The Sting of the Wild

by Justin O. Schmidt

  Truth, like beauty, can be in the eye of the beholder. Pain truth comes in two flavors, imagined and realized. With stings, our imagination is vivid and strong, even if the sting pain is not realized. The paper wasp, Polistes instabilis, provides a real-life example. Perhaps the name instabilis tells us something. No matter the actual origin of the name, their behavior appears unstable to people walking through the scrubby brush of their tropical habitat. Their presence is usually painfully detected as a nasty sting to the back of the neck or bare arm subsequent to brushing past a leafy tangle with a nest attached to a small branch. This truthful pain was realized by our cowboy guides, as they led a group of biologists on an expedition through the thickets to the most northerly location of the magnificently beautiful military macaws. After the second in line was stung on his wrist and yelled, we all stopped to allow the wasps to return to their nest and become calm, albeit alert. Up to this point, our guides had considered us a bunch of inept, cowardly biologists. We needed to both move forward and change the guides’ perceptions of us. As the only entomologist in the group, I obviously needed to take charge. Here’s where knowledge of stinging insects is crucial. For wasps and bees, the two greatest factors that stimulate attack are human breath and rapid movement. To continue our trek, both factors had to be minimized. Theory is fine, but reality was calling. I carry a 2-liter, wide-mouthed plastic jar for rare opportunities, and this was the perfect occasion. With eyes glued on every movement and hint from the wasps, I held my breath and slowly advanced, jar in my left hand and lid in my right. During this eternity of 30 seconds, the jar was snuggled underneath the nest and the lid just above. Snap. The lid was on the jar and all wasps inside. Except the branch prevented the closing of the lid. A yell for assistance brought a cowboy with a machete to cut off the twig, securing all wasps inside. This reverse showmanship worked: rather than showmanship on the part of the wasps, it was showmanship by the predator, which fooled the wasps and earned biologists some status.

  The Australian bull ants, sometimes called bulldog ants, are inch-long, lithe creatures with enormous eyes, long mandibles, and lightning speed. And they jump. Their uncanny behavior of turning their heads to follow observers adds to their mystique. In Australia, they are highly respected, if not outright feared, for their fabled stinging ability. Among all of Australia’s native insects, bull ants head the list of painful stingers. This is partly because Australia has no native honey bees, no hornets, no yellowjacket wasps, and their social wasps are mostly in the generally placid genus Ropalidia, a group similar to many Polistes paper wasps in Europe and the Americas, though generally milder in disposition. Hence, Australians lack comparisons between their bull ants and other painful stinging insects around the world. Given the background of stories about bull ants, I approached collecting them with some anxiety and caution. However, I didn’t know about their athletic abilities, something mentioned but frequently glossed over by writers of articles on these ants. As I collected some individuals from a nest, an alarm was sent and a boiling mass of ants issued from the colony. My athleticism didn’t match theirs, and the feared stings were realized. I was stunned, not by the pain, but by the low level of pain. The balloon of anticipation had been deflated. Why did the stings not hurt so much? The pain was less than the sting of a honey bee. Flare and swelling were also minimal, and the pain was short-lived. Had I been stung too many times and simply could no longer detect pain? This was a valid concern, so how could I address it?

  As fortune would have it, the greatest congress of social insect scientists was meeting about that time in South Australia. Midway through the meeting we took a break, climbed on some buses, and visited Kangaroo Island. On the return trip, the driver spotted a large bull ant colony along the side of the road and asked whether we would like to stop. A resounding yes echoed throughout the bus. Ah, opportunity. My reputation with insect stings was well established. That set the stage for quiet showmanship and trickery to demonstrate my ability to evaluate pain. Normally, it is unfair to expose people to insect stings, but this group of experienced social insect colleagues was fair game. I went to a colony, picked up individual ants, and dropped them in a jar. Others saw this and realized my approach was much faster and easier than trying to pick up hypermotile ants with clumsy forceps. Sure enough, five colleagues got stung. I ask them casually, “Does it hurt much? How does it compare to a honey bee sting [all had been stung by honey bees]?” In all five cases, the reply was that the sting was surprisingly less painful than expected and hurt less than a honey bee sting. Apparently, my sting pain detection system operates well.

  Truth, lying, and cheating are not solely in the domain of female stinging insects—the ones that can sting—and in humans who exploit or study them. Males of some stinging insects can lie about stings and pain also. Although they have no stinger, no venom, and cannot harm a large predator, males can put on a good show. Because imagined sting pain is real in people and in other animals, male bees and even mimicking flies buzz ferociously when they are captured, as do female bees. The higher-pitched buzzing of a captured insect is an aposematic warning signal that conveys danger. This male auto-mimicry of stinging females is energetically costly and would be very unlikely to have evolved if it were not effective. The sharp spines on male reproductive genitalia, particularly in wasps, have a dual role of matching the structure of the female reproductive system and for providing a modicum of protection against large predators. Like many evolutionary questions, which was a more important selection factor—mate matching or defense—is unclear. Probably both factors were important. In addition to possessing hard, sharp spines, these males exhibit uncanny stinging movements in their similarity to the movements of females. When grabbed, these males curve their abdomens and jab the sharp spines into the fingers or mouth of the offender. Many an experienced entomologist, including me, have been tricked by this maneuver, and our instinct caused the release and escape of the male, to our chagrin. Score one point for the male wasp, zero for the entomologist.

  5

  STING SCIENCE

  In physical science the first essential step in the direction of

  learning any subject is to find principles of numerical reckoning

  and practicable methods for measuring some quality connected

  with it. I often say that when you can measure what you are

  speaking about, and express it in numbers, you know something

  about it; but when you cannot measure it, when you cannot

  express it in numbers, your knowledge is of a meagre and

  unsatisfactory kind; it may be the beginning of knowledge,

  but you have scarcely in your thoughts advanced to the

  state of Science, whatever the matter may be.

  —Lord Kelvin, Popular Lectures and Addresses, 1891–1894

  SCIENCE IS RARELY STERILE. Scientists are adventurers like ancient explorers sailing to undiscovered parts of the globe, who do not know what they will find or discover but seek the thrill of the unknown. Contrary to movie caricatures, scientists are not eccentric, crazy, brilliant people in strange laboratories concocting various magical brews or wild computer programs. Scientists are people, equally exciting or boring, like our usual acquaintances. Science is the process of discovery, distinguishable from other human endeavors. The discovery process is self-correcting; that is, if evidence disproves a scientific concept, that old idea is either discarded or modified consistent with the new factual information. In practice, this process is not usually as smooth or as rapid as described. Most scientists make their greatest discoveries early in their careers and, because they are human, become attached to their discoveries. Within the scientific community, new ideas stimulate new experiments to test the ideas, generating new facts and information. Good scientists will look at new facts and modify or outright discard their ideas if they are shown to be wrong. But this is difficult. Nobody wants to think that much of what he or she accomplished in life is wrong. Young scientist
s are typically spared emotional attachment to earlier ideas and form their ideas mainly based on current facts. Thus, science tends to progress through younger people, and old ideas tend to die with the originators of those ideas. Through this cynical view, science progresses one coffin at a time.

  However imperfect science might be in its practice, it is the best system of discovery of the real world we have. Religion, based on fundamental, often ancient, immutable truths, which can change only painfully slowly and not strongly in response to facts, differs at the most basic level from science. Likewise, science differs from a variety of political systems based mainly on power, authority, and human personality. Science has the uncanny way of progressing, in spite of individual human or institutional personalities and other obstacles, toward ever better understanding of the world and the universe around us. Science is an exploratory process more so than a goal to realize. Yes, there are goals, and these must be clearly defined for funding agencies to support the research, but the real excitement and driving force in science is the adventure of seeking the goal, not in attaining the goal. Attaining the goal is, naturally, exciting for the pride, fame, and satisfaction it brings, but often the opportunities for more funding, talented collaborations, and the ability to continue expeditions into the unknown are more exciting than achieving the goal.

  Ever since I can remember, I was fascinated with ideas and facts. At four years of age, the idea that 10 + 10 = 20 was fascinating. It was a fact: I could count 10 pennies, count into a new pile another separate 10 pennies, then mix the piles and count again. I got 20 pennies. When I was a little older, I remember reading Jean Henri Fabre, the great entomological observer, experimenter, and writer of the late nineteenth and early twentieth centuries. When he was about five years of age, he asked the question, “How do I see?” A simple, but profound question. We take for granted that we see through our eyes, but how many of us ever test that fact? The youthful Fabre designed a scientific test to determine how we see. He closed his eyes and opened his mouth. He couldn’t see. Then he closed his mouth and opened his eyes. He could see. He concluded that we see with our eyes, not our mouths and experimentally demonstrated the fact that we see with our eyes. As trivial as this test was, it hooked me (and apparently Fabre) on the method.

  A kid growing up in rural Pennsylvania has limited opportunities in some respects and enhanced opportunities in others. We had no professional sports teams, no elaborate amusement parks, not many shopping opportunities—the best being a row of toys at the five-and-dime store in the nearest big town—and few organized entertainments nearby. We did have trees, brooks, old abandoned fields, nice pleasant summers, and lots of insects. For unknown reasons, I was not attracted to dinosaurs or other large animals but found tiny insects fascinating, perhaps because they were small like me. They also opened a whole world, just to me, a world not appreciated by the other kids in the neighborhood. Particularly fascinating were the brightly colored paper wasps, yellowjackets, and assorted other solitary stinging wasps and bees. Honey bees were drab brown and not so exciting. The main exciting aspect of bees was their ability to sting. Butterflies, especially tiger swallowtails, were also fascinating because they were big, beautiful, and hard to catch. My parents endured, perhaps encouraged, my interests in nature.

  School became progressively more interesting. First, math. Math was a simple, crisp subject so logical and challenging. Then came biology. Oh, my poor teacher when I fell into a swamp coming out all muddy and smelly after a failed attempt to catch a green darner dragonfly. The next year came physics, a subject radically different in material from biology but fascinating for its own beauty. The following year brought chemistry, my newest love and adventure. Chemistry brought unlimited experimental opportunities, not all appreciated by everyone, for example, the time when my experimental smoke “bomb” produced an enormous mushroom cloud of black smoke. College was next. With chemistry fresh in mind, it became the chosen subject. After six years of chemistry, including a move to the Pacific Northwest for a master’s degree, I found chemistry lab work challenging but lacking. Chemistry lacked living, moving nature—insects to be exact. Stinging insects were still etched in my memories. Armed with renewed memories and enthusiasm, a move to Georgia was in order.

  At the University of Georgia, I found myself among a group of bright students, all of whom had graduated from biology or zoology programs and were well ahead of me in many aspects of entomology. As an undergraduate, I was exempted from the biology requirement and did not take a single course in biology. In graduate school, I was among students and faculty who called insects by their scientific names. I knew the common names of the insects but not any scientific names. When it came to picking dissertation research, a natural was to combine what I knew best, chemistry, with what I loved, stinging insects. My professor, Murray Blum, wisely suggested I work on Pogonomyrmex harvester ants, locally available and nasty stinging insects whose venom chemistry was unknown.

  With that goal in mind, off I went with Debbie, a talented zoology student who fortuitously happened to be my wife. We piled buckets in the car’s trunk and, with shovels in hand, headed on an expedition to find harvester ants. The procedure was simple enough: find the ants; dig up the colony; put ants, dirt and all, into a bucket; and bring them back to the lab to study. Digging in the sandy soil of Georgia was a delight, not like digging in the limestone-laden rocky soils of the rural Pennsylvania Appalachian Mountains. We quickly got casual and relaxed at the easy work in an idyllic setting. Wham, an ant stung me. Serendipity had struck. This was no ordinary sting. This sting really hurt. The pain, delayed at first, became piercing and excruciating. Then, it progressed into waves of deep throbbing visceral pain, as Debbie, who also got stung in the operation, described as “deep ripping and tearing pain, as if someone were reaching below the skin and ripping muscles and tendons; except the ripping continued with each crescendo of pain.” The pain was not at all like the hot burning pain produced by all my childhood experiences with stinging insects. All the stings of my childhood world of honey bees, yellowjackets, baldfaced hornets, bumble bees, and paper wasps resembled the pain of a burning match head that flipped off its stick and landed on my arm. All of these immediate, intense pains lasted only 5 minutes or less before receding to a tolerable, if not benign, level. Harvester ant stings were different. Not only was the sensation less burning, it lasted … and lasted. Four hours later, we were still in pain, albeit decreasing pain. After 8 hours, the last vestiges of pain were finally gone. From a chemist’s and biologist’s viewpoint, even more interesting were the other reactions. Harvester ant stings caused the hairs around the sting site to stand up on end, much like the bristling shoulder hairs on a frightened dog. There was no fright though. Something independent of the brain made these hairs stand up. Also, the area around the sting became moist with sweat, again something independent of the brain. No other insect stings we, or others, had experienced ever caused either of those reactions.

  Thus, an interest in stings, their chemistry, biochemistry, physiology, and their biological roles in the lives of the insects and their targets was born. Two immediate questions came to mind. First, do all harvester ant species cause the same types of reactions? Second, do any other stinging insects cause similar reactions? These were untested ideas. Ideas are great but are not meaningful if no data exist to test them. Data were needed. Off we set on an entomological adventure to the western United States in search of data. With shovels, insect nets, maps, containers, a portable microscope, reference books, and ice chests all crammed into our old VW camper bus, we were on our way. The primary goals were to collect as many of the 20-some-odd species known at the time in the United States as possible, to collect their venom for investigation back in the lab, and to bring back live colonies. Our indirect goals were to compare the sting painfulness and reactions of the species. We had no desire to be intentionally stung, but if we did get stung, we might as well be prepared to record the data. Wasting a goo
d opportunity for a data point seemed crazy.