it now has expanded the geographical range into several states including Ontario, Minnesota, Iowa, Missouri, Arkansas, Georgia and Alabama. Apart from the USA, this beetle has been detected in Canada, Italy and in the islands of the Azores.

The adult beetles are known to have large range of hosts around 400 species including Corn, Roses, Beans, Peaches, Strawberries, Tomatoes, Peppers, Grapes, Plums, Pears, Raspberries, Blackberries, Linden trees, Blueberries, Zinnias and many others. Their larvae, or white grubs, are also harm various types of plant roots including ornamental trees and shrubs, turf grasses and garden crops.  The adult beetles eat the foliage tissue between the leaf veins, leaving the veins behind. Affected leaves get withered and die-off. The adults are known to attack flower buds and fruits too. The larvae destructs small seedlings but most commonly damages the turf. When the turf is attacked by grubs, first the color fades and then it begins to feel spongy under foot and can be easily pulled back to see the grubs. Grubs feed in colonies and kills the turf in uneven patches.

From a pest-management standpoint, it is important to recognize the weaknesses of this destructive beetle.  The larval stage of the Japanese beetle lives in turfs, where it eats the roots. This larva is vulnerable to a fatal disease called milky spore disease, which is caused by a bacterium. Taking this as an advantage, the USDA has developed a Japanese Beetlebiological control using this milky spore bacterium.  It is commercially available as a powder to apply on lawns and grasslands. It takes from one to five years to ensure maximum protection against the larvae under standard application in low-density.

Plants that are highly prone to damage include Roses, Mallow, Morning glory, Grapevines and other close relatives.  When the beetles are assembled, removing them by hand may provide adequate protection. The initial presence of the pest will attract more beetles. So removing them at their first stage is important. Several Japanese beetle traps are commercially available to capture these clumsy fliers. Mixtures of sex pheromones are used in these traps as baits to attract the adult beetles. These beetle traps can capture thousands of beetles in a day from highly infested landscapes. There are some home remedies worth trying, although they may not be as effective. Application of a natural Japanese beetle repellent such as Chives, Garlic, Tansy or using a homemade insecticidal soap to avoid the pest aide in control.