Cradling a fresh ball of mud, this pretty female potter wasp gets ready to put finishing touches on clay pots provisioned with caterpillars for her developing youngsters.
Green and brown caterpillars and a legless wasp larva filled the pot of a potter wasp discovered in my garden in Columbia, Maryland.
This week we return to Borneo and to a lodge on the banks of the Kinabatangan River where a vendor set up a small table of their wares. Amongst the colorful trinkets, a large potter wasp decided to set up shop and build a series of clay pots which would be the nurseries for her offspring. Nests are often built on sunny exposed structures such as on tree trunks, rocks, or buildings, but in this case a somewhat shaded display table worked just fine. After finding just the right blend of muddy clay soil near the riverbank, the female wasp gathers it into a ball and transports it to the nest site. Using mouthparts and legs, the clay is molded into to an oblong pot cemented to the underlying substrate.
While the pot is still unsealed, mom lays an egg inside the pot, attached to the clay by a silken strand. She then goes into the forest to hunt caterpillars, the larvae of moths and butterflies. Hapless caterpillars are stung and paralyzed but not killed by the venom. Immobilized and defenseless, the caterpillars become a stable source of fresh meat for the developing wasp larva. Once captured by the wasp, the hapless caterpillars are carried back to her nest and stuffed into the pot. Often several different species of caterpillars will be used as a food source. In one study the number of caterpillars found in each chamber ranged from 4 to 9.
This small table of trinkets holds a surprise, the nest of a potter wasp. Watch as she crafts a clay pot and then flies off to find a caterpillar that will serve as food for her young. She stings the caterpillar with paralytic venom and stuffs it into the pot which already contains her egg. The caterpillar is fresh meat for her spawn. The pot is sealed with a glob of mud and after a drink of water, off she goes to hunt for mud and caterpillars to start the next pot.
What wonders lie within this diminutive piece of earthenware adorning a rock wall in my garden?
With sufficient food available for her baby to develop, the pot is sealed with another glob of mud and construction of the next pot begins. Each pot in the nest requires no more than a day to build and provision. Individual pots are added to existing ones and some potter wasp condos may consist of more than 20 individual chambers with growing wasp larvae inside. The entire multi-pot construct is then sealed with a layer of mud to help thwart predators and parasitoids intent on making a meal of paralyzed caterpillars and developing wasp larvae.
Potter wasps eat nectar and pollen when not throwing pots.
This Bornean potter wasp is part of a large widely distributed clan of more than 3,000 wasps known as the Eumeninae. In a previous episode, we met pretty potter wasps in the genus Ancistrocerus in Maryland where we commonly see adults feeding on the nectar and pollen of goldenrods in autumn.
Acknowledgements
The informative article “Nesting Behaviour of Potter Wasp, Delta pyriforme (Fabricius) (Hymenoptera: Eumeninae) from the Koradi Region, Dist, Nagpur, Maharashtra” by Chanchal R. Deshmukh was consulted to prepare this article. Thanks to Dan, Kristie, Bob, Pat, and Paula for helping spot and study potter wasps in Borneo.
One look at this beautiful Batocera beetle makes it easy to understand why they are called longhorn beetles.
Once again, we return to the rainforests of Borneo where in previous episodes we met marvelous millipedes, fierce terrestrial and arboreal ants, and gorgeous lanternflies. This week we meet some of the largest beetles on the planet, longhorn beetles. One look at these supersized insects reveals exactly why they are called longhorn beetles. These beauties have antennae that often exceed the entire length of their body. Despite what some may think, touch is but one of the functions of antennae for insects. In addition to picking up tactile vibrations, antennae are usually festooned with a vast array of chemoreceptors used to detect everything from something good to eat, to where the party is, to who might be the love of their life. Longhorn beetles like the ones you see here can communicate with other members of their species using airborne chemicals called pheromones over distances of hundreds of yards.
One would think that these large beetles would be a prime target for predators like birds and lizards hankering for a tasty high protein meal. Fortunately, these beetles and many other species of insects have a clever trick up their sleeve, or better said, between two thoracic segments of their body. Just behind the beetle’s head on the first segment of the thorax, a small sharp ridge of exoskeleton called the scraper runs transversely across the undersurface surface of the segment. On the segment just behind the first, the exoskeleton bears a patch of tiny regularly spaced ridges and grooves. As the beetle flexes and relaxes these body segments, the scraper moves over the patch of groves, producing a clearly audible sound. These acoustic vibrations, called stridulation, are found in many species of insects and are used to attract mates, defend territories, or as a defense to startle predators. In the case of our very large and beautiful longhorn beetles, when captured they flexed their body up and down, producing an annoying and surprisingly load squeaking sound, not quite fingernails on a chalkboard but close to it.
Borneo has lots of big beautiful longhorn beetles with a cool trick to ward off predators. Listen as this Batocera beetle produces a squeaky sound by rubbing two body segments together. A hard scraper on one segment of its thorax moves across a series of tiny groves and ridges on the segment just behind the first to produce acoustic vibrations called stridulation. We found a huge tooth-necked beetle in a bathroom one morning. This giant really amped up the squeaky alarm when harassed by a human. After scaring and entertaining the humans, upon release, it scampered up a nearby palm tree.
Someone left the light on in the bathroom and someone else had a big surprise when they walked into the bathroom the next morning. Longhorn beetles are really big in Borneo. Credit: P. M. Shrewsbury, UMD
We were fortunate to discover a spectacular toothed-neck longhorn in a bathroom one morning where it was attracted to the lavatory by a light left on overnight. When grabbed by a human, this giant really amped up its stridulatory vibrations. Loud squeaks coupled with flailing legs and spiny body armor made this beetle hard to handle even for a bug geek. One can only imagine the surprise a small barbet gets when it snares a large longhorn beetle and encounters thrashing legs, snapping jaws, and brain-rattling vibrations from its intended meal.
Acknowledgements
Bug of the Week thanks Dan for wrangling the large tooth-necked beetle for this episode and Paula for sharing her images. Kristie, Bob, and Pat provided sterling commentary on stridulation and its importance to longhorn beetles. Two informative references, “Cerambycid Beetle Species with Similar Pheromones are Segregated by Phenology and Minor Pheromone Components” by Robert F. Mitchell, Peter F. Reagel, Joseph C. H. Wong, Linnea R. Meier, Weliton D. Silva, Judith Mongold-Diers, Jocelyn G. Millar, and Lawrence Hanks, and “Stridulatory Apparatus and Analysis of the Acoustics of Four Species of the Subfamily Lamiinae (Coleoptera: Cerambycidae) by Warrren E. Finn, Victor C. Mastro, and Thomas L. Payne, provided insights into stridulation and mating behaviors of longhorn beetles.
With sharp jaws ready, workers prepare to defend the colony from nosy bug geeks. Image: P. M. Shrewsbury, UMD
In recent episodes we visited traveled to Borneo to visit recycling millipedes, beautiful lanternflies, fierce rainforest ants, and one of the largest ant species on our planet. This week we island hop and make two stops. First stop is Lizard Island just off the coast of Australia on the Great Barrier Reef. Second stop is a return to the rainforests of Borneo. A few years ago, a study abroad landed Bug of the Week on Lizard Island. While bumbling through the underbrush in search of spiders, I bumped into a small tree bearing several football-sized clusters of glossy leaves. I was surprised and delighted when scores of beautiful green ants issued forth from one leaf-cluster and set to work defending their redoubt by dropping on my arm and attacking. Fortunately, the furious soldiers lacked stingers and their bite was mildly unpleasant at worst. Their attack left the air laced with the odor of formic acid released from specialized poison glands as a defense.
Food gathered on the ground will be carried along roots and up into the treetop where nests are built. When nosy humans get a little too close, workers guarding the nest are on high alert, ready to attack.
A pair of workers exchange some information and maybe some food.
Green tree ants and other weaver ants represent a unique branch of the ant’s evolutionary tree. While other more familiar ants build colonies in soil or decaying wood, weaver ants live the life arboreal and construct clever nests in the canopies of trees. Nest building begins when one or more large workers known as majors grasp the margin of a leaf and fold it over or hold it in close proximity to an adjacent leaf. Other majors soon join the effort and, in a fascinating display of cooperation, they stand shoulder to shoulder to pull the leaf margins into close approximation to each other. When the gap narrows the workers stand in place, hold the leaf fast, and await the next step in the nest making process. Other workers gather ant larvae from deep within the colony. These youngsters are approaching their time of pupation, a time when they produce silk, and in their heads are fully functional silk glands. The workers gather several of these larvae and carry them to the construction site where leaf-grasping workers await their arrival. Using the silk-spinning larvae as living bobbins, workers move the larvae back and forth, weaving silk across the gap, firmly stitching the leaves together. This process is repeated time and again with other nearby leaves until the nest is complete.
Some ants, including green tree ants, conduct a remarkable behavior called social carrying where one ant picks up and transports another. This may be a way to get more workers to an important project pronto. Video at about half speed.
A single colony of green tree ants may consist of several smaller nests distributed in several trees. P. M. Shrewsbury, UMD
Green tree ants build multiple nests throughout the tree’s canopy and several trees may be enlisted to house a single colony. In one of these individual nests resides the glorious queen whose task it is to eat meals of protein and carbohydrates brought to her by the workers. These rich nutrients are turned into thousands of eggs. Since workers large and small, young and old, share the same mother, the queen, they are all sisters and the building, care, and defense of the colony truly is a remarkable act of sisterly cooperation. The size of some weaver ant colonies has been estimated to exceed more than 500,000 workers. Like many of their kin, green tree ants are omnivores, consuming other insects they capture and gathering carbohydrates in the form of honeydew excreted by legions of arboreal sucking insects such as scale insects, aphids, and spotted lantern flies we met in previous episodes.
I had a golden chance to witness another extraordinary feat of cooperation in the rainforest of Borneo one evening when weaver ants discovered and captured an enormous scarab beetle. This colossal meal was easily a hundredfold more massive than the weight of a single ant. The problem: How do ants bring this banquet back to the nest to feed the queen and brood? The answer: Sisterly cooperation! As you watch the video, witness scores of worker ants transporting the huge beetle along a wooden rail adjoining a walkway. After encountering a vertical fencepost, ants use sister power to levitate the beetle up and over the post. On the other side of the post a short hike brings them to a leafy bridge that serves as a causeway to their arboreal nest. On the way home as night falls, the crotch between two leaves becomes an insoluble obstacle and the beetle becomes trapped. At sunrise the next morning, the beetle was gone and a solitary worker was stationed at the portal where the leafy trail home met the walkway. Was the beetle dismembered and carried piece by piece back to the nest? Did the sisters lose their grip and drop their prize? Was there an alternate and more passible route back to the nest? Only the weavers know.
Scores of worker ants transport a huge scarab beetle along a wooden rail adjoining a walkway. After encountering a vertical fencepost, ants cooperate and use sister power to levitate the beetle up and over the post. On the other side of the post a short hike brings them to a leafy bridge that serves as a causeway to their arboreal nest. On the way home as night falls, the crotch between two leaves becomes an insurmountable obstacle and the beetle becomes trapped. At sunrise the next morning, the beetle was gone and a solitary worker stationed at the portal guarded the leafy trail from the walkway back to the nest. Video at twice life speed.
Well, green tree ants prove they can cooperate with other members of the family, but how about with other species of creatures, maybe even with humans? The value of weaver ants in pillaging plant-eating insects was recognized nearly 1,800 years ago by citrus growers in China. Ancient writings show that nests of weaver ants were regularly transported and installed in orchards where ravenous workers converted citrus-eating pests into food for the colony and queen. These clever orchardists are credited with one of the earliest records of a practice still widely used in crop protections today called biological control. Maybe humans can learn something about the value of cooperation by taking some time to watch ants.
Acknowledgements
Bug of the Week thanks Dr. Shrewsbury for providing photographs used in this episode and the students and faculty of BSCI 279A, Natural History, Ecology, and Geology of Australia, for providing the inspiration for this story. The spectacular reference “The Ants” by Bert Hölldobler and Edward O. Wilson provided the information used to prepare this episode. We thank Dan for discovering the large scarab beetle seen in this episode, the eagle-eyes of Kristie, Bob, and Pat for spotting insects and Paula for sharing images used in this episode.
Night time is the right time to observe and enjoy Malaysian giant forest ants in Borneo.
This week we say goodbye to periodical cicadas and return to the rainforests of Borneo where we last visited rapacious Leptogenys ants, rainforest raiders, as they pillaged other small animals on the rainforest floor. This week we venture into the forest to meet one of the largest species of ants on the planet, the Malaysian giant rainforest ant.
To witness these giants of the ant world, a flashlight and willingness to venture into the forest at night provide your best bet for encountering these behemoths of the ant world. Unlike some species of ants that can readily be found during the daytime, giant ants conduct most of their food gathering at night. Scientists have discovered that shortly after dusk scores to thousands of foragers leave one or more subterranean nests that comprise a colony, move across the forest floor, and invade the forest canopy. High in the treetops, honeydew produced by sucking insects including planthoppers, treehoppers, and lanternflies constitutes about 90% of what foragers collect to bring back to the nests. The remaining sources of food gathered by workers include small insects and nutrient rich bird droppings. Why forage at night rather than during the day? Night time foraging in the forest canopy may have to do with avoidance of predators and parasitoids. Birds and wasps that rely on sight to find prey may be more active and efficient in trees during daylight hours. Also, several other species of ants living in the same habitats are highly active and dominate foraging trails and resources during daylight hours. High levels of interspecific ant traffic and food raids in the canopy may displace giant tree ants and limit their activities to the night.
Amidst the music of the rain forest at night, Malaysian giant forest ants leave their subterranean nests to forage for honeydew and insects. Their journeys take them across the forest floor, along human-made sidewalks, and eventually to treetops to gather carbohydrate rich honeydew from sucking insects and to hunt small insects. These gentle giants seemed completely unfazed at being admired by a nosy bug geek.
A giant forest ant from Borneo ogles its puny North American cousin, the odorous house ant. Size differences are accurate and, yes, this image is photo-shopped.
Just how large these giant ants? Well, the regular workers like ones seen in this episode are about 21 mm (0.82 inches) in length while the soldiers which, sadly, we did not see, are larger at 28 mm (1.1 inches). Contrast this massive size with the size of the odorous house ant workers, an ant common here in North America, which run about 3.3 mm (0.1 inches) in length. One can only imagine what a stir giant ants would cause if folks found these wandering around the kitchen in the morning here in the US. Wouldn’t that be amazing?
Acknowledgements
The fascinating articles “Contributions to the life history of the Malaysian giant ant Camponotus gigas (Hymenoptera, Formicidae) by M. Pfeiffer and K.E. Linsenmair and “A briefing on the life history of the giant forest ant Camponotus gigas (pdf) by Martin Pfeiffer were consulted for this episode. We thank Oliver at Tabin Wildlife Reserve and Larry at Mulu National Park for guiding nocturnal rainforest adventures. The keen eyes of Dan, Kristie, Bob, Pat, and Paula helped spot insects for this episode.
