Wheel bug (Arilus cristatus) nymphs are completing their development and the adults of these large, unusual looking bugs are beginning to lurk among the leaves of trees and shrubs in Ohio in search of prey. Although caterpillars and sawfly larvae are favored table fare of this impressively large predator, they will not turn their beaks up at other arthropod meat morsels.
These large bugs belong to the Hemipteran family Reduviidae which is represented in North America by over 160 different species. Members of this family are collectively known as assassin bugs; a name that clearly describes how these stealthy hunters make a living.
Wheel bugs get their descriptive common name from a peculiar morphological feature that rises from the top of the bug's thorax. The structure looks like half of a cog-wheel, with the gear teeth clearly visible. Wheel bugs are big, measuring over 1 1/4" long, and their color varies from light gray to bluish-gray to grayish-brown.
As with all predatory bugs, wheel bugs are equipped with piercing-sucking mouthparts that are used to inject paralyzing and pre-digestive enzymes into their prey. They then suck the essence-of-insect from their hapless victims. While these are beneficial insects, they should not be handled. All members of the family are capable of delivering a painful bite to people. The pain of a wheel bug bite has been described by those who have suffered the wheel of misfortune as being equal to or more powerful than a hornet sting, and the wound may take over a week to heal.
A Case of Mistaken Identity
In 2015, a panic was touched off in several Mid-Atlantic and Mid-Western States including Ohio by possible cases of mistaken identity between wheel bugs and kissing bugs (Triatoma spp.). A Cincinnati news headline captured the confusion, "'Kissing bug' brings deadly parasite to Tri-State." The parasite is the protozoan Trypanosoma cruzi that causes the potentially deadly Chagas disease. Of course, the protozoan had not found its way to the Tri-State area in Ohio, or any area in the U.S. outside of where it had been previously documented.
Entomologists at Virginia Tech viewed all of the purported kissing bug images sent to a local news media outlet during the panic. In every case, the true bug was the wheel bug. Wheel bugs and triatomine bugs are about the same size and both belong to the Reduviidae family so they share some family traits. However, kissing bugs lack the wheel bug's distinctive half-cog-like structure.
On the other hand, I have found and photographed the Bloodsucking Conenose (Triatoma sanguisuga), which is a type of kissing bug, in the Greater Cincinnati area. According to a paper published in the Ohio Journal of Science in 1960 titled, "Arthropods of Medical Importance in Ohio," the bloodsucking conenose is found in southern Ohio. Although rare, they appear to be endemic to the region.
However, the Centers for Disease Control and Prevention does not list Ohio among the geographical areas where Chagas disease has been confirmed. The highest concentration of the disease is in central and South America with some cases reported in southern Texas.