Flying Ants

I recently came across a male specimen of the "legionary ant" Neivamyrmex nigriscens while walking our dog in our Colorado Springs neighborhood. It was instantly recognizable to me, but it got me thinking about how most people would be hard-pressed to know what it was. Unfortunately, there are very few references for the identification of winged ants. This is a shame because it is often the "alates," males and winged queens, that are most obvious to the public.

Male Legionary Ant, Neivamyrmex nigrescens, Colorado

Indeed, worker legionary ants are mostly subterranean and nocturnal in their habits (nomadic, raid the nests of other ants to prey on the larvae and pupae), so hardly ever observed by the average person. Meanwhile, a homeowner may not notice he or she has an ant "problem" until the colony swarms, liberating a cloud of alates.

Alate queen carpenter ant, Camponotus sp., Colorado

Alates are typically larger than the worker caste of wingless, sterile females, so are more noticeable for that reason as well. In many cases, the winged reproductives resemble the workers in general appearance, but this is not always the case. The thorax of winged ants is frequently greatly expanded to accommodate the muscles that operate the wings, giving males in particular a distinctive "hump-backed" appearance.

Male carpenter ant, Camponotus sp., Massachusetts

Swarms are usually seasonal, and triggered by changes in day length, relative humidity, and air pressure, especially in the arid southwest U.S. where the onset of the monsoon rainy season sparks many ant species to swarm. These emergences can be spectacular events. Worker ants open new exits from nests in the soil, and scour the immediate vicinity to rout any potential predators and parasites.

Red Imported Fire Ant swarm, Solenopsis invicta, Georgia

Many swarm events take place in late afternoon, at dusk, after dark, or at dawn. Winged ants may be attracted to outdoor lights, which can lead to the assumption that the ants came from the house or building when that is not necessarily the case.

Colonies of a given species in a localized area swarm simultaneously such that members of different colonies can find each other and increase genetic diversity while decreasing the potential for inbreeding. Winds, and the insect's own muscle power, can take the ants far from their colony of origin.

Rough Harvester Ant swarm, Pogonomyrmex rugosus, Colorado

How do you know whether it is a winged ant or a winged termite? Please read my post on termite swarms for a concise explanation, and images of winged termites. Below is an image of a winged termite to compare to the ants illustrated here.

Alate dampwood termite, Zootermopsis laticeps, Arizona

What about wasp versus ant? That is a more problematic distinction, but most ants have distinctly "elbowed" antennae, whereas wasps often do not; or at least the first segment of the antenna is not as long as it is in ants. There are exceptions, of course, like the male Neivamyrmex ant shown at the top of this post that has no obvious elbow in the antennae.

Male Pavement Ant, Tetramorium sp., Colorado

Fortunately, I am not the only one who recognizes the need to pay more attention to alate ants in terms of research and public awareness. Laurel Hansen and Art Antonelli include a key to alates in their publication, listed below. Brendon Boudinot, in a guest post for Alex Wild's Myrmecos blog, extols the virtues of studying male ants for a clearer understanding of the phylogeny of the family Formicidae.

Alate queen thatching ant, Formica sp., Colorado

Sources: Boudinot, Brendon. 2013. "Male Ants Demystified," Myrmecos.Hansen, Laurel, and Art Antonelli. 2011. Identification and Habits of Key Ant Pests in the Pacific Northwest. A Pacific Northwest Extension Publication 624. Pullman, WA: Washington State University. 14 pp.
Houseman, Richard M. 2008. "Ants." University of Missouri Extension.

Life in a Paper Palace

Back in the 1980s I began my writing career as a volunteer with the Audubon Society of Portland (Oregon). A group of us produced an award-winning publication called The Urban Naturalist. I thought it might be interesting to visit some of those old articles, like this one in the spring, 1987 issue.

It is a battle royal. Queen versus queen, locked in deadly combat with gnashing jaws and jabbing, venomous stingers. A scene from a science fiction soap opera? Alexis versus Crystal? No. At stake is a kingdom of social wasps and the beginning of an annual dynasty.

While most wasps are solitary, the yellowjackets, hornets, and paper wasps are colonial. No true hornets occur in Oregon, but six species of yellowjackets thrive in the Portland area. All belong to the family Vespidae. Three types of adult wasps are present in a mature colony: one reproductive female or queen, many subordinate females called workers, and males or drones. Each princess and prince begins life as an egg, laid in a single, hexagonal paper cell. The egg hatches into a hungry, white larva. Workers feed the grub protein in the form of chewed-up insects or pieces of carrion. The larva grows rapidly, eventually filling its confining cell. Soon, the larva weaves a silken dome over its cell and transforms into a pupa, the resting stage in which its organs are miraculously rearranged into those of an adult wasp. The full-fledged insect then chews off the cap on its cell and emerges.

The entire colony goes through a similar life cycle, beginning in early spring. Not every nest has a violent genesis, but real estate is hard to find and competition is keen. If fate leads a queen to a site already occupied by a nest, she may engage the resident queen in a duel to the death.

Once established, the royal family can grow and prosper through the summer, wrapped inside an architectural masterpiece. The marvelous combs of cells, where the offspring develop, are made wholly of wood fibers, chewed into a papery pulp and mixed with saliva. The combs are stacked, connected by sturdy paper pillars. A multi-layered paper envelope encloses the combs to insulate and complete the durable castle.

The workers expand and repair the elaborate structure, and also defend themselves and nestmates, using their needle-like stingers liberally. Some species can even spray their venom! Only the females possess a stinger which is evolved from the ovipositor, an egg-laying organ. If a battle between queens leaves a young colony orphaned, workers can even produce progeny themselves. Normally, the presence of the matriarch suppresses the reproductive potential of the workers. In her absence, they may lay unfertilized eggs which give rise to males!

The population of a typical colony peaks at a few hundred to several thousand royal subjects when new queens and males mature in the late summer and early fall. They are not accorded the pomp and circumstance granted a royal wedding, but the brief nuptial flights serve their purpose of procreation. Afterwards, the males soon perish.

Male Western Yellowjacket

With the departure of the queens, including the founding mother, the empire begins to crumble. The workers, normally passive, become highly agitated, attacking other creatures without provocation. They may cannibalize the larval wasps remaining in the nest, or simply throw them out.

The kingdom they created with such care, they now seem to destroy with ruthless determination, reminiscent of the deterioration of the Roman empire. For yellowjackets, though, there is a resurrection. After mating, the queens seek appropriate places to spend the winter in hibernation. Most often they hide under bark on stumps and logs, curling their legs and wings beneath them. They awake the following spring to initiate their own colonies.

Be on the lookout for yellowjacket nests overhead and underfoot. The baldfaced “hornet,” Dolichovespula maculata, builds its enormous nests among blackberry canes, low in trees, and shrubbery. Some of these structures are as big as basketballs! Thankfully, the occupants are gentle in nature. Most importantly, these large black and white wasps kill great numbers of flies to feed the larvae in the nest. Sometimes, they prey on other yellowjackets, too.

D. arenaria also builds above ground, often suspending its aerial palaces from human dwellings. The nests, and the wasps themselves, are usually small. These are yellowjackets in the truest sense, colored in alternating bands of black and yellow. They, too, prey on other insects to feed their younger siblings.

By far the most abundant and pesky species is the Western Yellowjacket, Vespula pensylvanica. Large colonies of this wasp live in subterranean nests, built in abandoned rodent burrows, rock walls, and similar cavities. What makes them a nuisance is their habit of scavenging for foodstuffs at picnics, in garbage cans, and other urban situations.. They are predators, too, sometimes killing honeybees to feed on the nectar stored in a bee’s gut. They also will swarm over ripe fruit to feed on the juices, and sip the honeydew secreted by aphids and scale insects.

The Common Yellowjacket, V. vulgaris [Edit: now V. alascensis], is very similar to the Western Yellowjacket in size, color, and habits. It, too, often feeds on carrion and human foodstuffs and becomes a pest.

Prairie Yellowjacket queen (center) with "xanthic" (yellow) and "melanic" (black) workers

V. consobrina, the Blackjacket, resembles a smaller version of the Baldfaced Hornet, being black with sparse white lines. These scarce insects live in small colonies underground and are strictly predatory.

The Prairie Yellowjacket, V. atropilosa, is also an uncommon predator.

Yet another species will likely invade Portland this year. The German Yellowjacket, V. germanica, was originally introduced to the eastern U.S. from Europe. Besides being slightly more aggressive than native species, it has a tendency to nest in houses, between the walls! Isolated colonies have been discovered in California and western Washington, especially along the I-5 corridor. Traffic to Expo ’86 is probably responsible, at least in part, for ferrying this unwelcome immigrant to the Northwest.

Should it be necessary to remove a nest, one can do so with constructive consequences. At least one lady, Betty Pope of Rivergrove, Oregon, will rid you of problem colonies by freezing their female tenants. Their bodies can then be processed into extracts used in the treatment of stings in hypersensitive victims.

On the whole, yellowjackets are beneficial organisms. They dispose of large numbers of pest insects, and also help pollinate flowers. Studying their social behavior may shed some light on human relationships. We may learn that their mysterious population booms and busts are a metaphor for man, a disturbing thought tempered only by the reminder that yellowjackets have learned to cope successfully in an ever-changing world.

I see I had a flair for the dramatic back then. What else has changed? Entomologists were not as easily accessible back then, before personal computers and the internet. I had to use a typewriter and the telephone, and the library.

Polistes metricus

Paper wasps tend to be quite variable in color and pattern, even within one species, so identifying them is not easy, even for experts. Case in point is differentiating the common Northern Paper Wasp, Polistes fuscatus, from the very similar Polistes metricus.

Dark specimens of the Northern Paper Wasp are nearly identical to Polistes metricus, a consistently dark species that I have found to be less abundant than P. fuscatus in areas where their geographic ranges overlap. One fairly reliable, if subtle, clue is the shape of the abdomen. Note that the abdomen of P. metricus is highly convex on the underside, creating a nearly acute angle with the underside of the petiole (stalk-like segment connecting abdomen with thorax). This is usually much less pronounced in P. fuscatus.

Another difference is in the face of the female wasps. Females of P. metricus have an almost completely red face, the black markings confined to the ocellar triangle. Ok, so what is an “ocellar triangle?” Most wasps have a trio of tiny, “simple” eyes at the top of the head, between the large compound eyes. These simple eyes are usually arranged in a triangular pattern. Females of the Northern Paper Wasp have the black marking extended from the ocelli to the base of the antennae. Males of both species have square, yellow faces.

Female P. fuscatus. Note black face; gently curved venter of abdomen
Female P. metricus. Note convex venter of abdomen.
Female P. metricus. Note all-red face.

Polistes metricus ranges from extreme southwestern Ontario and Maine south to Florida, and west to southern Ohio, Nebraska, Kansas, Oklahoma, and eastern Texas. The Northern Paper Wasp has a much larger geographic distribution.

I was fortunate enough to find three embryonic nests of P. metricus on a recent trip to Missouri. Two nests were under the exterior of a recessed door frame in Excelsior Springs. The other was under the roof of a sign and kiosk at Little Dixie Lake Conservation Area west of Kingdom City. These are typical nesting sites, though they can also be built among shrubbery and other more exposed locations.

Both the Northern Paper Wasp and P. metricus prey mostly on caterpillars, chewing up the larvae and feeding them to their own grubs back at the nest. Look for the adult wasps on flowers as they fuel themselves on nectar. They can also be seen around aphid colonies, lapping up the “honeydew” secreted by the aphids as a waste product.

Source: 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).

Wasp Wednesday: Wasps in a Bubble

One of the strangest inquiries I have ever received was the image below, from a Facebook friend named James Adams. He took the picture at the Rio Santiago Nature Lodge near Santa Ana, Honduras (northern coast). Not familiar with the tropical fauna there, I forwarded the image to Dr. James Carpenter at the American Museum of Natural History in New York City. Dr. Carpenter is a world authority on social wasps with much experience in the neotropics.

© James Adams

Here is the original post to James Adams’ Facebook page:

”OK so this is one of the weirdest things I've seen in nature. These small, black wasps created a normal-looking nest amidst leaves of a soursop tree. Then either they, or some other creature, encased the entire thing in this "plastic" bubble. Great protection from the rain, but WTH ????? There's a little oval-shaped hole in the bottom so they can get in and out. Anyone like Court Whelan or Deborah Matthews know what these wasps are called? Crazy! Rio Santiago Nature Resort, Honduras —“

Dr. Carpenter wrote the following in response to my query:

"It's a nest made by a species of Protopolybia. There are several species in the Amazon that make envelopes of "wax paper," such as chartergoides - you may encounter descriptions in the literature under the generic name Pseudochartergus. The paper that paper wasps make is most commonly wood fiber bound with saliva - these critters have just left out the wood."

The other comments on the original Facebook post of this image were delightful. Piotr Naskrecki, an extremely experienced explorer in his own right, said “Absolutely amazing, I have never seen anything like this.” Holly Overmyer was jealous: “I wish I could make a little plastic bubble when I get caught in the rain.” John Afdem quipped: “I'm just guessing here, but perhaps its one of the Saranwrapipedes???” Kenneth Barnett, not to be outdone, replied “John, you must talking about Polyrapus opaqous?”

James Adams runs The Lodge at Pico Bonito, La Ceiba, Atlantida, Honduras. I just may have to visit both nature lodges to see this kind of phenomenon for myself.

Wasp Wednesday: A Tropical Social Wasp

Attention: You. Yes, you. I welcome your images of mystery insects and spiders from anywhere in the world, and will blog the answer to share with others if I have your permission to publish the images. The following is one example of how this might appear.

I often receive inquiries through my private e-mail, asking if I could identify this insect or that spider, sometimes from other corners of the world besides the United States. This is always a welcome challenge, but the emphasis is usually on “challenge.” Not long ago, my friend Paul Kaufman sent me three wonderful images of a social wasp taken by Pablo Yoder, a missionary in Nicaragua. At least I recognized it as something in the family Vespidae, but there is a vast number of genera and species in the neotropics.

© Pablo Yoder

Thanks to Google image searches, I eventually pinpointed the wasp as the species Polybia emaciata. It is one of the few social vespid wasps that builds its nest of mud instead of paper. The more durable nature of the mud envelope allows the wasps to “hunker down” or flee when faced with a potential attack by a vertebrate predator. Contrast this behavior with the violent attacks launched by social wasps that build relatively flimsy nests of paper.

Enclosing a nest helps protect the eggs, larvae, and pupae that inhabit each cell in the horizontal layers of combs made by social wasps. Exposed combs are more vulnerable to predators and parasites since the adult wasps cannot be everywhere at once guarding each member of the brood.

© Pablo Yoder

So what is the wasp in two of these images doing with a big drop of water in its jaws? It is essentially bailing out the nest, keeping the mud from becoming saturated. It rains hard and often in the jungle. Even though the nests of wasps are usually ensconced beneath foliage in the rainforest canopy or understory, a good quantity of water still reaches those nests. The workers begin drinking the water, then walk to the edge of the nest and regurgitate droplets. The thick mud walls of the nests of this species take longer to become saturated than do paper nests of other species, but there is still cause for concern on the part of the nest inhabitants.

Nests of Polybia emaciata are typically inhabited by a small number of adult wasps. Colonies usually number between 100 and 500 wasps, while other species would have a much larger number. The nests vary in size from roughly nine centimeters to 22 centimeters in length, as least in one study in Panama (O’Donnell & Jeanne, 2002). The nests may also persist for several years due to their durability.

© Journal of Insect Science

O’Donnell and Jeanne elicited nest defense responses by tapping on the exterior of the nests, or blowing into the entrance hole. Most wasps would respond by rushing out of the nest and either attacking immediately or adopting an agonistic (warning) posture while perched on the exterior of the nest envelope. Not so with Polybia emaciata, which either flew away (though not abandoning the nest), or took refuge inside. Only sustained, escalated provocation resulted in the wasps exiting the nest, then pummeling and attempting to sting the researchers. Natural predators of tropical social wasps include birds, bats, and monkeys.

© Pablo Yoder

The diversity of wasps in the tropics, their survival strategies, and their relationships to other organisms is fascinating. I hope to one day see some of these remarkable insects for myself, but in the meantime I appreciate my readers sharing their own experiences and images.

Source: O’Donnell, Sean and Robert L. Jeanne. 2002. “The nest as fortress: defensive behavior of Polybia emaciata, a mud-nesting eusocial wasp,” J Insect Sci 2.3. 5 pp.

Wasp Wednesday: Polistes flavus

One of the most conspicuous wasps in the Sonoran Desert is the paper wasp Polistes flavus. This is a large wasp that frequents the same narrow belt as saguaro cacti, seldom being encountered at lower or higher elevations. Its large size, and almost entirely bright yellow color helps to separate this species from every other paper wasp in the region.

Little is known about P. flavus despite its relative, if seemingly localized, abundance. I have seen nests on only a handful of occasions, and they were all placed under the eaves of buildings. Unfortunately, those observations were made before I started taking digital images. I do recall that the nests were large, if only because the paper cells needed to accommodate these wasps have to be correspondingly large. Fortunately, my good friend Margarethe Brummermann did manage an image or two, one of which is shown below.

You are most likely to see these wasps in one of three situations: at water, at flowers, and perching on prominent vegetation. Worker females often congregate around receding waters of the intermittent streams characteristic of the Sonoran Desert. They may even land on the water, sprawling across the surface film and drinking deeply. They will visit swimming pools when natural sources are not available. Many other species of desert Polistes and Mischocyttarus will exhibit the same behavior. They all need water to manufacture saliva to mix with wood fibers to create the paper used in building their nests.

Paper wasps attack caterpillars and other insects to take back to the nest to feed the growing larvae, but the adult wasps need carbs, not protein. Consequently, paper wasps make use of flower nectar and “honeydew” from aphid colonies. Look for Polistes flavus on the blossoms of Seep Willow (Baccharis salicifolia) and, to a lesser degree, Desert Broom (Baccharis sarothroides). The wasp in the image below is on a Seep Willow.

Male paper wasps are often even larger than the females and therefore even more obvious and intimidating. This is especially true when they engage in territorial behavior, perching on prominent twigs or branches along the edges of dry riverbeds and other flyways. From these outposts the males scan for passing females and rival males. They will also chase away other insects, then return to their perch or another perch close by. Males do not have stingers, but are powerful enough to back up their threats.

How do you tell a male paper wasp from a female? Males have longer antennae, dramatically hooked at the tip, and their faces are more “square” than those of females. Males tend to have very pale faces, too. Females have shorter antennae, not as prominently hooked, and triangular faces that are usually darker.

One paper wasp likely to be confused with P. flavus is P. apachus, which is colored in yellow and reddish brown. P. apachus almost invariably has two parallel yellow stripes on the top of the thorax (see below), whereas that area is almost entirely yellow in P. flavus. Another confusing species is P. aurifer, which is entirely reddish brown on top of the thorax.

Look for P. flavus in Arizona, as well as southern California, Nevada, Utah, New Mexico, and western Texas. Males can easily overwinter in milder parts of that range, though they are normally more common in autumn as colonies prepare to suspend activities for the colder months.

Wasp Wednesday: Western Paper Wasp

Here in central Colorado we are experiencing higher-than-normal autumn temperatures. Several record highs were broken Monday, October 24, 2011 in fact. The warmth has meant that most of the social wasps are still active. Among the most common of those is the Western Paper Wasp, Mischocyttarus flavitarsis. This insect can easily be mistaken for a species of Polistes, but Mischocyttarus has a petiolate (stalked) abdomen in contrast to the more sessile abdomen of Polistes.

Mischocyttarus is a genus of roughly 260 species that is most diverse in the neotropics of Central and South America. Their classification has presented something of a nightmare to entomologists and it seems the end is nowhere in sight. Currently, there are three recognized species that make into the United States and southwest Canada, all in the subgenus Phi. Here in the western U.S., only M. flavitarsis occurs, but it ranges from British Columbia to Mexico, east to Nebraska and west Texas. I have encountered the subspecies M. f. navajo in Arizona (see image below), which is also found in Mexico.

This genus constructs small, uncovered paper combs essentially identical to the nests of Polistes paper wasps. My personal observations of M. flavitarsis flavitarsis in Portland, Oregon have demonstrated that the wasps prefer to nest in cavities. This may be in response to the rainy climate there, and/or offer greater protection from birds. Avian predation is a chief mortality factor for larvae and pupae of other species in the genus (Hermann & Chao, 1984). Certainly, nests I have found elsewhere have been more exposed, such as the M. mexicanus mexicanus nest imaged below at Resaca de la Palma State Park near Brownsville, Texas.

Like other paper wasps, Mischocyttarus females prey primarily on caterpillars to take back to the nest and feed their larval siblings. A study of M. flavitarsis demonstrated that the wasps rely mostly on olfactory cues for detecting prey. They may home in on volatile chemicals secreted by plants in the wake of damage from caterpillars, and especially the odor of the droppings or “frass” left behind by feeding caterpillars (McPheron & Mills, 2007).

The adult wasps themselves frequently seek out colonies of aphids to sip the sugary “honeydew” secreted as a waste product by the aphids. You may find an abundance of wasps, flies, and other insects around deciduous trees, and even pine trees that are infested with aphids.

Male behavior is geared to finding mates. A study of M. flavitarsis navajo in Arizona revealed that in late summer, males “patrol” areas frequented by females. Riparian corridors are a typical location for this activity. Each male will stop frequently to scent-mark twigs, foliage, and other objects with a chemical secreted by his abdomen. The male vigorously defends his marked patches from competing males.

Males that emerge in the fall form leks near potential hibernation sites. A lek is a stage where males congregate to show off to females. In this instance, each male simply scent-marks a perimeter roughly ten centimeters in diameter and sticks to this territory. Incoming females are free to choose (or reject) any male without interference from other males.

At this time of year, females of Mischocyttarus are seeking places to hibernate. Males may seek shelter as well, but they are unlikely to survive until the following spring. The females may spend the colder months under rocks, logs, under loose bark on trees, in the attics of homes, or other protected niches. They can congregate peacefully with others of their kind, and even with Polistes paper wasps. Warm winter days may find the wasps emerging to bask and explore their immediate surroundings.

Mischocyttarus is one of many social wasps that can be observed even at fairly close range without interfering with their behavior or eliciting an attack response. Take time to get to know them. You might learn something that nobody else has yet seen.

Sources: Hermann, Henry R. and Jung-Tai Chao. 1984. “Nesting biology and defensive behavior of Mischocyttarus (Monocyttarus) mexicanus cubicula (Vespidae, Polistinae),” Psyche 91: 51-66.
McPheron, Linda J. and Nick J. Mills. 2007. “Influence of visual and olfactory cues on the foraging behavior of the paper wasp Mischocyttarus flavitarsis (Hymenoptera: Vespidae),” Entomol Gener 30(2): 105-118.
Preston-Mafham, Rod and Ken. 1993. The Encyclopedia of Land Invertebrate Behavior. Cambridge, Massachusetts: The MIT Press. 320 pp.
Silveira, Orlando Tobias. 2008. “Phylogeny of wasps of the genus Mischocyttarus de Saussure (Hymenoptera, Vespidae, Polistinae),” Rev. Bras. Entomol. 52(4).

Wasp Wednesday: Western Yellowjacket

Notorious. That describes the Western Yellowjacket, Vespula pensylvanica (and yes, the species name is spelled correctly). I recall this social wasp from my childhood in Portland, Oregon where it was a constant presence at picnics, barbecues, and garbage cans at the zoo and every other urban park. Here in Colorado Springs they are equally pestiferous, and persist deep into the fall.

Each year, the Western Yellowjacket colony cycle begins with queens searching for nesting sites. These females are larger, and more yellow in color than the worker caste. They typically emerge from their winter hibernacula sometime between March and April, though it may take awhile for a queen to find a suitable subterranean niche where she can start building her nest. I imaged the queen below at the Cheyenne Mountain Zoo on July 9, 2011, so she still had no help from workers in constructing her nest.

Once the queen’s worker offspring can contribute, the colony and nest quickly expand in size. Mature nests, based on records from Pullman, Washington and La Grande, Oregon, can exceed a population of 2,000 workers (average about 1,800) and contain 4,000 cells or more in the paper combs.

Nests are usually located in abandoned rodent burrows ten to fifteen centimeters below the surface of the soil, with entrance tunnels ten to thirty centimeters long. There is often a mud turret surrounding the entrance hole. Look for yellowjackets coming and going from the same spot to locate a nest entrance. You can approach closely to watch their activity without arousing the occupants, but run a lawnmower over the nest and watch out! One of my elementary school science teachers told me he once drove a stake right through a nest. That could not have been a pleasant experience.

Western Yellowjackets are best known for their aggressive scavenging behavior. They have to secure large quantities of protein to feed the larvae in the nest, and the workers take that job seriously. It is much easier to haul away a chunk of your tuna sandwich, chicken leg, or burger than it is to go kill a series of small insects. Still, this species does its fair share of scavenging road kill and preying on true bugs, spiders, flies, grasshoppers, even slugs.

The adult wasps need carbohydrates to fuel their active lifestyle, so that is why they crawl into your soda can. Normally, in nature, they prefer the sweet waste products secreted by aphids and scale insects. This “honeydew” is like the Nectar of the Gods to social wasps. Last week I imaged several workers lapping up the honeydew of Cinara conifer aphids on a pine tree at the Cheyenne Mountain Zoo.

The last chapter in the annual colony life cycle is the production of new queens and males. These reproductives are liberated at the end of the season and they fly out to find mates from other colonies. The males, with their long abdomens and antennae, seem to congregate around the tops of small trees where they perch to await passing females. The males may dislodge each other from prime lookout posts, but they don’t have stingers and such squabbles are therefore not life-threatening.

Western Yellowjackets can be “bad” some years, with much higher than normal population densities. This usually occurs when a warm, dry spring season allows queens to get a head start on establishing colonies. The result can be worker wasps wreaking havoc on fruit tree orchards, logging camps, and outdoor recreation destinations later in the summer.

The Western Yellowjacket is exactly that: a western North American species ranging from southern British Columbia, Alberta and Saskatchewan south through the Pacific coast and Rocky Mountain States, all the way to Arizona and New Mexico at higher elevations. There are scattered records across the northern Midwest as far east as Michigan; and this species has been introduced to Hawaii as well.

Source:Akre, Roger D., Albert Greene, et al. 1981. The Yellowjackets of America North of Mexico. Washington, DC: USDA Agriculture Handbook Number 552. 102 pp.

Wasp Wednesday: Northern Paper Wasp

When I lived in Cincinnati, Ohio I found the Northern Paper Wasp, Polistes fuscatus, to be among the most abundant of the social wasps. This has changed recently as the European Paper Wasp, Polistes dominula, has overtaken its native counterpart to become the dominant wasp, especially in urban areas. Still, most people living in the eastern United States and adjacent southern Canada are familiar with P. fuscatus.

Paper wasps belong to the same family as yellowjackets, true hornets, and potter and mason wasps: Vespidae. Whereas the yellowjackets tend to be wasps of northern North America, most diverse in boreal regions and cooler habitats, paper wasps are decidedly tropical, with only a handful of species ranging north into the U.S., and fewer still reaching Canada.

Paper wasp colonies are on the small side, rarely exceeding about 200 individual wasps. They build unprotected paper combs they suspend from twigs, stems, the eaves of homes, and other semi-protected locations. The stalk (pedicel) from which the nest hangs is sturdy and often coated with a dark substance that repels ants, the chief threat to the larvae and pupae inside the cells of the comb.

In North America, the life cycle of the nest begins when overwintering female wasps emerge from torpor and begin construction of nests. There is no apparent “worker” or “queen” caste in paper wasps, but recent studies have revealed that in fact some females are destined to become “gynes,” the reproductive females. Others will become subordinates to gynes. This is likely determined in their larval stage. More than one gyne may act as the “foundress” of a nest, but one individual eventually asserts her dominance, and the subordinate wasp leaves.

The gyne performs all roles as the nest founder, building the nest as well as securing food for her developing larval offspring. She makes the nest by harvesting fibers from wood surfaces, be it dead trees, dead woody stems, or fence posts. The fibers she scrapes she then chews into a saliva-soaked ball of pulp. Back at the nest she deftly plies the pulp into a strip of paper added to the existing comb.

Paper wasps are well worth having in the garden. They prey heavily on other insects, especially caterpillars. The Northern Paper Wasp has even been observed entering the silken tents of Fall Webworms to grab the hairy caterpillars. The wasp butchers her kill on the spot, stripping off any irritating hairs or spines that could not be easily consumed by the larvae back in the nest.

Once back at the nest, the wasp either feeds the larvae directly, or shares parts of the “meatball” with fellow workers that in turn distribute the food to the larvae. One larva occupies each hexagonal paper cell. Once the larva reaches maturity, it spins a silken dome over the top of the cell and then molts to the pupa stage. Shortly thereafter, an adult wasp chews its way out of the cap to freedom.

Late in summer, or in early autumn, the colony produces males. The male’s sole function is to fertilize the next generation of gynes. Watch a colony in August or September and see if you can tell the males from the females. It is actually pretty easy:

• Males have long antennae, usually curled at the tips (females have shorter, straight antennae, though both genders have an “elbow” in each antenna)
• Males have square, yellow faces (females have dark, triangular faces)
• Males have a blunt tip to the abdomen (the abdomen of females tapers to a point)

Males and females both are abundant on flowers of goldenrods (Solidago) and throughworts (Eupatorium) at this time of year. With so many wasps easily visible at the same time, it becomes evident that the Northern Paper Wasp exhibits an extreme degree of variability in color and pattern. Most specimens will have a pair of large, deep red blotches on the second abdominal segment, but the yellow markings vary considerably.

Recent DNA analysis is adding mud to the situation instead of clarifying it, but chances are that the western “species” Polistes aurifer, shown below, is going to be lumped back in with Polistes fuscatus.

Enjoy watching these wasps. Their season is short, and unless you antagonize the ones on a nest (and they will give a threat display by standing on tip-toe and raising their wings), they make perfectly peaceful neighbors.