Assassin Bug Nymph

Somewhere I’d heard that bright red bugs should be avoided at all costs, promising serious pain from bites or stings. In the case of the Cow Killer wasp this was definitely true, so when I happened upon another vividly colored red and black bug in my Black Eyed Susans I kept a safe distance.

Arilus cristatus, Wheel Bug, Assassin Bug Nymph I’d been spraying the Black Eyed Susans with my homemade antifungal for rose bushes, as my budding flowers were battling both fungus and Japanese Beetles and I feared that they’d never get to the flowering stage. A teaspoon of baking soda in a quart of water, with a few drops of liquid dish soap, is reputed to be effective against the blackspot rose fungus. I didn’t know if it would help my Black Eyed Susans but it was worth a try.

About halfway through the row, I spotted a brightly colored black and red bug that looked like a spider. Even without the bright red color, spiders are scary if you don’t recognize them, so the bug caught me off guard. On closer inspection I counted six legs, not the eight legs of a spider, with the additional pair of legs being long antennae. I figured it was probably just some common beetle, but it was interesting so I grabbed my Sony Cybershot camera figuring at the least he’d be colorful on a t-shirt.

He wasn’t as easy to find on the internet as the Saddleback Caterpillar had been, and I went through hundreds of webpages before I had absolute identification from a scientific website.

Arilus cristatus, Wheel Bug, Assassin Bug AdultMy red and black spiderlike bug turned out to be the nymph of the Arilus cristatus, commonly known as the Wheel Bug or Assassin Bug. In the adult stage he would sport a cogged half wheel on his back, giving him the name of Wheel Bug, and he’d be a non-descript greyish brown color. I probably wouldn’t have given him a second look had he reached maturity.

This particular variety of Assassin Bug feeds on many of the bad bugs that I’d been battling such as aphids and Japanese Beetles. The Assassin Bug injects enzymes into its prey which paralyzes and kills the prey within seconds. He then sucks out the juices for his tasty bug meal. Wheel Bugs are considered beneficial garden bugs as they prey on bugs that are usually considered pests, such as caterpillars, aphids, sawflies, immature locusts and other soft-bodied bugs.

Arilus cristatus, Wheel Bug, Assassin Bug Nymph Their favorite hunting grounds include trees and daisy type flowers, such as my Black Eyed Susans, and they can be found from New York to Florida, throughtout the Midwest, and as far west as California. In other words you can find them throughout most of the continental U.S. except in the far north and northwestern states.

Nymphs such as the one I discovered hatch in the spring and go through several periods of molting as they grow into adulthood. They can be vicious predators, sometimes attacking each other. After mating the female may decide to feed on the male much like a black widow spider.

The Assassin Bug emits a foul smell if disturbed much like the Stink Bug, but not quite as strong. My Assassin Bug must not have felt threatened, though he did rear up when I got too close with the camera. They are also reputed to produce chirping sounds. While these facts were interesting, what put this particular bug on my radar was the uniqueness of the eggs and the fact that yes, this was another bright red bug with a very painful bite.

Arilus cristatus, Wheel Bug, Assassin Bug EggsI’d seen pictures of Wheel Bug eggs on Paul James’ television show “Gardening by the Yard” and the egg colonies are fascinating, looking like a group of nails driven into a tree or a honeycombed beehive. From the side they are elongated brown tubes and are sometimes described as little brown bottles with fancy white stoppers. Egg clusters are found on trees, shrubs and other objects within four feet of the ground.

The other point of interest was the bite. While Assassin Bugs are not aggressive toward humans, they will definitely bite if threatened, and my fear of bright red bugs was not without merit because the bite is reputed to be quite nasty with pain much worse than a hornet sting. The area may go numb for several days and be hot to the touch, later turning white. Healing can take weeks or months, depending on the bite victim’s personal sensitivities.

Arilus cristatus, Wheel Bug, Assassin Bug NymphHome remedies for Assassin Bug bites include ammonia water, magnesium sulfate and virtually any remedy used for fire ant stings with best results if treated immediately after being bitten. Menthol, camphor and phenol may also provide relief.

The assassin bug nymph is featured in the book “Over the Hummingbird’s Rainbow: An Acre of America Backyard Nature Series” which is a back yard nature travelog with photos and stories. “Over the Hummingbird’s Rainbow” is available on Kindle and paperback.

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    3 Responses to Assassin Bug Nymph

    1. noname says:

      That is a whole year from hatching, so only one generation of assassin bugs per year. The wingless nymphs grow and molt 4 times, and in some species 7 times, over the course of the year. Adult form is achieved once the insects have wings.

    2. Myra B Wright says:

      I’m thinking this is the bug that keeps biting me when I work in the roses. the bites look very much like a mosquito bit except this bite gets about the size of a
      nickel or dime and doesn’t really start itching until the second day after it bites.
      I’m going to the doctor this week to see if he will prescribe an epic-pin for me. I am allergic to Horse flies which causes a 4 or 5 inch diameter when bitten. In the last 2 to 3 weeks I’ve been bitten about 8 times. Always on the arms and now guess I will start wearing long sleeve shirts when dead-heading the old roses. I am sure this is the same thing as it is red and black but too small to see the legs.
      Thank you for the information. Myra

      • Allie says:

        Eight times bitten, you poor thing! I cannot even imagine. They do eat aphids, so maybe that’s why he likes roses. We’ve seen them on black-eyed susans here.

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