They are very beneficial in the landscape as they prey on a wide variety of insects. Unfortunately, they also prey on lady beetles and honey bees. They have only one generation per year.
They pack a mean wallop, so be careful when working in the landscape. When disturbed, the wheel bug can inflict a painful bite. The bite has been described variously as worse than stings from bees, wasps, or hornets. Barber (1919) and Hall (1924) described in detail the effects of such bites.
In general, initial pain often is followed by numbness for several days. The afflicted area often becomes reddened and hot to the touch, but later may become white and hardened at the puncture area. Occasionally, a hard core may slough off, leaving a small hole at the puncture site.
Healing time varies but usually takes two weeks and may take half a year. Smith et al. (1958) reviewed the literature concerning wheel bug bites and concluded that serious or prolonged effects from these bites usually are due to secondary infection or an individual hypersensitivity.
For more information about the wheel bug (click on the blue link).