A Most Dangerous Creature

A Most Dangerous Creature

If you were asked to envision the world's most dangerous creature, what would come to mind? Doubtless something huge and scaly with claws glistening, fangs bared, and hoofs flailing; with horns, stingers, world—class poisons, or other built—in weaponry; and sporting an impenetrable armored coat.

Most of these features are absolutely unnecessary, for an animal equipped with neither weapons nor defenses is, if not the champion, at least among the front—runners of creatures that plague humankind—Musca domestica, the lowly housefly.

The fly, worldwide except in the Antarctic, is of all animals consistently the most dangerous to man. The diseases it transmits bring more misery and death to humans than could any imaginary monster. Having selected humans as its permanent companion, the fly carries over 30 different serious diseases to people all over the world: typhoid, tapeworm, hookworm, whipworm, yaws, diarrhea, amoebic dysentery, tuberculosis, ophthalmia, trachoma, septicemia, gangrene, conjunctivitis, or any disease caused by the millions of bacteria the housefly can carry around on its body and legs.

The fly's body structure and lifestyle guarantee a ready supply of disease—producing bacteria to redistribute among its human companions. Almost constantly on the move, the fly travels many miles in its 30—day adult life. During its short, active life span the fly, attracted to aromatic garbage, decaying bodies, and manure, constantly picks up microorganisms on its hairy body and sticky footpads. Then it hurries off to the equally fragrant food preparation and serving quarters of humans. The average fly carries about 1,941,000 bacteria on its body in clean communities, 3,686,000 in areas without sanitation. Most insect larvae compensate for the destructive activities of the adults, but not the housefly. Rather than hastening the disintegration of the waste matter on which they live, the larvae devour the organisms that break down refuse and retard the process of decay.

A "fly fact" even more horrific is their incredible rate of reproduction. A female housefly lays several hundred eggs, which hatch in 8—12 hours into maggots that become pupae and then a new crop of adult flies within a week or two. If the eggs of just one fly and all those of her offspring were allowed to hatch and grow with no casualties, the result would be, in about six months, over 5.5 trillion flies! They collectively would weigh over 80,000 tons and would carpet the earth to a depth of three and one—quarter feet. The meek would truly inherit the earth. Mercifully for the earth's inhabitants, only an infinitesimal number of fly offspring make it to adulthood.

As a result of the fly's prolific reproduction and short life span, its evolution is speeded up enormously. Within a few generations the fly develops immunity to almost every type of insecticide. This immunity is complete within a year or two. Attempts to control or wipe out the housefly with chemicals would poison much of the surrounding environment (as did ddt) before they could even make a dent in the fly population. Therefore, control of houseflies is best achieved by depriving them of breeding places. Although there is no way to control and remove all decaying organic matter, we have the power to control access to our food and cover and make inaccessible the garbage generated by humans.

The fly does have an enemy. Eupusa muscae is a relative of the common black mold found on bread (dead organic matter). Because Eupusa muscae feeds exclusively on living flies, it is a major agent in fly population control. Every year millions of flies worldwide become infected by the parasite and almost always perish before adding to the fly population.

But humans continue to try to control the flies that annoy them personally. The weapon of choice is the daily newspaper, a method less than 10 percent successful. The fly's ability to escape impending newspapers is not supernatural; it results from the fly's physical makeup. The hundreds of hairs that cover its body (and help it carry diseases hither and yon) are also its defense mechanism, for they are very sensitive to air pressure. Movements of a hand, a descending newspaper, or for that matter any solid object will create air fluctuation. The fly, warned of approaching trouble, escapes in less than an eye blink.

An effective weapon would need to have numerous holes through which air could freely pass. Such an ingenious invention, developed many years ago, is the flyswatter. It can descend on its victim with no air displacement, so the fly is cornered and squashed before it can figure out what has just happened. SWAT! One fly down—only 5,499,999,999,999 to go!


From the book: 
Petrified Lightning