I can't imagine why, but a small genre of literary entomology really exists. St. Jerome wrote about beekeeping, as did the ancients, as did Maeterlinck in The Life of the Bee more than a hundred years ago. Maeterlinck's work stands as a classic, Victorian in its sensibilities, lyrical in its prose (the chapter on the mating flight is one long paean to the nobility of the sex act, worthy of Byron), and massive in its treatment. Otto Zinsser's Rats, Lice, and History some years later took a wry look at the brown rat, which, after it invaded Europe from the East and joined with the common resident louse, brought the terrible Plagues that shaped the course of the late Middle Ages. The past couple of years has seen, one could almost say, a mild infestation of new books about various six-legged critters. Most notable of these is The Ants, a comprehensive treatment of animals that most of us find unpleasant but they find fascinating, by Bert Holldobler and Edmund O. Wilson, and Martin Brookes' Fly, which pays tribute to the fruit fly's crucial role in the march of twentieth-century genetics.
And now we have another popular entomological treatise, Mosquito, by tropical disease authority Andrew Spielman, and a Pulitzer-Prize journalist Michael D'Antonio. Together they give us an intriguing look at the biology of mosquitoes and their considerable impact on human history.
Mosquito-borne diseases, we learn, ultimately defeated the barbarian invaders of Rome through malaria. Later, however, the same disease wiped out forty thousand Roman soldiers in, of all places, Scotland. Mosquitoes gave the U.S the opportunity to build the Panama Canal after French canal-builders were almost completely destroyed by yellow fever. Malaria helped us beat the Japanese in the Pacific, when our medicine proved more effective than their medicine. "No animal on earth," say the authors, "has touuched so directly and profoundly the lives of so many human beings." That is saying a great deal, if one considers the contributions of dogs and horses and possibly herring, but they offer plenty of evidence to support the contention.
We learn, too, everything about the habits and appetites of some of the more than twenty-five hundred species of mosquitoes. They begin life as wriggling larvae in almost any kind of water, fresh or brackish, clean or filthy, depending on species. Some hatch their eggs at the margins of ponds, but others prefer discarded tires, broken flower pots, footprints of larger beasts that have filled with rainwater. The larvae hang upside down, breathing though straw-like appendages stuck into their backsides. The adults that emerge in a few days busy themselves almost entirely with the process of reproduction.
As part of that process for most species, we all know, the female needs to find a blood meal by which she can nourish her eggs. The males don't participate in this vampirish practice, so don't blame them, although a few species do harbor aberrant males, called gymnandromorphs, who drink blood even though they have no use for it. The males are generally, in fact, so tiny and insignificant that you have probably never seen one. All they do is gather in a cloud of their fellows and wait for the females to show up. Their compensation for reduced prominence may be that they get to mate several times, while the female, who receives a lifetime sperm supply in the first try, is through with romance and has to content herself with drinking blood and laying her eggs. The authors refer to her experience as "a single minute or so of passion."
It is the bite of the female that has caused so much grief for human beings. As she drinks, she is introducing her own disease organisms into the bloodstream of her victim. When she is finished, so bloated that she almost cannot fly, some species must rest and eliminate the water from the blood (it is while resting, say on a wall, that residual insecticide is likely to do her in). The nutritious dehydrate that is left will fuel the next generation.
What they leave behind include some of the most debilitating diseases in human history: malaria, yellow fever, dengue, and various forms of encephalitis. The part mosquitoes play in these scourges was not understood until long after microscopes revealed that the illness were caused by microorganisms; malaria, after all, is Italian for "bad air," a term that expresses the old belief that it was foul-smelling misasmas that led to its onset. Actually the first disease firmly connected to mosquitoes as vectors was not one of the major ones but elephantiasis, a horrid, relatively rare African malady that make the legs or the testicles swell to gigantic size.
The last part of the book recounts the spread of mosquitoes around the world and the efforts, some heroic, some wrong-headed, mostly frustrating, to eradicate them from populated areas. Yellow fever, for example, moved in slave ships from Africa to the New World, where it repaid the Europeans' dubious gift of civilization with continual epidemics all over the two continents. And mosquito-borne disease was not exclusively a problem only in the tropics. In 1790, ten percent of the citizens of Philadelphia died in a single summer from a plague of yellow fever. Malaria brought the urban development of Staten Island in New York to a standstill. New Orleans in 1853 was so overwhelmed by malaria that: "Coffins piled up in the delta heat, and the swelling bodies burst their coffins. Desperate city officials burned barrels of tar on street corners and fired off cannons at dawn and dusk in an attempt to 'cleanse' the air."
At the beginning of the twentieth century, several developments gave hope that the mosquito could be eliminated as a vector of disease. First, the sanitarians, public officials who were convinced that these diseases could be controlled only by strict elimination of the mosquitoes' breeding grounds, began to gain acceptance, funding, and authority for their programs. Junkyards were emptied, pond surfaces were covered with oil, and in some cases even private homes were invaded by inspectors who looked for the smallest bit of standing water. Also, better treatment of affected patients reduced the prevalence of the microorganisms available. Quinine is the oldest remedy and still one of the most effective, but more sophisticated drugs, some herbal, some systhesized, have come along. Increasing use of screening has further reduced exposure to the parasites. Finally, The widespread use of DDT dramatically reduced the number of cases of all insect-borne diseases.
At first it all seemed to be working. But soon both mosquitoes and the disease organisms themselves proved highly adaptable, developing resistance to both the drugs and the insecticides. And as the number of infected persons decreased, the natural immunity in the native populations dwindled, so when a rebound occurred there was less of an immunological defense. Finally, as the dangerous effects of wholesale spraying became apparent, especially through Rachel Carson's Silent Spring, governments were less willing to engage in such programs. By 1967 the World Health Organization officially declared the eradication of the mosquito a failure.
Now, it is estimated, ten percent of the world population suffers from malaria, and every twelve seconds a child dies of it. Closer to home, the outbreak in and around New York City of West Nile Virus, a form of encephalitis, shows that the resourceful mosquito can survive and even extend his destruction in the face of the best that science can do. As the authors say, "Mosquitoes were here on earth before us and will likely survive us."