Wheel Bug: An Assassin in Your Bug Collection
Arilus Cristatus as a Specimen, Predator and Pet
Though it begins life as a brightly colored nymph (red and black), the wheel bug takes on a dusty brown appearance in adulthood and molts until reaching 1 to 1.5 inches in length, making it one of the largest of the true bugs in North America. At maturity, it can fly, and moves with robotic precision, slowly lying in wait on trees and flowers to prey upon other insects - particularly honey bees and caterpillars (Drees and Jackman, 1999).
There is one generation of Arilus cristatus per year, with winter spent as eggs massed together in groups of 40-180, resembling a honeycomb (Mead, 2005). The eggs hatch in late spring and nymphs begin the hunt for food immediately (Day, 1996).
Born to kill
The wheel bug is born a predator – soon after hatching, nymphs can be seen viciously attacking aphids and caterpillars, even eating one another if necessary. Cannibalism has been reported in adults, with females consuming males after copulation, though this is not the normal ritual as noted with the black widow spider (Mead, 2005).
Known also as the ‘assassin bug’ for its membership in that infamous category of predators, the wheel bug is equipped with an arched, straw-like tool or beak that projects from its head, used to strike down and paralyze prey, injecting an enzyme that breaks down the bodily fluids of its victim for consumption.
The wheel bug earned its moniker by perhaps the most distinctive feature of its body – the half cog or wheel shape, similar to a circular saw blade - that protrudes from its back. Less obvious characteristics include its ability to make a chirping noise by friction created with the rostrum, and the defensive measure of exuding an unpleasant odor from scent glands when provoked (Mead, 2005).
Like most garden predators, the assassin is considered a beneficial insect – controlling populations of many unwanted pests. They do not usually appear in large numbers, so control is not typically advised. They are especially beneficial to trees infested with caterpillars that can defoliate a grove quickly.
A killer collection
Wheel bugs have been known to bite humans if cornered, so while collecting it as a specimen, take care not to handle it directly. Instead, coerce the bug into a jar using a leaf or other object. The sting is reportedly many times more painful than a hornet and may take an extended period of time to heal (up to six months) due to the paralytic enzyme that is emitted from its beak (Mead, 2005).
Pin the assassin the same day it is collected, or else place it in a relaxing jar to prevent breakage. To make a relaxing jar, place sand or another absorbent material into a jar you can seal, dampen it and add a couple of drops of disinfectant, bleach, phenyl or ethyl acetate to prevent mold or parasite infestation (Keith and Heng-Moss, 2003). After a day or two in the relaxing jar, the wheel bug can be labeled and pinned for your collection.
An exotic pet
One alternative suggested by the University of Kentucky is to keep the wheel bug as a pet in a terrarium, though this requires daily feedings of caterpillars or earthworms and great care to avoid direct contact with the bug. In warmer climates, the best a wheel bug can hope for is to live until the frost, but the pet assassin may live through Christmas!
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