By Staff
Mike Reeves, Morgan County Extension Agent
All we need is a new insect pest to deal with.
Over the last couple of years, the Japanese beetle has been showing up in Morgan County. This insect has been a problem in Limestone and Madison counties for a few years now and has now moved across the river. I expect this new pest to show up in greater numbers each year. To manage the beetle, it will be helpful to know more about it.
The Japanese beetle is a highly destructive plant pest of foreign origin. It was first found in the United States in a nursery in southern New Jersey 80 years ago. In its native Japan, where the beetle's natural enemies keep its populations in check, this insect is not a serious plant pest.
In the United States, however, the beetle entered without its natural enemies and found a favorable climate and an abundant food supply. By 1972, beetle infestations had been reported in 22 states east of the Mississippi River and also in Iowa and Missouri. Since then, the pest has continued to disperse south and west. Isolated infestations have been found in Wisconsin, Oregon and California. Without its natural checks and balances, the Japanese beetle has become a serious plant pest and a threat to American agriculture.
Both as adults and as grubs (the larval stage), Japanese beetles are destructive plant pests. Adults feed on the foliage and fruits of several hundred species of fruit trees, ornamental trees, shrubs, and vines and field and vegetable crops. Adults leave behind skeletonized leaves and large, irregular holes in leaves. The grubs develop in the soil, feeding on the roots of various plants and grasses and often destroying turf in lawns, parks, golf courses, and pastures.
The adult Japanese beetle is a little less than an inch long and has a shiny, metallic-green body and bronze-colored outer wings. The beetle has six small tufts of white hair along the sides and back of its body under the edges of its wings. The males usually are slightly smaller than the females. You are most likely to see the adults in late June and July.
During the feeding period, females intermittently leave plants, burrow about 3 inches into the ground usually into turf – and lay a few eggs. This cycle is repeated until the female lays 40 to 60 eggs.
By midsummer, the eggs hatch, and the young grubs begin to feed. Each grub is about an inch long when fully grown and lies in a curled position. In late autumn, the grubs burrow 4 to 8 inches into the soil and remain inactive all winter. This insect spends about 10 months of the year in the ground in the larval stage.
In early spring, the grubs return to the turf and continue to feed on roots until late spring, when they change into pupae. In about 2 weeks, the pupae become adult beetles and emerge from the ground.
This life cycle takes a year.
The most effective insecticides for control of the Japanese beetle are Bayer Advanced Garden Rose and Flower Insect Killer and Sevin. There is more information available in a publication entitled "Managing the Japanese Beetle: A Homeowners Handbook." This publication gives information about some of the possible biological controls as well as a list of plants that are resistant to or susceptible to Japanese beetle feeding. You can get this publication at our office located at 3120 Highway 36 West in Hartselle or you can access it on the internet at http://www.pueblo.gsa.gov/clc_text/housing/japanese-beetle/jbeetle.html