One of the largest and heaviest beetles in eastern North America is the Hercules Beetle, Dynastes tityus. Often individuals reach over three inches long. They are also called Rhinoceros Beetles or Unicorn Beetles because of the two large horns the male sports. (Females have no horns.) These monstrous beetles are harmless to humans and the ferocious horns are used by the males to do battle with each other. The males spar by seeking a grappling hold on their opponent and slamming him into the ground. The purpose is to break the losers head from its body.
Insects in the genus Dynastes are often called Hercules Beetles because, pound for pound, they are the strongest animal in the world, capable of lifting over 850 times their own weight. Some South American species can exceed six inches in length and are often sought as pets. While the adult beetles generally live only three or four months, they are easily raised in captivity and many enthusiasts have a supply of grubs pupating at any one time. The grubs take between ten and sixteen months to mature into an adult beetle.
When gardeners encounter such a massive insect, the first thought is to wonder if their plants are safe from what has to be a massive appetite. They can rest easy, since the grubs only feed on decaying hardwood and the adults prefer rotten fruit and decomposing plant matter. Chances are, they will be happiest in the compost heap. Raccoons and skunks find them particularly tasty, so they might be attracted to the compost heap as well.
Hercules Beetles are nocturnal and are attracted to light. They often flock to streetlights or outside floodlights where they are found flipped on their backs, helplessly waving their legs in the air. While they can fly, they do so awkwardly and without much grace. This leads to mishaps and crash landings.
Deforestation and urbanization has led to a decline of these beautiful beetles. While they are not considered endangered, it is still a good idea to leave a wild spot in your garden for them to live. Don't remove that old stump, plant something in the cavity and let the beetles have the roots. They're harmless and a wonderful addition to the ecology of your garden.