They're Big, but They're Not Murder Hornets
Buzz surrounding the arrival of the Asian giant hornet in parts of the Pacific Northwest has many Arizona residents on the lookout, but they're often mistaking the state's native, beneficial bugs for the potentially invasive wasp.

By Rosemary Brandt, College of Agriculture and Life Sciences
Sept. 8, 2020

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a tarantula hawk wasp on a flower
Think this is one of the now infamous "Murder Hornets"? Think again. This is a tarantula hawk, a wasp native to Southern Arizona. They're generally non-aggressive – unless you're a tarantula. Courtesy of Brad Sutton/National Park Service

"My family and I were out by the pool and we saw a murder hornet," says a voicemail left for entomologists at the University of Arizona College of Agriculture and Life Sciences. "It was definitely at least two inches and really big and scary."

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Gene Hall
Gene Hall

Messages, photos and species identification requests have flooded the college since May, with many Arizona residents reporting potential sightings of the now infamous Asian giant hornet, or "murder hornet."

The reality is a case of mistaken identity for some of Arizona's native wasps, including the cicada killer and tarantula hawk. 

"So far, the Asian giant hornet has only been found in the Pacific Northwest, specifically Washington state and British Columbia, and there is currently no indication they have strongly established in that region," said Gene Hall, who manages the University of Arizona Insect Collection.

"However, the national news attention has increased awareness of wasps, and the use of the insect's more colorful nickname has only exacerbated fears."

Murder hornets. Cicada killers. Tarantula hawks. As if their nicknames aren't scary sounding enough, their size certainly doesn't do them any favors with public opinion. Due to the large body size of both groups of wasps, people often confuse the cicada killer and tarantula hawk with the Asian giant hornet.

While UArizona entomologists encourage people to continue to be on the lookout for Asian giant hornets, Hall and his colleagues want to help provide some guidance and, hopefully, allay unnecessary fear. 

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Asian giant hornet
The Asian giant hornet's first sighting in the U.S. was recorded in northwest Washington state. Thomas Brown

Q: Cicada killers are not small and have been commonly mistaken for the Asian giant hornet. How can we tell them apart? 

A: There are a few characteristics that work for immediately separating these two groups of wasps from each other. The head of the Asian giant hornet is larger or broader than that of the cicada killer wasp. The thorax, or middle section of body behind the head, is black in the Asian giant hornet and reddish-brown in the cicada killer wasp. For the abdomen, or the third body segment, the Asian giant hornet has solid dark bands and no spotting, while the cicada killer wasp has bands wider towards the middle and spots on some abdominal segments.

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a cicada killer wasp eating a cicada
A cicada killer wasp attacking a cicada. Photo courtesy of Gerry Bunker/Massachusetts Cicadas, www.masscic.org

Q: How do cicada killers support our local ecosystems?

A: As with all species, cicada killer wasps are tied to other organisms as part of the great biodiversity of our region. Though they prey on cicadas as food for their larvae, this is part of the checks and balances of nature — two organisms that have co-evolved with each other. Undoubtedly, the cicada killer provides a high-protein meal for other organisms, including mammals and birds. Cicada killers do well in the Arizona desert since they prefer to burrow in dry soil that forms the larval chambers.

Q: What should folks do if they spot one?

A: Leave it alone. These gentle giants of the wasp world have no interest in humans; they are too busy living their lives and searching for cicadas to provide a meal for their offspring. During my 36 years studying insects of the Sonoran Desert, I've not known anybody to be stung by these wasps, plus it only would happen as a defensive mechanism.

Q: Now, tarantula hawks. What are these wasps most known for?

A: These wasps are known primarily for their interactions with tarantulas, thus the common name tarantula hawk wasp. In the same manner as the cicada killer wasp does with cicadas, the tarantula hawk wasp uses tarantulas as a food source for their developing larvae, or grubs, in underground chambers. The tarantula is paralyzed by the wasp's sting, immobilizing it while the tarantula hawk grub feeds on the large spider until ready to pupate, then emerging as an adult wasp. As with the cicada killer wasp and cicadas, the tarantula hawks and tarantulas are connected to each other in the natural cycle of life and death.

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a tarantula hawk attacking a tarantula
A tarantula hawk wasp dragging an envenomed tarantula across the ground.

Q: What are their most distinguishing characteristics?

A: The tarantula hawk is large and very conspicuous compared to most other wasps, the body being black and the wings red, orange or dark bluish-brown. Their body and wing color are completely different than that of cicada killer, so it's easy to separate the two groups of wasps from each other. I've only had a few inquiries confusing tarantula hawks with the Asian giant hornets, but that was mainly due to size of these wasps, as neither looks similar to the other.

The adult tarantula hawk will visit flowering plants, feeding on the floral nectar. They are generally non-aggressive; I've not known anybody stung by these wasps unless it was defending itself. Tarantula hawks are pollinators, and on the University of Arizona campus you can see them visiting milkweed flowers on the south side of the Chemistry Building, plus other plants on campus.

Q: These bugs pack a serious sting. How do we avoid getting stung?

A: As with all stinging insects, leave it alone. Why aggravate them? Stinging insects will generally only do so while defending themselves, a nest, their offspring or territory. If you have concerns, best thing to do is give it space and go your own way. Otherwise, enjoy the beauty of these beasts as they're a part of the amazing biodiversity inhabiting the Sonoran Desert. If possible, take time observing them in their natural habitat, learning something new about an animal you may not have noticed before. You'll see there is really nothing to fear, and in the end gain a deeper appreciation for the natural world that surrounds us.

Extra info

While the Asian giant hornet has not been found in Arizona, if residents see large wasps and are unsure, they can contact the UArizona Insect Diagnostics Clinic for identifications. For more information on cicada killer wasps, please download "Mistaken Identity: The Cicada Killer Wasp and the Asian Giant Hornet."

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Media contact:
Rosemary Brandt
College of Agriculture and Life Sciences
520-621-7182
rjbrandt@email.arizona.edu