Insects belonging to the Hemipteran family Reduviidae are collectively known as “Assassin Bugs.” The family includes over 160 species in North America and all are meat eaters. The common name for the family clearly describes how these stealthy hunters make a living.
Family members sport two features important to their predatory behavior: raptorial front legs and piercing-sucking mouthparts. The front legs of assassin bug are designed for grabbing and holding prey. Their mouthparts, called a “beak,” then swing into action to inject paralyzing and pre-digestive enzymes into their prey. They then suck the essence-of-insect from their hapless victims.
Assassin bugs pass through three developmental stages: eggs, nymphs, and adults. This is known as "incomplete metamorphosis." Unlike other incomplete metamorphic insects such as grasshoppers with the nymphs resembling miniature adults, assassin bug nymphs look nothing like the adults.
In fact, the nymphs of our native Wheel Bug (Arilus cristatus) are often mistaken for spiders. Of course, insects have six legs and spiders have eight legs. These are one of the most common assassin bug nymphs currently patrolling trees and shrubs in Ohio. The nymphs have long, spindly spider-like legs and they parade around with their reddish-orange abdomens held upright.
Adult wheel bugs are so-named because of a peculiar morphological feature that rises from the top of the bug's thorax. The structure looks like half of a cogwheel, 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. They will appear on the tree scene later this season in Ohio.
Although caterpillars and sawfly larvae are favored table fare of these voracious predators, they will not turn their beaks up at other arthropod meat morsels. Indeed, they will even nail the probing fingers of uniformed gardeners! 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 bug bite has been described as being equal to or more powerful than a hornet sting, and the wounds may take over a week to heal. It is best to appreciate these beneficial insects from afar.