Wicked Bugs

by Amy Stewart

  In Iraq, the bugs swarm around the lights where troops are stationed in the evening.

  Outbreaks of Paederus beetle dermatitis have been a vexing problem on military bases around the world, where bright lights attract the bugs and soldiers might not know to avoid them. In Iraq, the bugs swarm around the lights where troops are stationed in the evening. While bug zappers are widely used on military bases, with the intention of making the area immediately around them a safe place for soldiers to congregate, the Paederus beetles are drawn to the light of the zappers but are not killed by their electrical charge. Soldiers are urged to keep their sleeves rolled down and their uniforms tucked in, a difficult task in the desert heat.

  The Paederus beetle is a small, skinny creature with alternating red and black segments and extremely short wing covers that don’t resemble wings at all (some species are not even capable of flight). They could easily be mistaken for earwigs or large ants. While the beetles may be annoying in large numbers, they do prey on smaller bugs, including some serious agricultural pests, so farmers generally welcome them in spite of the risks they pose to workers in the field.

  There is some speculation that the Paederus beetle is the source of a mysterious legend about a bird that excreted poison droppings. Ctesias, a Greek physician who wrote an account of India in the fifth century BC, described a poison that appeared in the droppings of a tiny orange bird. “Its dung has a peculiar property,” he wrote, “for if a quantity of it no bigger than a grain of millet be dissolved into a potion, it would be enough to kill a man by the fall of evening.” No trace of this poisonous bird, which he called dikairon, has ever been found. Some historians speculate that the actual poison was not a bird dropping, but the bright orange and black Paederus beetle, which sometimes lives in the nests of birds and could be mistaken for droppings. A beetle fitting this description was also known in Chinese medicine as far back as 739 AD as a poison so strong it could remove tattoos, boils, or ringworm. It may have a medical use today as well: the poison, pederin, inhibits cell growth and is under investigation as a possible antitumor agent for use in cancer treatment.

  Meet the Relatives There are roughly 620 species of Paederus beetles worldwide. They are a member of the rove beetle family, which includes the devil’s coach-horse beetle, Ocypus olens, a large European beetle that looks threatening and will bite if provoked, but which is otherwise harmless.

  HORRIBLE

  CORPSE-EATERS

  The science of forensic entomology—the study of insects to determine the time, location, or circumstances of a death—is not particularly new. A book called The Washing Away of Wrongs, written in China in 1235, described how an infestation of flies on a corpse could provide clues in a crime investigation. It even told of a murder that was solved by watching what flies did when the villagers came together and laid out their sickles for inspection. The flies landed on one sickle in particular, perhaps because traces of tissue and blood were present. Confronted with this evidence, the owner of the sickle confessed to having used it to commit the crime.

  These methods are still in use today. In 2003, University of California–Davis entomologist Lynn Kimsey received a visit from a police officer and two FBI agents. They wanted to know if she could inspect the bugs smashed against a car’s radiator and air filter to determine what states the car had driven through. Their theory was that the suspect, a man named Vincent Brothers, had driven from Ohio to California to murder his family. He claimed he never left Ohio. Kimsey agreed to have a look.

  There were thirty different insects on the car, but they weren’t intact: she had to make her identifications from fragments of wings and legs and smashed bodies. She found a grasshopper, a wasp, and two other bugs that could only have been picked up during a drive through the West. At the 2007 trial she testified for five hours, and the jury eventually convicted Brothers of murder.

  The most common use of forensic entomology is in establishing the time frame within which a death occurred. By examining the species of insects that inhabit a corpse, and correlating that with weather data and other information about the crime scene, it is possible to estimate how long a person has been dead, whether the person was wounded before death, and whether the corpse was moved at any point after the crime.

  BLOW FLIES

  Also called carrion flies, blow flies come from the family Calliphoridae. These blue-green flies are usually the first on the scene after a death, thanks in part to their ability to smell a corpse from over a hundred feet away. They have been known to arrive as quickly as ten minutes after a death occurs, and might lay thousands of eggs in the body. The extent to which those eggs have hatched and moved through their stages of development can help pinpoint the time of a recent death. The answers don’t always come quickly, though: sometimes entomologists have to collect the eggs and wait for them to hatch, then count backward to determine the estimated time of death.

  Blow flies in the Calliphora genus develop quickly from egg to larva to pupa, and that process is accelerated in hot weather, making it important for investigators to know what the temperature has been so that they can correlate that with the size of the creature.

  Cocaine also accelerates the maggots’ growth. Entomologist M. Lee Goff was called in to clarify an important point of confusion in a murder case in Spokane, Washington. Some of the larvae found on the victim were so large that they appeared to be three weeks old, while others were quite small and would suggest a time of death of only a few days prior. He was able to determine that the larger larvae had been feeding around the victim’s nose and that she had been using cocaine shortly before she died. Once the discrepancy in the size of the bugs was cleared up, police were able to rule on a precise time of death.

  ROVE BEETLES

  Rove beetles in the family Staphylinidae might be among the next insects to appear as the deceased enters a not-quite-as-fresh stage. They are attracted primarily to fly larvae, which means that they tend to show up and devour whatever evidence the first wave of flies have left behind.

  BURYING BEETLES

  These members of the genus Nicrophorus are attracted to carcasses by their scent and usually turn up to find out if the body is something they are capable of burying. Their reasons have to do with their unique life cycle: when burying beetles find a dead mouse, bird, or other small animal, they actually dig a hole, lining it with fur or feathers they strip from the body, creating a kind of crypt. Often several pairs of beetles will join together in this effort, spending an entire day on the burial process. Once the corpse is completely covered—and therefore protected from other predators—the females lay their eggs inside the crypt so their young will have a food source when they hatch. They even stick around to tend to the brood, making them one of the few insects who actually care for their young.

  In the case of a human carcass, the beetles are often found under the body, burying small bits of flesh, possibly tampering with important evidence. They may also lay eggs inside the body since it is too large to bury. There have been cases of the beetles breeding inside stab wounds, for instance. They eat blowfly larvae and sometimes carry tiny mites that feed on blowfly eggs as well, so their arrival on the scene can interfere with the critical information that blowfly eggs and larvae provide.

  MITES

  These critters arrive in stages as well. The first group are gamasid mites, which ride around on beetles and feed on the eggs of the first wave of flies. Later in the process, tyroglyphid mites, also known as mold mites, show up to feed on mold, fungi, and dry skin.

  SKIN BEETLES

  In the family Dermestidae, skin beetles are called late-stage scavengers because they often appear a couple of months after death has occurred. These are the beetles used in natural history museums to clean animal skeletons being prepared for display. Another family of beetles may appear later in a corpse’s decomposition: the so-called ham beetles in the family Cleridae, which get their name from their habit of infesting dried meats. They have been foun
d in tombs and on Egyptian mummies.

  By examining the species of insects that inhabit a corpse, it is possible to estimate how long a person has been dead and whether the corpse was moved after the crime.

  DESTRUCTIVE

  Phylloxera

  DAKTULOSPHAIRA VITIFOLIAE

  In the mid-1800s, the French wine industry dominated the world market. One in three French citizens made their living from wine. The quality of the vines, the richness of the soil, and the expertise of the winemakers combined to produce wines of extraordinary quality. French physicians recommended drinking wine three times a day, forsaking tea and coffee. People were happy to oblige: the average French citizen was drinking eighty liters, or about one hundred bottles of wine, every year.

  And then came the Americans.

  Native North American grapevines had failed to produce impressive wines, so Americans took to importing European varieties to help start a domestic wine industry. And French viticulturalists, in turn, planted a few American vines, although they were more a botanical curiosity than a serious crop. These exchanges looked like the beginning of a congenial friendship—until problems started to develop with the vines.

  SIZE:

  1 mm

  FAMILY:

  Phylloxeridae

  HABITAT:

  Vineyards

  DISTRIBUTION:

  Found in various wine-growing regions around the world, including the United States, Europe, Australia, and parts of South America

  Americans noticed that European vines planted in the United States sometimes failed to thrive. The leaves would turn yellow, dry up, and die. When the dead vines were pulled out of the ground, farmers found no trace of a predator or a disease. Even more alarming was the fact that French vines were starting to succumb to similar maladies. An international search began to find a solution to the problem.

  By 1868 French botanists had discovered the culprit: a tiny aphid-like insect they called Phylloxera vastatrix (later renamed Daktulosphaira vitifoliae). It sucked the sap of living plants and moved on when they died, which explains why it was never found on the dead vines. Later it would become clear that the insect had hitched a ride to France on a native American vine. But for the moment, the only matter that concerned the French was finding a way to kill the insect and restore their industry. First they needed to understand the phylloxera’s life cycle.

  They discovered that this bug had one of the most bizarre life cycles of any creature they’d ever encountered. It begins when a female phylloxera called a “fundatrix” hatches from an egg and immediately starts to drink from the leaf she was born on. This triggers a hormone in the plant that forms a protective growth called a gall around her. Before long she grows into an adult and—without ever having gone on a single date, much less mated—she lays about five hundred female eggs inside that gall, then dies.

  The next generation of females hatch and repeat the process, also forming galls and laying eggs without ever mating. This goes on for months, with perhaps five successive generations hatching, laying astonishing numbers of eggs, and then dying. A single fundatrix female might be responsible for billions of young phylloxera by the time the season is over, sucking the life out of the vines all the while.

  The season’s last generation falls to the ground and takes up residence in the roots, where a thousand of them might inhabit one ounce of living rootstock. Some hibernate through the winter, and, in the spring, the generation that emerges has wings and is capable of flying to nearby vineyards. Some of these winged creatures lay female eggs, and others lay male eggs. The generation that hatches at that point has only one goal—to make up for the lack of sexual activity on the part of its ancestors. The male doesn’t eat—it doesn’t even have a mouth or an anus—so it does nothing but mate until death. The females of this generation are capable of laying fundatrix eggs that can begin the whole cycle all over again. At this rate of reproduction, it doesn’t take long to bleed the vineyards dry and introduce secondary fungal infections that ensure the end of the grape harvest.

  Figuring this out was understandably complicated. But the question of what to do next was even more vexing. Although it was difficult for the French to admit, the only solution was to turn to the very vines that had brought the problem to France in the first place. Native American vines were naturally resistant to this American pest, and grafting fine European vines onto the rough-and-tumble American rootstocks proved to be the only way to save the French wine industry.

  But how would the wine taste? French scientist Jules Lichtenstein stated firmly in 1878 that “the vines of France are doomed . . . but the wines of France will live again, reborn on the resistant rootstocks of America.” French wines were indeed saved from the phylloxera by the American vines and went on to dominate the world once again. But even today, wines grown on rare pockets of pre-phylloxera vines (including vines in Chile planted by Spaniards centuries ago) are still highly sought after by connoisseurs.

  Meet the Relatives Phylloxera are related to a number of other bugs with sucking mouthparts, including aphids, leafhoppers, and cicadas.

  The only matter that concerned the French was finding a way to kill the insect and restore their wine industry.

  DESTRUCTIVE

  Rocky Mountain Locust

  MELANOPLUS SPRETUS

  Aplague of locusts swept across the American West in the summer of 1875. Farmers watched in horror as a dark shape rose from the horizon and advanced across the sky, moving faster than any thunderstorm or tornado they’d ever seen. The sun dimmed and vanished, the sky filled with a strange buzzing, crackling sound, and then, all at once, the locusts descended.

  It happened so quickly that parents had to grab their children and run for shelter. Locusts swarmed over every inch of the cornfields, covered homes and barns, devoured trees and bushes, and even massed indoors so that the floors and walls were thick with them. There seemed to be no end to the assault: millions dropped out of the sky, but millions more moved on to the next county and the one after that.

  SIZE:

  35 mm

  FAMILY:

  Acrididae

  HABITAT:

  Meadows and prairies

  in the American West

  DISTRIBUTION:

  North America

  The sheer volume of locusts that a swarm delivers is almost impossible to grasp. Witnesses reported tree branches breaking under the weight of the insects. A layer of insects six inches deep covered the ground. The locusts clogged rivers and their bodies washed into the Great Salt Lake by the ton, creating a putrid wall of brined corpses that reached six feet tall and extended for two miles around the lake.

  The locusts swarmed so quickly that parents had to grab their children and run for shelter.

  The size of that ferocious swarm was estimated at 198,000 square miles—larger than the state of California—and it contained about 3.5 trillion locusts. They completely destroyed crops and bred with frightening speed and efficiency: one square inch of soil could hold 150 eggs. Even if only a fraction of them survived, a typical farm could be left with no crops and enough eggs buried in the soil to produce thirty million more locusts. When the larvae hatched in the spring, it looked like the ground was boiling with them.

  This pestilence created widespread poverty and starvation across the Great Plains. Some states offered locust bounties to farmers, paying a few dollars for a bushel of eggs or nymphs in an attempt to rid the land of the insects while providing income for its destitute citizens. Some enterprising farmers turned their flocks of chickens and turkeys loose on the swarms, hoping that the free protein source would turn a tragedy into an opportunity. But instead, the birds gorged themselves on the bugs, literally eating themselves to death. The diet of locusts even tainted their flesh, making the birds inedible. Farmers set fires in their fields, doused the soil with kerosene, and resorted to any poison or potion they could get their hands on, but nothing worked. The locusts continued to sweep across the la
ndscape throughout the late 1800s, leaving devastation and mass starvation in their wake.

  Little was understood at the time about the life cycle of the Rocky Mountain locust. A locust, entomologists now know, is little more than a grasshopper under pressure. A Russian entomologist named Boris Uvarov, working in the 1920s, proved that certain species of ordinary-looking grasshoppers were capable of undergoing a remarkable transformation during times of stress.

  Grasshoppers usually forage alone, spreading out across large areas when food is plentiful. But during a drought, the creatures might be crowded together, and that proximity brings on chemical changes that cause the females to lay very different eggs. The nymphs that hatch from those eggs grow longer wings, have a propensity to live more closely together and travel in dense packs, and are themselves capable of laying eggs that can survive longer periods of dormancy. They even change color. In essence, a fairly benign, stable grasshopper population transforms itself into something entirely different—a migratory plague of locusts capable of swarming and devouring everything in its path.

  This explains why the settlers claimed to have never seen these particular locusts before the ominous swarms arrived, and why plagues of locusts have always been seen as having some divine origin. They are entirely unfamiliar creatures, having transformed themselves from ordinary grasshoppers to larger, darker, never-before-seen invaders.