Meet Your New Neighbors! Wheel Bugs!
By Judy Ferris, Master Naturalist & Guest Blogger
Recently, you may have seen tiny black insects – slender-legged, with brilliant red butts which point skyward, and yellow tips on their black antennae. Congratulations on spotting a Wheel Bug nymph!
Adult Wheel Bugs mate in autumn; the time of year when you are most likely to see them in their adult form. After mating, females lay up to 200 eggs on trees, bushes, porch railings, and other objects. In spring, usually in early May, Wheel Bug babies erupt, enmasse, from their egg cases. The results can be quite startling!
The tiny nymphs are downright cute. Already, however, they are armed with that signature fierce, hollow beak known as a rostrum. The rostrum is the Wheel Bug‘s primary weapon as well as its only means of sucking up food. Luckily, unless a meal or danger is in the offing, the rostrum is kept tightly tucked beneath the bug‘s chin. If disturbed, however, even small nymphs can unleash their rostrum to deliver a painful bite.
Wheel Bug nymphs generally hatch in early May. They have a topsy-turvy life before they become awe-inspiring adults. The youngsters must undergo 5 molts or instars, shedding their exoskeleton each time. This gradual metamorphosis toward adulthood sounds worse than puberty! The average length of each molt is roughly 19 days. Thus, it takes about 94 days for the nymphs reach maturity. (Hagerty & McPherson 2000) The final molt generally occurs in July. All too soon, our cute little nymphs say good bye to their idyllic childhood and transform into intimidating adults.
Wheel Bugs ( Arilus cristatus ) are large members of the Assassin Bug (Reduviidae) family. It‘s quite possible that when Wheel Bugs were created, Mother Nature delegated the task to a committee. That‘s the only way to explain the Wheel Bug‘s hodge-podge assemblage of mis-matched insect parts! Unfortunately, the committee itself may have fallen prey to yet another reorganization. Disbanded, perhaps, before it properly completed its work. The adult Wheel Bug‘s abdomen is capacious and resembles the hull of a boat. Wings rest atop the back deck. Although Wheel Bugs can fly, they are low and slow – sputtering awkwardly like a wounded drone about to crash. At the forward end of the bug‘s hull perches an improbable armored wheel. The exact purpose of this intimidating apparatus is unknown. Perhaps it was a leftover part from some other committee project. As for the Wheel Bug‘s head? Delayed in shipping! Thus leaving the committee to make do with whatever parts were available. The result is a tiny, dowel-like head which seems far too small for the rest of the body. The good news? No expense was spared on the Wheel Bug‘s primary offensive weapons; its legs, antennae, and that all-important rostrum.
Wheel Bugs are shy creatures and are generally oblivious to humans. On foot and in the air they are clumsy and slow. They are well camouflaged and often lurk in leafy areas or places with flowers where insects abound. In ambush, the Wheel Bug uses its strong front legs to pin its victim and immobilize it. Untucking its rostrum, it stabs the unfortunate prey and injects a chemical cocktail of meat-dissolving enzymes which quickly disables the victim and liquefies its innards. A multi-purpose tool, the rostrum is then used as a straw to suck up the fresh Insect Smoothie!
For you adventurous types, below is a a short video: Wheel Bug vs Green Clover Caterpillar. 1 minute 30 seconds. Does not end well for the caterpillar.
In the past, Wheel Bug sightings were unusual. You may be surprised to know that in recent years, sightings of adult and nymph Wheel Bugs are increasing significantly in the Mid-Atlantic. Especially near homes, offices, and other man-made structures. Why? Blame it on Stink Bugs! Specifically, the invasive Brown Marmorated Stink Bug. This new item on the menu of Wheel Bugs arrived from Asia in the late 1990‘s – probably a stowaway in a cargo ship. In only a few decades, it has munched its way into 40 states, feasting on vegetables, fruits, and ornamentals.
Wheel Bugs are not picky eaters and as it happens, their adult life cycle coincides with the time of year (autumn) when Brown Marmorated Stink Bugs seek shelter for the winter. Cracks and crevices in our homes make perfect winter hide-outs for Stink Bugs! As Stink Bugs gravitate toward buildings in search of a cozy spot to escape the cold, right behind them or sometimes already waiting for them are Wheel Bugs. According to Dr. Mike Raupp of University of Maryland, with so much new prey (Brown Marmorated Stink Bugs) available, Wheel Bugs (predators) have increased their numbers accordingly. Clearly, the Wheel Bug is an insect that we must learn to live with.
HOW TO LIVE HAPPILY WITH WHEEL BUGS:
- First, let‘s talk about that bite. It can be bad. Worse than a bee or wasp sting and lasts longer. Both adults and nymphs will bite if threatened. Nevertheless, Wheel Bugs are tranquil creatures by nature and will happily ignore you unless they are threatened. Best bet is to observe but do not touch!
- Wheel Bugs are apex garden predators! Like a lion of the insect world. They are an indicator that your landscape is healthy. Be proud of them! Their menu includes caterpillars, beetles (yes, even the Japanese Beetles!), cabbage worms, tent caterpillars, Mexican bean beetles, stink bugs, aphids, cabbage worms, Colorado potato beetle, cucumber beetles, cutworms, earwigs, and tomato hornworms. The very definition of a Beneficial Garden Insect!
Wheel Bugs are here to stay. We humans can assist them by providing healthy, pesticide-free landscapes for them to live in. They, in turn, will rid our gardens of an assortment of insect pests as long as we simply leave them alone to do their work. Seems like a good bargain to me!