Japanese beetles are barraging the state capital. The metallic green and copper insects have been damaging gardens, golf courses and swimming pools in recent years, and many say they are even worse this summer. The beetle originated in an island in northern Japan and first appeared in the United States in New Jersey about 90 years ago. Phil Pellitteri, an insect expert for the University of Wisconsin-Madison, says in the last 10 to 15 years the beetle has arrived in northern Illinois and Wisconsin as well as Iowa and Minnesota. But what used to be an isolated problem in various areas of Wisconsin has become more universal. Adult beetles feed on foliage and fruits of several hundred species of trees, shrubs, vines, flowers and crops from the end of June until early September.