Is something chewing your hibiscus? Has your linden tree been stripped bare?
It seems that central Iowa has received a gift from the eastern states in the form of the Japanese Beetle. This little guy is a voracious eater and can strip a plant bare of leaves in a matter of days. They are very difficult to control because they spend their youth as a grub in the ground and then upon emergence they live in the tops of trees or on your shrubs mating and flying to the ground to lay their eggs. The best method of control is to take a plastic grocery bag out to your garden and tap the adults into it. I usually squash them and throw the entire bag into the trash. I recommend that you do this in the early morning while they are still sluggish. The warmer it gets the more likely they are to fly away upon approach.
You can use chemicals to try to control them; but, because of their living arrangements it can be difficult to get good control. Grub control, applied in July or early August and containing the AI Imidacloprid should help with the grubs. Ortho Home Max Defence containing Bifenthrin as the AI will help with the adults but it will also take out beneficial insects as well so you should use it carefully.
You can spot the adult version of this little guy because of its metallic green head and bronze body but the most distinctive marking is the 6 white “butt” hairs on each side of the body. An adult is about 5/16th of an inch long.
It is not suggested that you put out traps for these things as they will actually attract more of these beetles than you already have.