I've Got You Under My Skin

During the past three decades our family has given bed and board to black bears, coatimundis, raccoon, squirrels, skunks, foxes, ferrets, woodchucks, spider monkeys, marmosets, mice, rats, guinea pigs, and more dogs and cats than anyone should remember. These creatures had one thing in common—fleas. In theory it is possible to have pets and not have fleas, but long experience indicates otherwise. There must be trillions of fleas hopping about the world. An entomologist once estimated there were 500,000 in a pigpen he was observing. This says a lot about fleas and the enthusiasms of entomologists.

Whatever their numbers, there are enough fleas to distract every warm-blooded nest-building animal in the world. (Most pettable creatures are nest builders or descended from nest builders. If your choice in animal companions runs to sheep, elephant seals, horses or ostriches, you should not be troubled by fleas.)

Despite the infinity of fleas, a good many people who keep pets are loud in claiming that none of their charges ever have or will have them. They are like parents claiming that their children do not have cavities or watch trashy TV. It seems that having fleas, like having crab-grass or ring-around-the-collar, is a sure sign of moral turpitude. Only the slovenly are supposed to be plagued by these insects. In practice, things are not so simple. Fending off fleas for any length of time requires not just ordinary orderliness but superhuman fastidiousness. Anyone who thinks that fleas only infest slobs is overrating human abilities and badly underrating those of fleas. Not only do these little beasts wildly outnumber all pets and pet owners but they also have developed sophisticated equipment and tricky moves.

All of which may serve as background for a domestic scene that occurred one brisk winter morning in our house in Fairfield, Pa. A cat having been heaved out the kitchen door for making tracks through the butter, the family's attention turned to a gravid golden retriever bitch making a considerable racket under the table. She was vigorously scratching and snuffling at her flank. As she squirmed around she was noisily mulching the morning paper on which she was lying.

"If we've got them now, we are really going to have a flea season this summer," I said. (Had I known then what I do now, I would have opened the conversation with more class by casually quoting an old English proverb: "If you kill one flea in March you will kill a hundred.")

"I wonder what all the little fleas are doing?" my wife asked pensively.

"What do you mean?"

"I mean we almost always have them, but we are not really acquainted. I wonder how they spend their time."

It was one of those questions that grows more substantial the longer it is considered. One thing fleas have been doing for a long time (at least 120 million years—a fossilized flea unearthed in Coonwarra, Australia a decade ago was 120 million years old) is spreading out and diversifying. To what extent seems to be a matter of dispute among authorities. A British Museum report (1958) and the Encyclopedia Britannica claim there are 1,600 species of fleas. Hokes in Fleas (1974) says there are 2,000 species and the Encyclopedia Americana 11,000 species. In any event, there are enough fleas to go around, and they have done just that. Like many of us, fleas prefer a temperate climate, but in pursuit of what might be called business interests, i.e., warm blood, they have become global. They are now found from the deserts of the Sahara to the polar tundra and virtually everywhere in between.

Fleas belong to an order of insects called Siphonaptera, which, roughly translated from the Greek, means "wingless siphon." This is a good description of your basic flea. Nearly all adult fleas (there are no babies; fleas hatch full grown) feed exclusively on warm blood. They do so by drilling their siphons (sharp, flexible but toothless mouthparts) into the skin of their victims. The blood is sucked up into the pharynx by pumps and eventually reaches the stomach, which is a complex, compartmentalized organ equipped with a bunch of ingenious tubes and valves.