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  Adult paper wasps can be anesthetized with ether, and then marked for individual recognition. I use a color code of paint-pen dots on the thorax.

(Left) I then introduce the marked wasps into their own nest, or into foreign nests if they are less than 24 h old. (Right) Note the marked Polybia worker among her adopted nest mates.

(Photograph by Larry Gilbert, U. Texas-Austin) Yes, I do get stung. This particularly unsavory bout of pain was courtesy of Polistes erythrocephalus in Corcovado N.P., Costa Rica. I "collected" the entire colony the following day.

I. Independent-founding wasps. These species initiate new nests as lone females, who may later be joined by cofoundresses. They are characterized by simple nest architecture, nearly always consisting of an open brood comb suspended from a simple stalk or pedicel. Colony sizes are typically small- on the order of several dozen adults.

P. instabilis (Guanacaste, Costa Rica). A pair of cofoundresses at a new nest. In this population, individuals exhibit marked social flexibility, often moving among several new nests and the older parent nest during colony establishment.

Unidentified Mischocyttarus (Tiputini, Ecuador). This group of adults barely fits on their tiny nest, which hasn't produced adults yet, under an orchid leaf. This may be a colony that re-nested after their mature nest was destroyed.

Unidentified Mischocyttarus (Guanacaste, Costa Rica). Adult females on independent-founding wasp colonies often engage in aggressive dominance interactions; here, an older female with pale eyes bites a younger one with dark eyes (indicated by red arrow). Dominance status often corresponds with reproductive potential and with task performance: dominant females are more likely to lay eggs, and less likely to perform risky tasks such as foraging.

The quintessential independent-founding wasp, subject of many studies of behavior and physiology. 

P. instabilis (Guanacaste, Costa Rica). Two post-emergence colonies that have produced offspring worker females. Brood are clearly visible in the nest cells. The capped cells are in the pupal stage.

P. carnifex (Guanacaste, Costa Rica). Here, females divide a load of caterpillar flesh that was brough t to the nest by a forager.

Polistes atterimus (Monteverde, Costa Rica): Newly founded (left) and post-emergence (right) nests. This large, slow-tempo species is widespread at montane elevations in Costa Rica. They are probably mimics of Synoeca septentrionalis.

  M. tomentosus (northeastern Peru). Some species in this genus suspend their nest combs from very elongated petioles (indicated by red arrow). The wasps apply an ant repellent secretion to the petiole.

Unidentified Mischocyttarus (Tiputini, Ecuador). This lone foundress cheated to increase her nest's effective petiole length, by nesting at the end of a splinter on a palm trunk wall.

Unidentified Mischocyttarus (Tiputini, Ecuador). Most species in this genus have small colonies, and the wasps are not aggressive in defense of their nests. Many are timid. They appear to rely on crypsis to hide their nests from predators, often nesting in sheltered, dark locations. This colony give one of the most amazing examples of nest crypsis I have ever seen. The nest was built exposed on the pillar of a porch roof. The cell openings faced in toward the substrate, and the back of the nest (left photo) was covered with lichens and mold. In side view (right photo), the ruse becomes apparent.

Mischocyttarus immarginatus (Guanacaste, Costa Rica). This handsome species often nests in close association with Polybia wasps.

M. mixtus (Monteverde, Costa Rica).This species often constructs cryptic, elongated nests at Monteverde.

M. atrocyaneus (Monteverde, Costa Rica). Like many, if not most, of its congeners, this species mimics a more aggressive eusocial wasp. In this case the model is the venom-spraying Parachartergus fraternus (or the closely similar P. apicalis).

M. mastigophorus (Monteverde, Costa Rica). This species has been an important research subject for me. I have focused on color polymorphism (next photos) with Dr. Frank Joyce, and behavioral and physiological implications of dominance interactions.

M. mastigophorus (Monteverde, Costa Rica). A M. mastigophorus queen accruing some direct fitness- her gaster is inside a cell, as she lays an agg. This cell recently held a pupa.

M. mastigophorus females in left photo, males in right photo (Monteverde, Costa Rica). Here the two discrete color forms that occur at Monteverde are shown. In each photo, the two wasps are nest mates.

M. mastigophorus females with Agelaia xanthopus (left photo) and A. yepocapa (right photo); in both cases, the M. mastigophorus is on the left. Many, perhaps most, species of Mischocyttarus mimic other eusocial wasps. We believe that the two color forms are mimics of different species of Agelaia wasps, which also occur at Monteverde, and are more abundant and aggressive than M. mastigophorus.

M. mexicanus (Monteverde, Costa Rica). Brood are clearly visible in the nest cells. Note the katydid roosting nearby.

  M. pallidipectus (Monteverde, Costa Rica). This large aggregation persisted on a sheltered electric meter for several days.

II. Swarm-founding wasps. Swarm-founders initiate newnests in coordinated groups of queens (reproductive females) and workers. Nest architecture is variable bur more complex than independent-founders' nests; swarm-founders' nests often include a covering envelope. They are largely restricted to the Neotropics, though a few species range into the subtropics.

Metapolybia azteca (Guanacaste, Costa Rica). Here is a newly arrived swarm. Note the start of nest comb construction at the center; the covering envelope will be added later. The arrival of a coordinated swarm allows foraging for nest materials to coincide with guarding against ants and other natural enemies.

Groups of swarming wasps often cluster along the swarm route, as seen in these Polybia raui.

Mischocyttarus immarginatus (nest indicated by red arrow in left photo) nesting with Polybia occidentalis (Guanacaste, Costa Rica). Presumably because of their large colonies and effective colony defense, swarm-founders often attract nesting associates.

Most species nest inside cavities.

  A. panamaensis (Monteverde, Costa Rica). Some species of Agelaia attain very large colony sizes; these are combs from a nest I collected with Jim Hunt in the San Luis Valley below Monteverde, Costa Rica. This nest was in a typical location: a large cavity inside a fallen tree trunk, near ground level.

  A. panamaensis (Monteverde, Costa Rica). A small fraction of the adult wasps from the colony above are in the sheet; molecular biologist cum wasp ecologist Neal Chernoff is smiling because he did not participate in collecting this colony.

A. panamaensis (Monteverde, Costa Rica). One reason that Agelaia can attain large colony sizes may be their necrophagous habits. Foragers collect flesh from vertebrate and large invertebrate carcasses, as the forager on a chicken bait is doing at left, then presumably these are brought to their colonies (right photo) and fed to the developing brood. 

A. cajennensis (Corcovado N.P., Costa Rica). This Agelaia species often has smaller colonies, and nests in restricted spaces. Here is a colony that nested inside a T-shirt hanging on a clothesline.

A. areata (Bijagua, Costa Rica). This species is unusual in the genus because it costructs envelope-covered nests that are not inside cavities.

A. pallens (left: northeastern Peru; right: Tiputini, Ecuador). Like their sister genus Agelaia, Angiopolybia foragers are highly necrophagous. This species is common nesting in the understory of wet forests in the Amazon basin. Nest are often built under broad leaves.

A. pallens (Left-Corcovado N.P., Costa Rica; Right- Bijagua, Costa Rica). Wasps in this genus are unique in the Neotropics because they are nocturnal. In the day, the workers cluster on the nest surface, effectively forming an envelope over the brood with their bodies.

B. mellifica (Guanacaste, Costa Rica). Colony sizes vary widely in this genus; this common species often achieves adult populations in the tens of thousands in a nest. They are very aggressive, and possess barbed stings similar to honey bees. 

  Unidentified Brachygastra (Yasuni N.P., Ecuador). This small-colony species applies an unidentified white substance to the nest exterior. This whitewashing may help conceal the nest when viewed from below, against the sky or backlighting.

Unidentified Chartergellus (Yasuni N.P., Ecuador). The red arrow indicates the cryptic nest against a huge tree trunk. There is also a Metapolybia nest visible lower on the trunk. When I attempted to collect some adults, the colony failed to respond to disturbance (tapping with an insect net) at first, then rapidly mounted a mass attack.

Charterginus fulvus (Yasuni N.P., Ecuador). This species was common nesting near the ground in wet forest understory. The hexagonal nests house small colonies. Note that, like the small-colony Brachygastra above, these wasps paint their nests with white substance.

  Charterginus fulvus (Tiputini, Ecuador). Note the odd shape of the nest in profile, and the application of white "paint".

E. nigra (Monteverde, Costa Rica). This species builds nests of very strong, felt-like paper high in trees. Note that birds (probably wrens) have nested near the nest, presumably gaining protection from predators.

Unidentified Leipomeles (Yasuni N.P., Ecuador). This and the following nest were apparently built by the same species. The nests are on the undersides of large leaves in the wet forest understory. Note how the wasps have added pigment to the translucent nest paper, roughly mimicking leaf veins.

  Unidentified Leipomeles (Yasuni N.P., Ecuador). This remarkable nest shows modification of the nest envelope paper to closely match veins of the substrate leaf (nest indicated by red arrow). They also coat the petiole of their nest leaf with a sticky substance which presumably repels ants.

Unidentified Metapolybia (Gamboa, Panama). Nests of these wasps can be very cryptic, aided by the fact that the workers apply lichen and other materials to the nest paper. Two nests on a tree trunk are indicated by the red arrows.

  M. azteca (Guanacaste, Costa Rica). Some species also place transparent windows of salivary secretion in the paper of their nest envelopes; a series of these windows is indicated by the red arrow (left photo).

Nectarinella championi (Bosque Caliente hot springs, Guanacaste, Costa Rica). Nests of this species are often built on large tree trunks, and can be very cryptic. This species seems to have an unusual geographic distribution in Costa Rica, sometimes being common at middle elevations.

Nectarinella championi (Bosque Caliente hot springs, Guanacaste, Costa Rica). This species gets my vote for cutest paper wasp. Look closely around the nest entrance, and you can see (yet another) amazing adaptation to reduce ant predation: the paper and substrate are covered with a fuzz of sticky traps that the wasps have built.

  P. fraternus (Guanacaste, Costa Rica). This aggressive species pursues human intruders for hundreds of meters from the nest, and can spray venom into faces. The nest paper is white and contrasts with the black-bodied wasps. The wasps have white wing tips, and are mimicked by several other species of insects, including some species of Mischocyttarus wasps. The nest envelope is beautifully sculpted; the wasps build across (perpendicular to) the ridges in the paper (indicated by red arrow in right photo).

P. smithii (All-northeastern Peru). This very cryptic nest was built on a piece of roofing thatch, and coated with lichens. In contrast to P. fraternus, the wasps were very docile.

  P. occidentalis (Both-Guanacaste, Costa Rica). Another important research subject for my lab. Colony sizes are often close to a few hundred workers. Marked workers are shown in the left photo. In the right photo, a worker dumps water from the nest following a rain shower.

P. aequatorialis (Both-Monteverde, Costa Rica). A high-elevation species, similar in many ways to P. occidentalis but with larger typical colony sizes of several thousand adults. The nest envelopes have multiple layers and many air pockets, perhaps as an adaptation to cool temperatures; I don't know what function (if any) the long paper tabs possess. The colonies store large amounts of concentrated nectar (like honey). I used RAPD genetic markers to demonstrate genotypic effects on task specialization by workers.

P. aequatorialis (All-Monteverde, Costa Rica). Left-A building worker adds moistened wood pulp to the nest. Middle-A marked forager gives nectar to a nest mate. Right-A biting interaction. Biting appears to induce and maintain foraging in recipients.

P. sericea (Hato Masaguaral, Venezuela). Some Polybia species build large nests and live in large colonies.

P. emaciata (Left-Gamboa, Panama; Middle and Right-Bijagua, Costa Rica). Mud-nesting has evolved from paper-nesting in a few Polybia species.

P. raui (Gamboa, Panama). Here workers exhibit a putative defensive signal upon nest disturbance, which is called gaster-flagging.

P. raui (Monteverde, Costa Rica). This species' nest paper is typically ruddy in color and very brittle. In Monteverde, they typically suspend the nest from rootlets in land slides and road banks.

Unidentified Polybia species (Monteverde, Costa Rica).

  P. exigua (Hato Masaguaral, Venezuela). This small-bodied species was common in the Venezuelan llanos; nests often incorporated leaves into the paper.

S. septentrionalis (Left-Corcovado N.P., Costa Rica; Right-Monteverde, Costa Rica). These wasps are infamous for their painful stings and ferocious colony defense. When mildly disturbed, they produce an ominous rushing sound, with synchronous rhythm, by rubbing against their corrugated nest paper. Watch out.

  Unidentified Microstigmus (Las Cruces Biological Station, Costa Rica). This species is being examined by Dr. Bob Matthews. It nested under large melastome leaves at the Wilson Botanical Gardens, and the nest bag was constructed from leaf hairs scraped off nearby veins by the wasps.