It looks like something from the movie Jurassic Park and gardeners often wonder if it is real. Arilus cristatatus, commonly known as the Wheel Bug is a voracious garden predator and is classified as a beneficial insect. It gets its common name from the prehistoric looking wheel shaped armor on its back. The function of this wheel is not known, but it may alert insect eating animals and birds that it tastes as bad as it looks.
It is one of the largest true bugs in North America, with the bodies reaching as long as 1 1/2" or 38mm and belongs to the family Reduviidae, which includes a number of assassin bugs. Assassin bugs are noted for their predatory habits, as they stalk their prey and quickly pounce upon the hapless victim. They inject a powerful poison from their ‘fang' called a rostrum and the substance liquefies the internal organs of the unlucky captive. The wheel bug then sips the resulting goo from the shell of its prey. This sounds like the plot of a horror movie, but sometimes nature is more frightening than fiction. Gardeners are cautioned not to handle or disturb this insect, as its bite is painful and often described as worse than a hornet sting, sometimes resulting in a scar.
Before you decide to systematically execute any wheel bugs you may find in your garden, note that their favorite foods are Japanese beetles, aphids and tent caterpillars. They aren't aggressive and move slowly, so as long as you let them go about their business, they'll leave you alone. They can fly, but it is a clumsy process, so they prefer to walk and will even climb trees to search for prey. When they fly, their wings make a similar noise to a grasshopper flying.
Arilus cristatatus is found in North America from Rhode Island to Texas, but there are 4 recognized species of Arilus world-wide with similar habits. Tropical cousins in the subfamily Triatominae, known as kissing bugs, prefer the blood of vertebrates. This not-so nice member of the family carry parasites that cause Chagas disease, a tropical illness. The North American wheel bug is shy and so well-camouflaged that many people have never seen one. They do not exist in great numbers and chances are you'll never see more than one or two in a season. If one appears in your garden, simply let it proceed about is business of eliminating the pest insects. Consider it free, organic pesticide.Find this bug and others in our BugFiles database.