Mother Earth Living

4 Wicked Bugs: Mosquitoes, Chigger Mites and More

With wit, style and exacting research, Amy Stewart has uncovered the most terrifying and titillating stories of bugs gone wild. Her book, Wicked Bugs (Algonquin Books of Chapel Hill, 2011), delves into the extraordinary powers of six- and eight-legged creatures. In this excerpt from the book’s introduction and four of its bug features, learn about the thrilling and frightening potential of four wicked bugs that can be found in most any home or garden: the bed bug, brown recluse, chigger mite and mosquito.

Warning: We Are Seriously Outnumbered

In 1909, the Chicago Daily Tribune ran an article titled “If Bugs Were the Size of Men.” It began with this ominous statement: “All the powers of destruction that were ever invented by man are puerile and absurd compared with those with which nature has invested insects.” The reporter went on to ask what would happen “if some mighty magician’s wand should be waved over the world tomorrow and mankind be reduced to the size of insects, while these tiny creatures should reach the size of men.”

Chicagoans must have read with alarm of the calamities that would befall them if they were to trade places with bugs: the giant Hercules beetle was not just formidable, but immoral, with a taste for drinking and brawling; bark beetles would mow down massive fortresses; armies would be helpless against the artillery of the bombardier beetle; and spiders would “destroy elephants . . . a man’s only possible salvation would be that he was too insignificant to attack.” Even lions would cower in fear against these new winged and multilegged enemies.

The reporter’s intent was, undoubtedly, to make the point that insects are powerful in their own way and to suggest that only their diminutive size keeps them from conquering the world.

If only that were true. In fact, insects have changed the course of history. They have halted soldiers in their tracks. They have driven farmers off their land. They have devoured cities and forests, and inflicted pain, suffering, and death upon hundreds of millions.

This is not to say that they don’t do good as well. They pollinate the plants that feed us, and they are themselves food for creatures up and down the food chain. They do the vital work of decomposition, returning everything from fallen leaves to fallen heroes back to the earth. Any number of insects, from the blow fly to the blister beetle, have proven useful in medicine. And they prey on one another, keeping pests in check. We could not live without them. In fact, indiscriminate pesticide use and destruction of insect habitats is far more harmful than simply learning to live alongside them and to appreciate their finer qualities.

But I am not here to celebrate their virtues; I have devoted myself exclusively to the dark side of the relationship between nature and humans. Some might say that people already harbor enough hatred of insects and need no further encouragement. And those of us who are staunchly on the side of bugs, sweeping them gently out of the house with a word of kindness and refusing to allow chemical sprays into our gardens for fear of disturbing their dinner, might be disinclined to explore their criminal history.

However, our affections can be as misleading as our phobias. The common garden spider on your windowsill deserves applause for her good deeds, but the bloodsucking assassin bug you encounter on a South American vacation should be given a wide berth. Learning to make such distinctions doesn’t require an entomology degree; a little common sense and an open-minded curiosity is all you need.

Bed Bug (Cimex lectularius)

Size: 4-5 mm
Family: Cimicidae
Habitat: Nests, caves, and other warm, dry places near food sources
Distribution: Temperate regions throughout the world

(See the Image Gallery for an illustrated image of the wicked bed bug.)

In Toronto, a 60-year-old man went to his doctor complaining of fatigue. He was diabetic, a recovering alcoholic with only a year’s sobriety, and a former crack cocaine user, so fatigue was the least of his problems. But the doctor found severe anemia, which he treated with a prescription dose of iron. A month later the man was back with even worse symptoms, requiring a blood transfusion before he could return home. A few weeks later, he needed another transfusion. The blood loss was inexplicable and frightening.

Then the doctor paid a call to his patient at home. The problem was immediately apparent: bed bugs were everywhere. He could even see them crawling on the man during the visit. The public health department was called in; after the apartment was sprayed with insecticide and the old furniture removed, the man gradually recovered.

The bed bug travels at night, lurking in low light, feeling its way toward warmth and the tantalizing odor of carbon dioxide. It approaches its dinner–that is, you–with outstretched antennae, gripping the skin tightly with tiny claws. Once it has a good grip, it begins rocking back and forth, working needlelike feeding organs called stylets into the skin. It bites gently, piercing the skin just enough to get the blood flowing. The stylets probe around under the skin in search of a good-sized blood vessel to tap into. The bed bug’s saliva contains an anticoagulant to prevent clotting, so it can settle down and feed. If it is left alone to enjoy its meal, it will feed for about five minutes and then wander off. But if you were to swat at the bug in your sleep, it would probably move a short distance away and bite again, leading to a telltale series of three sequential puncture wounds. Dermatologists call these bites “breakfast, lunch, and dinner.”

Before World War II, bed bugs were a fact of life in the United States and around the world. Pesticides developed around that time helped eliminate them, but now the blood-sucking parasite is back. Reasons for its reappearance include an increase in international travel, a reduction in the use of broad-spectrum pesticides in favor of targeted baits, and, alarmingly, the bed bugs’ own resistance to chemical controls. Researchers at the University of Massachusetts have reported that bed bugs in New York City show new mutations in nerve cells that allow them to survive exposure to neurotoxic ingredients in bug sprays. In particular, they found that pyrethroid sprays, the synthetic version of a natural insecticide derived from chrysanthemum flowers, had little effect on New York bed bugs, while a population collected in Florida was easily wiped out by the poisons.

What has this meant for the average New Yorker? Although bed bugs have not been shown to transmit disease, the bites can cause allergic reactions, swelling, rashes, and secondary infections from scratching. The blood loss from an infestation can be severe enough to cause anemia, particularly in children and people in poor health. The sleep loss and emotional distress alone are enough to bring on serious psychological problems.

A bed bug can survive up to a year without feeding. In the wild it might live in a nest or cave alongside its prey; in the city it prefers upholstery, loose wallpaper, or the dry, dark spaces behind pictures or inside light sockets. The worst outbreaks may be accompanied by streaks of feces along the tufts of upholstery. A strange sweet odor that comes from the bug’s scent glands pervades homes with large populations of the bugs. The compounds it produces, hexanol and octenol, are used to communicate with other bed bugs, but the smell is a giveaway that trained dogs can detect even when people can’t. It’s been described as smelling like coriander–and in fact the name coriander comes from the word koris, which is Greek for bug. For the most part, these wicked bugs don’t travel around with people, although homeless people who don’t change clothes often may find that bed bugs follow them everywhere, laying eggs inside clothing or even under overgrown toenails.

Controlling bed bugs is not easy, especially in apartment buildings, where they can move from one room to another via ductwork or cracks in the plaster. City dwellers are starting to avoid purchasing used furniture for fear of unwanted hitchhikers, and mattress companies have learned the hard way that using the same truck to haul away old mattresses and deliver new ones can perpetuate the very infestations that people are trying to eliminate.

One promising new control is an old-fashioned desiccant dust, messy but nontoxic, mixed with the bugs’ own pheromones. This so-called alarm pheromone entices them to get up and move around, exposing them to enough of the desiccant to cause them to simply dry up and die. An even more natural form of pest control may show up all by itself: the house centipede, Scutigera coleoptrata, feeds on bed bugs, as does the so-called masked hunter, Reduvius personatus, an assassin bug that gets its blood meal by robbing bed bugs of theirs.

Meet the Relatives: The Cimicidae family includes not only bed bugs, but bat bugs and bird bugs as well; all depend on the blood of their prey for survival.

Brown Recluse (Loxosceles reclusa)

Size: Up to 9.5 mm
Family: Sicariidae
Habitat: Dry, sheltered, undisturbed places like woodpiles, sheds, and undergrowth
Distribution: Central and southern United States

(See the Image Gallery for an illustrated image of the wicked brown recluse.)

Ah, the poor, misunderstood brown recluse. This unassuming spider gets blamed for every kind of pustule, boil, and eruption that might afflict a person. According to reports in medical journals, the brown recluse has been held responsible for staphylococcus infections, herpes, shingles, lymphoma, diabetes-related ulcers, chemical burns, and even allergic reactions to prescription medications. Arachnologists insist that there are only two ways to accurately diagnose a brown recluse bite: to either capture the spider in the act and get it identified or have a dermatologist biopsy a fresh bite wound. Without that evidence, it is entirely likely that the painful, rotting lesion that sends a person running to the doctor was caused by something other than this dreaded spider–and the misdiagnosis is often more deadly than the spider bite itself.

That’s not to say that the brown recluse doesn’t bite, or that its bite isn’t painful. A severe brown recluse bite manifests itself as a nasty, swollen skin ulcer with dead tissue in the center. These bites form a red, white, and blue bulls-eye pattern, with a painful red area around the edge, then a white circle where blood flow is restricted, then a bluish-gray spot in the center that represents dying flesh. Contrary to rumors, most people recover from these wounds quickly, with only the more severe cases lasting a month or two. While there have been news reports of deaths caused by brown recluse bites, these accounts are disputed by some of the nation’s leading brown recluse experts.

What accounts for the number of misdiagnosed brown recluse bites? The spider itself was virtually unknown until the second half of the twentieth century, when a handful of news accounts placed the blame for mysterious wounds with this little-known spider. Now it seems that every person with an unexplained sore is able to find a small brown spider nearby. The brown recluse is easily confused with other species: similar arachnids resemble it and several even have the same violin-shaped marking on the back. The only way to accurately identify a brown recluse is to look deep into its eyes: they have six of them, arranged in three pairs. Experts also look for a uniformly brown abdomen covered in fine hairs; brown, smooth legs; and a small size (the body no more than nine and a half millimeters long).

Spiders in the genus Loxosceles are found in central and southern areas of the United States, but reports of their bites persist nationwide. To date, L. recluse has only been positively identified in sixteen states: Texas, Oklahoma, Kansas, Missouri, Arkansas, Louisiana, Mississippi, Alabama, Tennessee, Kentucky, and parts of neighboring states, including Nebraska, Iowa, Illinois, Indiana, Ohio, and Georgia. A few other species, including L. deserta, arizonica, apachea, blanda, and devia, have been found along the Mexico border through Texas, New Mexico, Arizona, and inland portions of southern California, but none of these are the true brown recluse.

Reports of the spider in other parts of the country are so persistent that frustrated arachnologists have offered rewards to anyone who could send them an actual brown recluse from an area where they are not known to live. One California scientist called it the “Show Me the Spider” challenge. After years of attempting to locate a brown recluse in the state, University of California entomologists have declared that the brown recluse definitively does not live in California.

For people who do live in places where the spider is found, it can be disturbing to realize how many of them live nearby. A family in Kansas collected over two thousand brown recluse spiders in and around their home in just six months. Remarkably, no one was bitten in the six years they lived in the house. A recluse usually won’t bite unless it is quite literally forced against the skin. For this reason, the best advice experts can offer is to shake out camping gear, as well as bedding or clothing that’s been in storage or crumpled on the floor for a long period of time. Avoid the recluse, they say, and the recluse will avoid you.

Meet the Relatives: Recluse spiders are related to another genus of six-eyed spiders called the six-eyed sand spider. These spiders are known for their necrotic venom.

Chigger Mite (Leptotrombidium sp.)

Size: 0.4 mm
Family: Trombiculidae
Habitat: Low-lying, damp grasslands and woodlands
Distribution: Throughout Asia and Australia

(See the Image Gallery for an illustrated image of wicked chigger mites.)

Soldiers fighting in World War II had to face down more than the enemy. In Burma, monsoon weather, unfamiliar terrain, and exotic diseases made for a deadly combination. Virtually every soldier in the area was hospitalized at some point during 1944. Although combat was heavy, soldiers were nineteen times more likely to die from disease than from battle wounds. Hepatitis, malaria, dysentery, and venereal diseases posed serious problems, but perhaps the most challenging disease was the unfamiliar and unpredictable scrub typhus, transmitted by a tiny arachnid known as a chigger mite.

The chigger, actually the larval form of a mite in the genus Leptotrombidium, is a minute creature that feeds on blood only once in its life. It is so small that its mouth can’t even penetrate the skin deeply enough to hit a blood vessel; for this reason it simply bites into the skin and drinks down a kind of liquefied beverage of skin tissue and blood. A person might not even feel the bite until later, when a little redness develops at the site. This is usually caused by the chigger leaving its feeding tube behind, which can irritate the skin the way a tiny splinter would. Once the chigger has enjoyed its one and only blood meal, it matures into an adult mite and feeds only on plants for the rest of its life.

How, then, is the chigger mite able to transmit disease? If it only feeds once, there is no opportunity to take up the infection from one host and pass it on to another. Scientists solved this mystery when they were able to prove in the laboratory that these mites are capable of transovarial transmission. In other words, adult chiggers who get infected during their one blood meal then pass the infection on to their offspring. For that reason, a young chigger might already be infected from birth, and pass the infection on when it takes its first and only blood meal.

Scrub typhus, also called tsutsugamushi fever, is found in populations of wild rats, voles, mice, birds, and also in humans. People who have been infected with the Orientia tsutsugamushi bacteria usually experience flu-like symptoms after about ten days, including muscle aches, swollen lymph nodes, fever, and loss of appetite. Eventually, the disease can move into the heart, lungs, and kidneys, resulting in death if antibiotics and other life-saving treatments are not administered in time. Up to a third of people who don’t get treatment will die from the disease.

During World War II, scrub typhus was frustratingly hard to avoid. The mites lived in tall kunai grass, which grows to ten to twenty feet, and soldiers had no choice but to march through it. Burning down the fields of grass might have eliminated the mites, but this wasn’t always feasible in a war zone. The clothing the soldiers wore could hardly be sealed tightly enough to keep these tiny mites away. Soldiers who came down with the disease lost, on average, a hundred days of combat duty, as compared to only fourteen days for malaria cases. Twenty percent of them developed pneumonia, and one Army medical expert who treated the disease predicted that all of his patients infected with scrub typhus would live with permanent heart damage.

Today scrub typhus infections still occur in parts of Australia, Japan, China, Southeast Asia, the Pacific Islands, and Sri Lanka. There is no vaccine available, and over a million people are infected worldwide.

Meet the Relatives: Members of this family include harvest mites and other tiny bloodsucking creatures. The larvae of many species of mites may be referred to as chiggers, but the so-called chiggers found in the United States are usually young harvest mites that do not transmit disease.

Mosquito (Anopheles sp.)

Size: Wing length 3 mm
Family: Culicidae
Habitat: Varies widely, but usually found around bodies of water, from lakes to marshes to isolated pools
Distribution: Found in tropical, subtropical, and some temperate climates worldwide

(See the Image Gallery for an illustrated image of the wicked mosquito.)

On July 10, 1783, just as the Revolutionary War was coming to an end, George Washington wrote to his nephew that “Mrs. Washington has had three of the Ague & fever & is much with it–the better, having prevented the fit yesterday by a plentiful application of the Bark–she is too indisposed to write to you.”

The “Ague & fever” that the future first president of the United States was referring to was malaria, a disease that had plagued him since he was a teenager and also infected his wife. He suffered several bouts of it over the years, along with smallpox, typhoid fever, pneumonia, and influenza. And although the treatment for malaria–quinine, extracted from the bark of the South American cinchona tree–was already in use in Europe, the Washingtons did not have access to it until later in life. Unfortunately, the president took so much of the drug that it caused severe hearing loss during the second year of his term–a known side effect of quinine toxicity.

Malaria has been called our forever enemy because it pre-dates humans, as demonstrated by tests on mosquitoes preserved in amber from thirty million years ago. The earliest medical texts made reference to a malarial fever, and some even suggested that an insect bite could be the cause. But the word malaria, from the Italian word for “bad air,” suggests the commonly held belief that malaria was simply present in the air.

As we now know, mosquitoes are to blame. They transmit not just malaria but dengue fever, yellow fever, Rift Valley fever, and about a hundred other human diseases. Roughly one in five of all insect-transmitted diseases come from mosquitoes, making them the world’s most deadly insect. Malaria is believed to have killed more people than all wars combined.

Malaria is caused by a parasite in the genus Plasmodium. Female mosquitoes, not males, feed on blood. They must first become infected themselves by feeding on a host and taking up both male and female plasmodia, which then reproduce in the mosquito’s body and make their way to the salivary glands. Because mosquitoes live only a few weeks, they may not survive long enough for this to happen. But if it does, and they then feed on someone else, the disease cycle continues. They inject saliva into their victim, where it acts as an anticoagulant. If enough parasites are present in the mosquito’s saliva, the victim may become infected — but it is possible to be bitten by an infected mosquito and not get malaria.

Mosquitoes are attracted to their hosts by carbon dioxide, lactic acid, and octenol, components found in human sweat and breath. They also sense heat and humidity around a body. They like dark colors, and they seem to be drawn to people who have been exercising. A French research team recently discovered that mosquitoes are more attracted to beer drinkers. In Rangoon, Myanmar, residents can get as many as eighty thousand bites per year. In northern Canada, when mosquito populations are high, people can get bitten as many as 280 to 300 times per minute. At this rate, it would take only ninety minutes to drain half the blood from a human body.

Today 41 percent of the world’s population lives in an area where malaria can be caught. There are nearly five hundred million cases worldwide, and every year over one million people die, most of them young children in sub-Saharan Africa. Experts estimate that controlling malaria worldwide would cost $3 billion. Bed nets play a critical role in protecting people at night when mosquitoes are active, and prophylactic drugs like quinine are also an important strategy in preventing the disease. Currently there is no vaccine.

Malaria did have a brief starring role as a possible treatment for another disease. In 1927 Julius Wagner-Jauregg won the Nobel Prize for coming up with the idea of therapeutic malaria, the practice of deliberately infecting a patient with malaria to cause a fever high enough to kill some infections. He used this technique on late-stage syphilis patients. Once they were cured of syphilis, he administered quinine to treat the malaria. Fortunately, penicillin came along by the 1940s, putting an end to what must have been a miserable way to fight disease.

Meet the Relatives: All mosquitoes are found in the family Culicidae. There are roughly 3,000 species, 150 of which live in North America.

This excerpt has been reprinted with permission from Wicked Bugs, published by Algonquin Books of Chapel Hill, 2011.

  • Published on May 24, 2012
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