by Amy Stewart
Meet the Relatives This family of flies includes the common housefly, Musca domestica, and stable flies.
HORRIBLE
I’VE GOT YOU UNDER MY SKIN
The most dedicated bug-hater can be persuaded to consider the merits of a beetle or a spider, an ant or a centipede. They have their uses, their interesting habits, their own strange and intricate beauty. But nobody loves a maggot. Even the name elicits a shudder of disgust.
These white, wormy creatures are nothing more than baby flies, and no more or less grotesque than any other insect’s offspring. They can usually be found clustered around some food source their mother has found for them, and they’re doing nothing but eating and growing as children should. What’s so offensive about that?
Nothing, except when the thing they are eating is us.
HUMAN BOT FLY
Dermatobia hominis
Travelers returning from Mexico and Central America sometimes come home with more than a great tan. The human bot fly can hitch a ride with tourists, making itself known only when a sore resembling an insect bite doesn’t get better.
This fly has an ingenious method of getting under people’s skin. It can crawl right into an open wound, but an even more effective strategy is to capture a mosquito, lay eggs on the mosquito, and let it go off in search of a warm-blooded human. The eggs may simply fall off the mosquito when it lands on an arm or a leg, or they may hatch at the moment the mosquito makes contact, enlivened by the warmth of the human host. As the eggs hatch, the larvae crawl right off the mosquito and into the wound it has created. And if there is no mosquito available, a bot fly will happily use a tick for transportation, instead.
If left undisturbed, the larvae will settle under the skin and feed for two to three months before emerging on their own to drop to the ground and pupate. But most people, when confronted with a wound that never quite heals and the uncomfortable feeling that something is moving around under the skin, will not leave it undisturbed. The wound can be painful and itchy, it can ooze a foul-smelling liquid, and some people even claim they can hear the creature moving around. The only consolation is that these wounds rarely become infected, thanks to an antibacterial secretion from the larva itself.
Extraction of a bot fly larva is not always easy, depending on the location of the bite and the overall health of the human host. Some people are sent home and told to wait it out, which can be intolerable for all but the most entomologically curious. Some try to smother it by covering the wound with tape, nail polish, or petroleum jelly, hoping to weaken the larva and pull it out more easily. Doctors have used a simple first aid tool called a venom extractor to remove the creature, and a surgical extraction is sometimes possible, as long as the entire larva can be cleanly removed. One home remedy is to leave a piece of raw bacon over the wound on the theory that the maggot will prefer bacon to human flesh and will leave voluntarily for this new food source.
Any creature with a name like hominivorax—“eater of man”—is best avoided.
SCREW-WORM FLY
Cochliomyiahominivorax
Any creature with a name like hominivorax — “eater of man” — is best avoided. U.S. agricultural officials knew this when, in 1958, they began an extraordinarily sophisticated campaign to eradicate the fly. They exposed male screw-worm flies to radiation, rendering them sterile, then released them throughout the South. Once those sterile males mated with females, the females would, in all probability, die without mating again, which would bring their life cycle to an end.
Thanks to those efforts, the screw-worm fly was entirely eliminated from the United States, with only sporadic outbreaks that have been fairly easy to treat. This is good news for the livestock the flies were attacking — and for humans, as well.
A pregnant female will lay two hundred to three hundred eggs around a wound or at the edges of mucus membranes — in the eyes, ears, nose, mouth, or genitals of humans and other animals, including cattle. Once the eggs hatch and the larvae start feeding, more females are drawn to the site and they, too, lay eggs. The larvae burrow deeply into the wound, earning them the name screw-worm for the way they screw themselves into the flesh and enlarge the wound, introducing the risk of infection. The larvae live inside their host for about a week, then drop to the ground to pupate.
A 1952 case from central California illustrates the problem these flies once posed in the United States. A man who was lounging in his backyard kept swatting at a fly buzzing around his head. The fly disappeared momentarily, but then the man felt a strange itch in his nose. When he blew his nose, the fly came out. Over the next few days one side of his face became so swollen that he went to the doctor. The doctor irrigated his nasal passages and washed out twenty-five maggots. It took eleven more days of irrigation to remove all two hundred maggots that resulted from the fly making one brief visit to the inside of the man’s nose.
While the so-called New World screw-worm fly is mostly a dim memory in the United States, it is still found in Central and South America. Another species, the Old World screw-worm Chrysomya bezziana, is found in Africa, Southeast Asia, India, and the Middle East. Doctors have noticed that an increase in adventure sports and “Amazing Race”–style treks through jungles and deserts have caused a new generation of Americans and Europeans to become reacquainted with the screw-worm fly.
TUMBU FLY
Cordylobia anthropophaga
In sub-Saharan Africa, people dread the arrival of the tumbu fly, whose females lay up to three hundred eggs at a time in the sandy soil, preferably soil contaminated with excrement if they can find it. They are also drawn to clean laundry that has been hung out to dry, depositing their eggs there so frequently that the locals — those who can afford it — know to place their clothes in a hot dryer or iron them to kill the eggs.
Once the eggs hatch, the larvae are able to burrow into healthy, unbroken skin, often without their victim noticing or feeling any pain at all. Over the next few days a nasty boil develops which, if left untreated, will itch and hurt and leak a vile fluid made up of a mixture of blood and the bodily waste of the larvae.
The larvae will leave on their own after two weeks if they aren’t forcibly removed first. Although the tumbu fly is only found in Africa, cases have turned up elsewhere, presumably because the eggs hitched a ride on a blanket or article of clothing coming from the continent.
SCUTTLE FLY
Megaselia scalaris
This fly, which is found worldwide, gets its name from its habit of scuttling around with short, jerky motions. It has also earned the name “coffin fly,” as one of many flies that are attracted to dead bodies. Unfortunately, it is found among the living, too.
Scuttle flies are also known for their horrid attraction to the urinary tract. Cases of urogenital myiasis — infestations of eggs and larva in the urinary or genital areas by scuttle flies — have been documented in areas of poor hygiene, particularly when some sort of wound or infection was already present.
In 2004, an Iranian man working in Kuwait was injured when concrete at a building site fell on him. At the hospital he was treated for fractures and lacerations. After two weeks, scuttle fly maggots emerged from his wound while the bandage was being changed. By calculating the age of the larvae, hospital administrators were able to determine that the man had been infected at the hospital, and that the flies would have had to crawl under his bandage to lay their eggs.
CONGO FLOOR MAGGOT
Auchmeromyia senegalensis
People living in huts south of the Sahara are well-advised to stay off the ground. The Congo floor maggot flies like to lay their eggs on the warm, dry floors of huts or in caves and barns where animals are sheltered. When the larvae hatch, they wander around on the floor at night looking for a warm-blooded creature to feed upon. They will bite humans in the night and drink their blood for about twenty minutes at a time, but apart from painful, swollen bites, they don’t transmit disease or burrow under the skin. People who sleep on mats are u
nable to avoid being bitten, but those lucky enough to sleep in a bed are rarely bothered by these night-time bloodsuckers.
Nobody loves a maggot. Even the name elicits a shudder of disgust.
DESTRUCTIVE
Formosan Subterranean Termite
COPTOTERMES FORMOSANUS
Judging from recent news stories,” said entomologist Mark Hunter in 2000, “the Formosan termite appears determined to consume the historic French Quarter of New Orleans. These termites destroy creosote-treated utility poles and wharves, the switch boxes of underground traffic lights, underground telephone cables, live trees and shrubs and the seals on high pressure water lines.” At that time he predicted that this invasive Asian termite would be the greatest challenge in the war between humans and insects going into the twenty-first century.
SIZE:
15 mm
FAMILY:
Rhinotermitidae
HABITAT:
Found underground, in trees, or in attics and crawl spaces of wood structures.
DISTRIBUTION:
Taiwan, China, Japan, Hawaii, South Africa, Sri Lanka, southeastern United States
Unfortunately, five years later, Hurricane Katrina proved him right. The most devastating natural disaster in U.S. history killed 1,833 people; it also displaced three-quarters of a million more, making it responsible for the largest mass migration since the Dust Bowl. When the damages were finally tallied, they reached almost $100 billion. And as New Orleans started to rebuild, it became clear that the pest that has plagued this city for decades may have played a role in its destruction. The seams of the flood-walls that were supposed to protect the city were made of sugarcane waste, a treat that Formosan termites cannot resist.
Could any of this have been prevented? Seventeen years before Katrina, the Formosan termite lost its most dedicated foe. Jeffery LaFage, a Louisiana State University AgCenter entomologist, was out for dinner in the French Quarter in 1989 to celebrate the start of his new program to eliminate termites from the Quarter. As he walked through the Quarter with a friend after dinner, a robber approached them both and shot and killed Jeffery. His death set termite control in the area back by years.
The seams of the New Orleans floodwalls were made of sugarcane waste, a treat that Formosan termites cannot resist.
Fellow AgCenter entomologist Gregg Henderson took up the fight. He sounded the alarm about the infestation of termites in the floodwalls five years before Katrina came ashore, then watched in horror as his worst predictions came true. “I remember watching the news as the floodwalls and levees broke,” he said. “I started to get that sick feeling, when you know something’s wrong.” While poor planning and maintenance certainly contributed to their failure, the role of the Formosan termite could not be overlooked. Henderson has since developed a program to lure termites away from the floodwalls, to places where they could be more easily captured and killed, but he’s been unable to get officials interested in his ideas.
Formosan termites have been a problem in New Orleans for decades. The creatures seem to have arrived onboard ships returning to port after World War II. New Orleans’ damp, tropical climate and abundant supply of old wood-frame buildings offer the perfect breeding ground for the pest. The French Quarter’s row houses make it especially easy for the termites to flourish: any efforts at control undertaken in one building would simply encourage the insects to move next door. Before Katrina hit, the city’s residents were losing an estimated $300 million per year to termite damage.
A Formosan termite queen can live for up to twenty-five years, enjoying both a steady supply of food delivered by her workers and romantic assignations with the king termite, whose sole job is to mate with her. Every day she lays hundreds — or perhaps thousands — of eggs. When the larvae hatch, they are fed by worker termites and then grow up to be either workers themselves, who eat wood and feed the colony; soldiers, who use specialized defenses to kill attackers; or nymphs that develop into supplemental kings and queens or “alates,” winged creatures that are capable of becoming kings and queens of their own colonies. The swarms of alates around lampposts in the French Quarter from late April through June are so dense that they actually dim the lights and send tourists running.
Some pest control experts hoped that Hurricane Katrina would have one silver lining — a mass drowning of Formosan termites. Unfortunately, the termites were undeterred. The insects build homes for themselves out of digested wood, feces, and spit; these cartons contain intricate networks of tiny chambers and corridors that hold colonies of several million. The cartons kept most colonies safe and dry throughout the hurricane and the flooding that followed. With home and business owners abandoning both their buildings and the careful regimen of pest control they’d been following to limit their spread, the conditions are perfect for the termite to rise again.
Meet the Relatives About twenty-eight hundred species of termites have been identified worldwide.
PAINFUL
THE ANTS GO MARCHING
Justin Schmidt, an entomologist who studies venomous stings, created the Schmidt Sting Pain Index to quantify the pain inflicted by ants and other stinging creatures. His surprisingly poetic descriptions give some order to the hierarchy of ant stings as compared to those of bees and wasps:
1.0 Sweat bee: Light, ephemeral, almost fruity. A tiny spark has singed a single hair on your arm.
1.2 Fire ant: Sharp, sudden, mildly alarming. Like walking across a shag carpet & reaching for the light switch.
1.8 Bullhorn acacia ant: A rare, piercing, elevated sort of pain. Someone has fired a staple into your cheek.
2.0 Bald-faced hornet: Rich, hearty, slightly crunchy. Similar to getting your hand mashed in a revolving door.
2.0 Yellowjacket: Hot and smoky, almost irreverent. Imagine W. C. Fields extinguishing a cigar on tongue.
2.x Honey bee and European hornet: Like a matchhead that flips off and burns on your skin.
3.0 Red harvester ant: Bold and unrelenting. Somebody is using a drill to excavate your ingrown toenail.
4.0 Tarantula hawk: Blinding, fierce, shockingly electric. A running hair drier has been dropped into your bubble bath.
4.0+ Bullet ant: Pure, intense, brilliant pain. Like fire-walking over flaming charcoal with a 3-inch rusty nail in your heel.
Ants are incredibly useful, acting as shredders to break down organic matter and recycle nutrients back into the soil and serving as a food source for other small creatures in the food chain. They are also a marvel of social organization, maintaining complex colonies with divisions of labor, sophisticated communication, and the remarkable ability to act as a group to carry out their missions. They wage war, maintain farms of fungus, and build intricate nests with chambers for day care centers and other functions important to the community. But the behavior of some ants is not just fascinating — it’s terrifying and, in some cases, brilliantly painful.
FIRE ANT
Solenopsis invicta
Also known as the red imported fire ant (RIFA), this South American native forms colonies of up to 250,000 members that feed on aphid secretions, as well as dead animals, worms, and other insects. They can take over the nests of birds and rodents, devour the shoots of crops like soybeans and corn, and even disable farm equipment.
Their ability to tamper with mechanical and electrical systems is particularly vexing. They chew on the insulation around wiring, switches, and controls, resulting in tractors that won’t start, electrical circuits that short out, and air conditioners that won’t operate. They have disabled traffic lights and even imperiled the now-defunct supercollider project in central Texas. In all, the damage caused by fire ants in the United States exceeds $2 billion per year.
But most people fear the fire ant for its vicious sting. Roughly a third to a half of all people living in the fire ant’s path — an area extending from New Mexico to North Carolina — get bitten every year. When fire ants attack, usually in response to someone accidentally stumbling i
nto a colony, they bite hard to get a good grip, then inject their venom, causing immediate pain at the site of the sting. If the ant isn’t knocked off, it will sting a few more times in the same area. These bites raise a red welt with a white pustule in the center.
A severe attack, and the scratching that often follows it, can introduce infection and leave scars. People working on construction or landscaping crews risk getting hundreds of bites at once when they stumble across a colony — sometimes resulting in extreme swelling of an arm or a leg, which can last a month or longer. In 2006, a South Carolina woman died from such an attack while gardening, as a result of the same kind of anaphylactic shock that affects some people after bee stings.
The attempts to control fire ants has been so expensive, time-consuming, and ineffective that biologist E. O. Wilson has called it the “Vietnam of entomology.” Chemical sprays only wiped out the competition, making it easier for fire ants to get established. Now authorities in Australia are actually hunting them by helicopter, using heat-sensing equipment to locate the enormous mounds so that pesticides can be injected directly into the ants’ homes.
DRIVER ANTS
Dorylus sp.
When driver ants are hungry, they hit the road. In leaderless swarms, they stream through villages in central and east Africa, decimating everything in their path. As many as twenty million ants join the swarm, enough to build tunnels as they go and overpower grasshoppers, worms, beetles, and even larger creatures like snakes and rats. Because these inch-long ants barrel right through villages and homes, people may be forced to move out during the onslaught. This is not always such a bad thing; the ants wipe out cockroaches, scorpions, and other household pests during their march.
