How We Can Stop Hating Wasps

Recent studies have shown that wasps are among the most loathed of all insects. Consequently, much time and money is wasted on trying to eradicate them, especially by homeowners. Let’s consider why we have the attitudes we do, and how we can achieve coexistence with wasps.

A trio of Western Yellowjakcet workers dispatches a pest caterpillar.

Why do we hate wasps?

There are three main reasons wasps evoke fear and loathing.

• The sting. Females of some species can inflict painful stings on us tender humans. This is occasionally for self-defense, but mostly in defense of a nest full of immobile and otherwise vulnerable eggs, larvae, and pupae inside a nest. Only social wasps will bother us this way.
• Narrow definition of “wasp.” Most people equate the word “wasp” with “hornet,” “yellowjacket,” or “paper wasp.” All of these are social wasps, the ones most abundant in urban and suburban settings, and by far the ones we have the most negative encounters with. Some people recognize other kinds of wasps, particularly mud daubers, but consider their nests unsightly, a nuisance, or a potential threat. In reality, the overwhelming majority of wasps are solitary, like mud daubers, each female making her own nest, or using a host animal or plant in situ. Most wasps cannot sting people. Many cannot sting at all. Most are tiny, only ten millimeters or less in length.
• Social wasps exploit our habits and weaknesses. Yellowjackets (including the Bald-faced “Hornet,” and paper wasps make their nests in and around our homes and buildings. This is because our architecture mimics the cliff faces, rock overhangs, and natural hollows where they nest “in the wild.” A few yellowjacket species are scavengers, and your barbecue or picnic resembles an abandoned animal carcass that can be exploited. The wasps take protein matter back to the nest to feed their growing larval siblings. Meanwhile, your open soda or beer container offers sugary carbohydrates the adult wasps need to fuel their flight muscles. We like to think we are masters of our domain, or at least our private property, and wasps defy that desire with maddening efficiency.

Most wasps, like this "fairyfly," are tiny, solitary, and don't sting people.

Benefits of Tolerating Wasps

Positive outcomes from tolerating wasps, or even accommodating them, far outweigh any perceived benefits of eradication or control, excepting rare cases where you or another family member has hypersensitivity to insect venom, and there is demonstrable risk of a life-threatening incident.

• Saving money on products or services. This point is seldom made when arguing against the use of DIY pest control products, or the employment of professional pest control services, but it can be of profound financial consideration. Prevention is easier and more effective. More on that in a moment.
• Wasps are a pest control service. Most social wasps, even those that scavenge occasionally, are predatory on insects that are problematic in our yards, gardens, barns, and sheds. Solitary wasps are parasitoids of even more species that can be truly pestiferous. Among the hosts for wasps are caterpillars that eat garden plants, aphids that suck plant sap, flies that can potentially spread bacteria, cockroaches both outdoors and indoors, and spiders. There is scarcely any terrestrial arthropod that is not host to at least one wasp species.
• Wasps are pollinators. Technically, most wasps are “flower visitors,” coming to blossoms for nectar to fuel their flight muscles. They still effect pollination services, and there are some species in western North America that are obligate pollinators of certain wildflowers.
• Wasps dispose of animal carcasses. Those scavenging yellowjackets make quick work of the remains of small animal carcasses that vultures and other vertebrate scavengers ignore or cannot find. This prevents the accumulation of decaying animal matter, lessens risks to human health from problematic bacteria, and prevents explosions of filth flies that would otherwise use those dead animal resources.
• Wasps are a source of fascination and intrigue. Wasps can be easily and safely observed as they go about their activities of host-seeking, flower-visiting, and nest-making. You will be surprised by how many wasp species are living in obscurity in your yard and garden. Watching them will reveal amazing relationships with many other organisms.

Paper wasp nests can be safely observed and offer hours of fascination.

How do we get along?

We can prevent most negative encounters with wasps by taking a few precautions. It will literally save you physical pain and financial discomfort.

• Learn wasp body language. Paper wasps, the ones that make uncovered paper combs under eaves, in door and window frames, and elsewhere, are usually amicable neighbors. If you do approach a nest too closely, one or more wasps will stand on tiptoe and flare their wings. This means “back off.” You risk being stung if you ignore that warning.
• Inspect your yard regularly. Too often, underground yellowjacket nests, or those above ground, hidden in shrubs or rock walls, are not discovered until the lawnmower runs over one, or the hedge trimmer triggers an attack. Inspect your property thoroughly, including playground equipment, before using tools, or otherwise causing any strong vibration in the vicinity of a social wasp nest. It may take a little patience and keen observation to note the streams of wasps coming and going regularly from a specific location. Your kids may see them before you do.
• Serve beverages outdoors in clear glass or plastic.
Unattended beverages that are sweet or fermented will attract yellowjackets and other wasps that may crawl inside the container. Cans and opaque bottles mean that you will not notice a wasp inside. A sting to the tongue or throat can be a life-threatening experience regardless of whether you are allergic to stings.
• Cover food served outdoors. When not serving yourself or others, cover meats and sweets at the outdoor gathering. You can also set out a small, exposed plate of meat a good distance away from the serving table, to draw yellowjackets away.
• Seal cracks and crevices. To prevent wasps from nesting indoors, or seeking shelter in the winter, seal cracks and crevices. Mend holes in, or replace, window screens. Screen the attic vent with fine mesh. Replace worn weatherstripping around doors. This will help save on heating and cooling costs, too.
• Learn to recognize solitary wasps. Many wasps that are solitary may behave as if they are social. A large number of wasps flying low over your lawn are likely male wasps looking for females that have yet to emerge from the ground. An ominous gathering of iridescent blue mud daubers in a door frame at dusk means that males are bedding down for the night in a large group. Male wasps do not sting. Cicada killers are huge wasps, but solitary. Females may nest close together, making them appear social. Males keep watch over them and may fly “aggressively” to chase away any and all intruders. It is all bluff.

More information about wasps can be found in this blog, in my book Wasps: The Astonishing Diversity of a Misunderstood Insect, and elsewhere. Online, the most reliable sources remain college, university, and museum websites with a “.edu” or “.org” suffix in the URL. Thank you in advance for sharing a link to this post in social media, neighborhood groups, and other outlets.

A solitary thread-waisted wasp with a caterpillar she stung into paralysis. It will be food for her single larval offspring at the bottom of an underground burrow.

Sources: Schmack, Juila M., Monika Egerer, Susan Karlebowski, Astrid E. Neumann, and Ulrike Sturm. 2024. “Overlooked and misunderstood: how urban community gardeners perceive social wasps and their ecosystem functions,” Journal of Insect Conservation.

Book Review: The Social Wasps of North America

Chris Alice Kratzer’s new guide to The Social Wasps of North America stands to revolutionize the future of field guides. It certainly sets a new standard in many ways, through methodology, organization, and sheer honesty. It is my pleasure to recommend this wonderful reference without reservation.

This is a self-published book from Owlfly Publishing, one arm of Kratzer’s company, Owlfly, LLC. The other branch is an engineering firm. Kratzer has not only avoided all the usual pitfalls of self-publishing, she has taken great pains to make every aspect of that enterprise respectful and sustainable, right down to her choice in the packaging vendor she uses.

Why is this book so unique and important? Perhaps the most obvious feature is the geographic coverage. Kratzer rightly defines North America as everything north of South America. Most natural history publishers, and authors, would consider that to be overly ambitious, confusing, and impossible to execute given the increased biodiversity south of the Mexican border. It helps to choose a taxon that has relatively limited diversity, and social wasps in the family Vespidae do fit the bill nicely. However, one should not overlook the statement this book makes about inclusiveness. This book is useful to indigenous peoples in those other nations, as well as people traveling from other places. A Spanish translation, in digital format, will be available by the end of 2021, but if a publishing house is interested in producing a hard copy, please contact Kratzer at Owlfly Publishing.

This book also marks a return to illustrations, rather than photographs, as the best means to visually communicate each species. Kratzer is a master of digital renderings. Social wasps are maddeningly variable in color pattern, so she ingeniously fused the most common xanthic (mostly yellow) and melanic (mostly black/dark) forms of each species into a single drawing, capitalizing on the bilateral symmetry of her subjects to do so. Brilliant. Kratzer essentially crowdsourced her references by utilizing pinned specimens from many curated collections, and images of living specimens from the iNaturalist web portal. She gives credit to every single individual who furnished the material. Unheard of. Each species account includes female and male examples, plus queens, where relevant. Range maps are included. Photos of living specimens, and their nests, are featured under descriptions of the genera.

© Owlfly LLC

The first seventy or so pages of the book serve as an introduction and overview of social wasps, their biology, role within ecosystems, and how they impact humanity. This alone is worth the price of the book. The writing is outstanding in accuracy and honesty:

“All of the information in this book is wrong. All of it. Wasps are an appallingly understudied group of organisms, to the point that even this book – the most complete visual guide of social wasp to date – is built precariously upon the edge of a vast, unsolved jigsaw puzzle.”

The grammar is impeccable, and the tone is exceptionally friendly and empathetic, even to those readers who want nothing to do with wasps. It is easy for someone with an affinity for maligned animals to be unintentionally hostile towards those who do not share the same perspective and opinions. Kratzer is going to make many more “friends of wasps” with this book. Did I mention that there is also a glossary and extensive bibliography with links to online versions of actual scientific papers?

Overall, Kratzer’s embrace and navigation of the scientific ecosystem, inclusive of both academic professionals and well-informed non-professionals, is admirable and even ground-breaking. Rarely does one find a reference or author/illustrator so worthy of emulating. Maybe David Sibley and Kenn Kaufman, but add Chris Alice Kratzer to the list.

Are wasps not your thing at all? Stay tuned for Kratzer’s next effort, a guide to North American cicadas, in the works as I write this. Meanwhile, order The Social Wasps of North America for a friend, directly from Owlfly Publishing.

One of These is Not Like the Others....

Sometimes, even with your book-learned knowledge, it takes you a moment to recognize something when you see it firsthand. Such was the case when my wife and I encountered a softball-sized nest of the Aerial Yellowjacket, Dolichovespula arenaria, under the eave of a small building in Green Mountain Falls, Colorado, on July 10. Worker wasps were coming and going as they should, but another wasp was periodically emerging, too, and it was not like the others.

The other wasp was larger than the workers, and instead of being black and yellow, it was black and white. It eventually dawned on me that I was witnessing a social parasite in action. The black and white wasp was a female Dolichovespula arctica (aka Dolichovespula adulterina). Her species has no worker caste like the Aerial Yellowjacket, only reproductive females, and males.

The Aerial Yellowjacket is the primary host species for this social parasite. The D. arctica female infiltrates an existing colony of the host, when it is underway but before worker wasps have emerged from the pupa stage. The parasite does not usually kill the host queen immediately, but waits until she has produced a fair number of workers. She may also evict the queen, or follow her around and eat the eggs she lays in the cells of the paper comb. By the time workers of the host species have matured, they serve as a workforce to raise the offspring of the social parasite. It is a subtle form of slavery of which the host species seems unaware.

Why the female D. arctica repeatedly emerged from the interior of the nest to wander around on the exterior paper envelope is a mystery to me. Perhaps the workers tolerate her only for short periods, and her foreign scent would overwhelm the normal colony odor if she lingered longer inside?

The parasite is probably fairly common, but seldom seen. The species ranges from Alaska and throughout Canada save for the Nunavut Province, south to the northern U.S. and along major mountain ranges to Kentucky, Georgia, Arizona, and California. It appears to be limited to high elevation coniferous forest habitats here in Colorado; and that is probably the case over much of the United States.

Lest you feel saddened about the fate of the host colony, remember that worker yellowjackets are still capable of laying unfertilized eggs that ultimately give rise to males of the species. So, the host colony can still reproduce, but is limited to liberating only males during the late summer reproductive season.

Take a moment when you encounter insect activity, what it reveals over even a short period of time may surprise you. Even nests of social wasps can be approached quite closely, as long as you do not jar the nest or otherwise create hostile vibrations. I had to get very close with my camera because my flash was not working. Not once was I even harassed by a worker wasp.

Sources: Akre, Roger D. et al. 1980. Yellowjackets of America North of Mexico. U.S. Department of Agriculture, Agriculture Handbook No. 552, 102 pp.
Buck, M., Marshall, S.A. and Cheung D.K.B. 2008. Identification Atlas of the Vespidae (Hymenoptera, Aculeata) of the northeastern Nearctic region. Canadian Journal of Arthropod Identification No. 5: 492 pp. (PDF version). Published on 19 February 2008.
Evans, Howard E. and Mary Jane West Eberhard. 1970. The Wasps. Ann Arbor: University of Michigan Press. 265 pp.

Eight Illinois Wasp and Bee Mimics in Twenty Minutes

One of the few entomologically-rewarding stops on our recent road trip was at the National Trail Rest Area on Interstate 70 near Altamont, Illinois, on May 16. A brief bit of sunshine warmed the woodland edges enough to bring out a wealth of fly diversity, many of which were mimics of various wasps and bees. There were even a few real wasps.

Somula decora syrphid fly

Large patches of touch-me-nots (aka "jewelweed") carpeted the edges of the lawn where it gave way to forest, and the leaves of this plant offered places to bask for many insects. The first fly I spotted was one of my favorites in the family Syrphidae (flower flies). Somula decora is roughly the size of a honey bee, black in color but heavily marked with golden yellow. I suspected that this species is a mimic of scoliid wasps, but at this time of year a more likely candidate for a model would be a queen yellowjacket.

Helophilus sp. syrphid fly

Helophilus spp. are also probably yellowjacket mimics. The vertical yellow stripes on the thorax help to identify them fairly easily. Apparently the larvae develop in decaying plant matter that is submerged in water, as do other Syrphidae species like the "rat-tailed maggots." The adults certainly are sun-loving as their genus name suggests.

Temnostoma sp. syrphid fly

Syrphid flies in the genus Temnostoma are likely mimics of the solitary mason wasps that are in the same family as the social yellowjackets. They carry their mimicry to astonishing extremes. Note that the leading edge of their wings is darkened, mimicking the longitudinal folds of a vespid wasp's wings at rest. Wasps have long, reasonably thick antennae, which Temnostoma flies don't have. No worries, the fly compensates by waving its front pair of legs in front of its face, just like wasp antennae. Wh-a-a-a-a-t?! I know! Next time I'll take video.

Male Ancistrocerus sp. mason wasp

Well, lookie lookie, here comes an honest-to-goodness, certifiable mason wasp. This is a male, as the tip of each antenna is hooked, a distinguishing characteristic for many male eumenine wasps. I am a little hard-pressed for a genus, but I suspect it might be Ancistrocerus. Female mason wasps usually nest in pre-existing cavities like old beetle borings in logs, hollow twigs, etc.

Chalcosyrphus piger syrphid fly

Yet another kind of syrphid fly we saw was this Chalcosyrphus species. They are typically assumed to be mimics of solitary wasps in the families Pompilidae, Crabronidae, or Sphecidae. Indeed, some species even flick their wings like wasps while they run around on foliage or the surface of logs. Their larvae live in decaying wood, but at least a few may feed on fermenting sap. This species has a red abdomen, but others are wholly black or otherwise colored differently. There are 22 species in North America, so identification is difficult without putting a specimen under a microscope.

Xylota sp. syrphid fly

Closely allied to Chalcosyrphus is the genus Xylota. Oddly, this specimen reminded me most of a sawfly or an ichneumon wasp, neither of which is usually capable of stinging in self-defense. The adult flies rarely visit flowers, instead feeding on pollen grains from the surface of leaves. The larvae develop in rotting wood.

Mallota posticata syrphid fly

Many syrphid flies use leaves as a platform on which to groom, which explains the yoga-like moves of this specimen of Mallota posticata, a bumble bee mimic. I swear, grooming flies must be the envy of contortionists. As larvae, these flies grow up in rotting holes in trees.

Eastern Yellowjacket queen, a real wasp!

My, my, here we have another actual wasp, a queen of the Eastern Yellowjacket, Vespula maculifrons, pausing from her search for an underground nesting site. She is likewise grooming. This particular species is very likely the "model" for most of the "mimic" flies we were seeing....and arguably the best mimic was yet to come.

Sphecomyia vittata syrphid fly

The syrphid fly Sphecomyia vittata is simply stunning. It is about the same size as a queen yellowjacket, and even has longer, thicker antennae than almost any other fly, the better to resemble its sting-equipped model. This insect even flies like a queen yellowjacket, in the lazy, zig-zag manner of a queen looking for a nesting site. I recall capturing one of these in Cincinnati and being convinced it was a wasp right up until I had it in the jar. I was jaw-droppingly impressed.

Ichneumon wasp

Ah, here is an ichneumon wasp that looks suspiciously like that Xylota flower fly we saw a few minutes ago. At least some members of the subfamily Ichneumoninae can sting, so maybe looking like one is a better strategy than first imagined.

Laphria sp. robber fly

Somewhere along the line my wife spotted this fly, which I never saw. It is obviously a bumble bee mimic, but it is not a syrphid. It is a robber fly in the family Asilidae, genus Laphria. Looking like a bumble bee works to its advantage in two ways: its potential predators assume it stings. Meanwhile the fly's potential prey assume it is a bee seeking flower nectar. Interestingly, Laphria seem to be particularly fond of small, flying beetles, which they spot from their perches, apprehend in mid-air, and return to a leaf or log to feed upon.

Common Gartersnake, Thamnophis sirtalis

What a rewarding rest stop. Oh, and there was this bonus Common Gartersnake, Thamnophis sirtalis, also soaking up some rays. It never moved an inch as we worked around it to take insect images. Thanks to the maintenance crews at this rest stop for recognizing the importance of leaving natural elements intact around the area, including dead wood for insects to feed on, and birds to nest in. May other states follow your example.

Source: Marshall, Stephen A. 2006. Insects: Their Natural History and Diversity. Richmond Hill, Ontario: Firefly Books, Ltd.732 pp.

Makin' Paper

This has been an exceptional year for paper-making social wasps in the family Vespidae here along the Colorado Front Range. Most species of paper wasps and yellowjackets have been unusually abundant, much to the consternation of the average person who despises any stinging insect. However, there is much to admire about these industrious organisms, not the least of which is the amazing architecture of their nests.

Western Paper Wasp nest (Mischocyttarus flavitarsis)

Nests of most social vespids are made of repurposed or recycled cellulose from dead, woody plants and trees. The wasps manufacture the paper by scraping fibers and chewing them into a ball of pulp that is taken back to the nest and applied as a thin strip that soon dries into a surprisingly durable, stiff material.

Bald-faced Hornet worker scraping wood fibers

Paper wasps in the genera Polistes and Mischocyttarus here in Colorado make exposed paper combs that are frequently suspended under the eaves of buildings. Yellowjackets, including the Bald-faced "Hornet," Dolichovespula maculata, house their combs within a layered paper envelope. Species in the genus Dolichovespula build their nests above ground, usually in a tree, shrub, or among berry canes. Species in the genus Vespula normally build their nests underground in abandoned rodent burrows and other pre-existing cavities that they can expand by excavating around the nest.

Huge European Paper Wasp nest

I was surprised to find out that paper wasps will re-use old nests! One particularly impressive nest of European Paper Wasps (Polistes dominula) is situated under an overhang at my workplace in Colorado Springs. It appeared abandoned when I first started work there, but was quickly occupied and even expanded later in the season. This is an impressively large nest that would probably not fit on a dinner plate, very unusual for any species of Polistes.

Active nest of Bald-faced Hornets

I also discovered an active nest of the Bald-faced Hornet in North Cheyenne Cañon on August 21. Fortunately, it was far enough off the trail to not be a potential hazard to the many people that use the park; and far enough off the trail to make it difficult for anyone to destroy the nest. I went back a month later (September 18) and found the wasps had expanded the nest and changed its shape from oval to a roughly football shape. There was no evidence of activity, and indeed the colony cycle for this species is shorter than that of other social wasps.

Bald-faced Hornet nest on August 21

The same nest on September 18

Underground nests like that of the Western Yellowjacket (Vespula pensylvanica) and Prairie Yellowjacket (V. atropilosa) are more problematic because one can easily disturb an unseen nest with painful results. I only notice nests when my eye catches a steady stream of yellowjackets coming and going from a common point.

Western Yellowjacket nest entrance. Note exiting workers carrying soil pellets

Paper wasps are generally welcome predators of caterpillars and other soft-bodied insect pests. The Bald-faced Hornet is a predator of flies that is never a pest at picnics and barbecues. The same is true of the Prairie Yellowjacket. Meanwhile, the Western Yellowjacket is a scavenger that will take your lunch away from you given the opportunity. Gently waving your hand can eventually discourage the wasp's efforts.

Prairie Yellowjacket worker eating insect

We may have these wasps to thank for inspiring the invention of the paper that we use today. At least some accounts trace observations of wasps in ancient China to the origins of human papermaking.

Wasp Wednesday: Prairie Yellowjacket

Arriving in Colorado Springs in early October, I was not optimistic that I would find many, if any, wasps still active in the chilling air. Much to my surprise there are still some on the wing, even at high altitudes. Monday, October 10, Heidi and I traveled up into the Front Range to Cripple Creek and the surrounding area. There, walking around on the snow, I found a male Prairie Yellowjacket, Vespula atropilosa.

Heidi remarked that she thought the Western Yellowjacket, Vespula pensylvanica was the only species of that genus living in the area. Actually, there are six species total known from Colorado. Yellowjackets could be considered mostly boreal in their distribution patterns, ranging south at higher elevations where the climate resembles that of higher latitudes.

This particular specimen could have been blown up to its 9,000 foot or so location, too. The colonies of V. atropilosa tend to be smaller than those of more “urban” species, and usually decline earlier in the season, too, so I was somewhat surprised to see this one.

This male exemplifies the yellow or “xanthic” phase of this species. They also come in a black or “melanic” phase that is more black than yellow, as shown in the diagram below from Roger D. Akre’s The Yellowjackets of America North of Mexico (USDA Agriculture Handbook No. 552, 1981), and another specimen I imaged on October 13 in Colorado Springs.

The Prairie Yellowjacket nests preferentially in abandoned rodent burrows. Nests have also been discovered in tree hollows, under steps, and between the walls of houses. One truly aerial nest was found in Pullman, Washington, but this is decidedly an anomaly. The paper combs are surrounded by layers of “envelope,” typically rather coarse as is the case in most subterranean yellowjacket species. V. atropilosa nests are dirtier than most, with the bodies of deceased wasps and other debris incorporated into the paper envelope.

The greatest number of workers in any of the nests studied by Dr. Akre and his colleagues was 504. These are not your picnic-harassing, garbage-gathering yellowjackets, either. They have retained their predatory nature and hunt mostly spiders, harvestmen, flies, insect larvae, and true bugs as food for the larvae back in the nest. Adults feed on aphid honeydew and flower nectar to fuel their flight.

The Prairie Yellowjacket is restricted to western North America, ranging from central British Columbia south and east through southern Alberta, Washington, Oregon, California, Idaho, western Montana, Wyoming, Utah, most of Colorado, and northern New Mexico and Arizona. It avoids nesting in truly urban locations in my experience, though nests in yards are apparently not uncommon.

I look forward to finding more interesting yellowjacket species here in the Rocky Mountains, and I reserve the right to revisit this particular species in future blog posts.

Wasp Wednesday: Not Wasp III

When it comes to mimicry of wasps, the flower flies of the family Syrphidae are perhaps unequaled. They are convincing enough that I myself remain prone to being fooled by some of these imposters. Among the best of the best are members of the genus Spilomyia, which not only look like yellowjackets, but even sound like them.

A recent trip to Colorado Springs, Colorado revealed just how easy it is to pull the wool over my eyes. At the Cheyenne Mountain Zoo I had been seeing both Aerial Yellowjackets (Dolichovespula arenaria) and Western Yellowjackets (Vespula pensylvanica) licking aphid honeydew off of leaves on a young aspen tree. One of the “yellowjackets” didn’t look quite right, though, and a closer inspection revealed it to be a fly.

One way I am able to tell flower flies from yellowjackets is by the antennae. Yellowjackets have long, thick antennae, whereas most of the flies have very short antennae with a hair-like appendage called an arista on the very tip. Some flower flies, including those in the genus Spilomyia compensate for this difference by waving their front legs in front of their faces to simulate the longer, thicker antennae of the wasps.

Fine. I can always tell the difference by the eyes. Flies have very large eyes that meet at (males) or near (females) the top of their heads. This should be easy. Ok, wait a minute, exactly where do this fly’s eyes end and the rest of its face begin? Swell. The ornate black and yellow markings on the fly’s eyes now make sense: they break up the outline of the eyes, making them appear smaller than they actually are.

Alright, I don’t give up that easily. Flies have only one pair of wings, while wasps have two. Ha! I got you now. Also, the wings of yellowjackets are folded longitudinally when the wasp is at rest, so the wings appear thinner and darker….Uh oh. This fly actually has the front half of each wing darkened to mimic that fold. Unreal.

The flies are also the same size as yellowjackets, varying from 12-17 millimeters in body length. But, as if visual appearance and behavior are not enough to convince a would-be predator not to mess with the fly, this mimic even sounds like a wasp. The frequency of its wingbeats in flight is nearly identical to that of its yellowjacket model. One has to wonder if any predator or parasite can see (and hear) through this charade.

Flower flies are more than just a pretty face, though. The adults visit flowers, and they can be at least adequate pollinators as a result of this behavior. The larval stages of Spilomyia apparently dwell inside water-filled tree holes, feeding on decaying organic matter. So, they are valuable recyclers and decomposers, too.

The next time you think you see a yellowjacket in your yard or garden, do a double-take; maybe a triple-take. You might just be seeing a fly in disguise. Spilomyia is a very widespread genus with about 13 species in North America, so chances are good that they are in your neighborhood.