Polydrusus (Green Weevils) Beetle AdultView 3 PicturesThis is an iridescent green terrestrial (Terrestrial: Insects which live on land and are fed on by trout only when they incidentally fall into the water are known as "terrestrials" to fly anglers, and they're very important in late summer.) beetle. They're common in northern Wisconsin's forests during the middle of summer, and I found them on the water's surface more than any other terrestrial (Terrestrial: Insects which live on land and are fed on by trout only when they incidentally fall into the water are known as "terrestrials" to fly anglers, and they're very important in late summer.) insect. I saw the trout take a few and caught some trout on an imitation.