The Hercules beetle can grow to be up to 8 inches in length. For a long time people thought that the two sexes were completly different species, because they looked nothing alike. Males have horns and a greenish shell covering females have no horns, with a red covering. The males horns can be 2.5 to 4 inches long.
Photo Courtesy of: Mike Plagens http://arizonensis.org/sonoran/fieldguide/arthropoda/dynastes.html