Japanese Beetles infest the St. Louis and Illinios Areas

While not native to the United States, the Japanese Beetle has quickly become one of the biggest insect infestations this region has experienced. First found in the US in 1916 at a New Jersey nursery, the Japanese Beetle has spread across the country at a relatively quick pace due to the fact that it does not have many natural predators because of its hard body. The picture shows a group of Japanese Beetles feasting on plant foliage from www.mobot.org.

The Japanese Beetle begins life as a grub and can reek havoc on lawns and plants because they feed on roots in the dirt inches below the surface. In mid June, as temperatures begin to warm, the matured beetle emerges from the dirt, and begins feeding on trees and leaves.

The adult Japanese Beetle has a metallic green head and copper colored wings covering its back with six tufts of white hair on both sides of the beetle’s body. The Japanese Beetle measures 3/8 of an inch in adulthood and can fly about five miles a day when searching for new feeding or breeding grounds.

Known to quickly skeletonize plants and trees, the Japanese beetle will feast on soft leaf tissue, leaving the tougher leaf veins, giving the appearance of a “leaf skeleton” behind. Some of the most susceptible plants and trees are those with soft leaves, including the
● American Chestnut, Elm, Linden, and Mountain Ash trees
● Black Walnut Tree
● Flowering fruit trees such as cherry, plum, peach, apple, and crab apple
● English Elm tree
● Gray Birch tree
● Holly Hock
● Chestnut tree
● Japanese and Norway Maples
● Grape vines
● Roses
● Zinnia

Plants and trees known to be resilient to the Japanese Beetle include the
● American Elderberry and Sweetgum tree
● Black Oak Tree
● Boxelder Tree
● Boxwood Tree
● Butternut Tree
● All varieties of Evergreen trees
● Holly bushes, Magnolias
● Lilac
● Red and Silver Maple trees
● Flowering Dogwood trees



The best defense against the Japanese Beetle is ensuring the dirt and plants purchased from local nurseries do not contain Japanese Beetle larva or grubs. If only a few Japanese Beetles are present they can be hand picked from the plant or tree as well as any damaged leaves. The presence of Japanese Beetles or damaged leaves will only attract more beetles to the area, so if the infestation is relatively small this removal may prevent any more beetles from moving into the affected location.

If the infestation is more severe there are many available insecticides which can be used depending on the level of infestation and life stage the Japanese beetle is in. A different insecticide should be used for adult beetles than is used for grubs which have not reached maturity.

Experts recommend against using a bug bag or pheromone trap. While these methods are effective in catching a great deal of Japanese Beetles, it is believed that they attract beetles from far away in numbers greater than what would not normally infest a property, and can reek havoc while on their journey to reach the bag or pheromone.