The man who watches fleas at the San Diego Zoo

Billions of the suckers

Molly, my friend Jerry's cocker spaniel, met me on the patio. Blond Molly wagged her stub of a tail, jumped up, danced, rolled onto her back. I petted her warm stomach. She turned to her side and fell asleep splayed out on the cool bricks. As Jerry and I talked, a flea crawled out of wispy hairs along Molly's inner thigh, climbed her sloping belly, passed over a pink teat, then disappeared into thick curls covering Molly's rear.

I knew vaguely, that the flea was a parasite. I knew, too, that a parasite is an organism that grows, feeds, and is sheltered on or in a different organism while contributing nothing to the survival of its host.

"To that flea," I said to Jerry, who had observed the insect's journey, "Molly's body is the world itself!" Jerry — Molly up and wagging, trotting behind him- was heading indoors, to draw water for a flea dipping. So I was left alone, on the flower-upholstered chaise, wondering about fleas.

At the San Diego Zoo one cloudless morning, I found county pest control technician Paul Damos, a burly man of Greek and Mexican descent. "All about fleas," I said to Damos, "I want to learn all about fleas."

Had I come to ask advice about killing fleas, he couldn't help. Damos, a county employee, assigned for the past two years to the zoo, said the county didn't like its pest control technicians to give recommendations for getting rid of fleas but preferred that technicians talk in generalities about pest control. ""Somewhat like a politician,"" he grinned.

When I assured Damos it was the flea itself - its evolution, structure, life cycle, habits — about which I'd come to ask, he suggested we walk to the zoo employee cafeteria for coffee. But — he stopped in his tracks, and while zoo visitors swarmed about us, he demurred again — he was no flea expert. Fleas were only one part of a comprehensive pest-control program for which he was responsible at the zoo; he also battles vermin, mosquitos, and bees.

The flea, said Damos, brown eyes opening wide above his coffee cup, eats blood. Protruding from the flea's head are specialized mouth parts, stiletto-like proboscises - feeding and sucking tubes — the ""siphons"" of Siphonaptera, the scientific order to which fleas belong. Readying to feed on its warm blooded prey, the flea digs its claws into its host's skin. Using its mouth parts rather like a jackhammer operator breaking up concrete, the flea breaks open the skin and plunges its feeding-sucking siphon deep into its host. Once the siphon is anchored, the flea injects into its host a saliva rich in anti-coagulant. (This saliva often irritates the host's skin and causes itching.) At this point, the flea's gullet dilates, and the flea begins sucking upward the blood meal.

How much blood? “Just enough to fill itself. Not even a drop. Of course, what you worry about are young animals. If too many fleas get on a young animal — and this has happened in zoos — the animal can become anemic, even die. The Los Angeles Zoo lost a snow leopard. They felt perhaps fleas had been the problem.

Fortunately, we've never had any serious problem here with fleas. The animals — bush dogs, wolf, Scottish wildcat, some of the big cats — that keepers are concerned about, with fleas, are closely monitored.""

A zoo's flea troubles, suggested Damos, are somewhat different from those of pets in homes. "How are you going to check a lion for fleas?" he asked. "You have to wait until it is anesthetized in the hospital."

A zoo keeper excused himself for breaking into our conversation and asked Damos if he'd drop by later to check on a swarm of bees. He would, promised Damos, he would.

Returning to the flea, he said admiringly, "The flea is a tough little insect, well designed." As do most highly advanced insects, a flea undergoes complete metamorphosis. Four distinct stages make up the flea's life cycle: egg, larva, pupa, adult. At any given time, all four stages may be present in animal burrows and pet owners' homes.

"The egg is very small,"" Damos put thumb and forefinger together, allowing a scintilla of space between, "about half a millimeter long, white like a ping-pong ball. You can sometimes see the eggs. If the animal has a lot of hair, eggs may stay on the host, but usually eggs roll off, into the nest or a pet's bed or your rug. Depending on humidity and temperature, the eggs take two days to two weeks to hatch. If temperatures are low, the eggs take longer."

What emerges from the egg, said Damos, is the larva; grub-like, grayish in color; one-eighth to one-quarter of an inch long; visible to the naked eye. It is eyeless, legless, and propels itself by a rolling motion. It lives in a host's burrow or pet's bedding, in between carpet tufts, in furniture, in dark corners of rooms.

Yes, said Damos, answering my question, the larva eats. It has chewing mouth parts. It eats hair, skin, and droppings from adult fleas. Important to the larva's diet is an element found in adult fleas' stool: undigested blood excreted during and after blood meals. The blood's iron is necessary for development of the cuticle that becomes shell in the flea's third, or pupal, stage.

With variations among species and conditions, the flea's larval stage may be as short as 15 or as long as 200 days. ""Without warmth and humidity,"" said Damos, ""the larva will die.""

If all goes well, the larva salivates a silky thread and spins around itself a U-shaped cocoon. Shrouded by this cocoon, the flea ""pupates"", just as a butterfly caterpillar will, or a beetle larva. "The pupa," said Damos, "starts off white, but gradually the white shell darkens as dust and dirt coat it."

Within its cocoon, the flea can remain alive and inactive as long as a year. However, in certain species under some conditions, this pupal stage may last only a few weeks. Whichever, when the pupal stage ends, the flea hops out as the fully formed adult we call a flea, the male generally smaller than the female. "When the flea emerges," said Damos, ""it's hungry. It goes — immediately — after a blood meal.""

Damos, who before he joined the county payroll worked for 13 years in commercial pest control in the Bay Area, said that it was at this point - when the flea emerged from its pupal stage — that a pest controller is often called. "A pet owner would have been away on vacation, had the pet in the kennel. The pet owner would come home, walk in the door, fleas would hop right on and start eating," Damos chuckled. ""The pet owner would say, 'My God, where are all those fleas coming from?'"

California, said Damos, has some of the nation's most stringent regulations for pesticide use. Here, all pest-control technicians must be licensed. As well, before these technicians can operate locally, San Diego County requires they pass tests on mosquito control and vertebrae and invertebrate vectors. Larger companies, such as Lloyd's and Terminix, who offer extermination services, train employees in pest identification and proper insecticide use.

When I asked Damos to tell me about the worst flea infestation he'd ever seen, he didn't pause to consider. "Definitely in San Francisco's Haight-Ashbury district, in an apartment building that had been a convent. Squatters had moved in. Animals had free access. An older lady, blind, living there, had a dozen cats. Or more. The cats were were in bad shape. And also living with her was a retarded girl. The girl's legs were covered with flea bites. That was a real bad case. I treated it twice."

Fleas, said Damos, his tone dolorous, aren't an easily defeated enemy. At the zoo, Damos battles fleas with organic phosphorus compounds applied in a fine spray into and around the animal's home. He also uses a chemical that attacks the flea in the larval stage, halting its development into a pupa. It does this by scrambling the larva's neural messages. The flea, Damos said with relish, then "short circuits" and does.

Insects are not the only pests Damos fights. He sets out traps for possum, skunk, raccoon, fox, rats. "Of rats, Rattus rattus is what we typically get here, a clean, very active animal, basically a vegetarian who likes fruit, nuts. Considering the zoo's size, Rattus rattus is not a big pest. Maybe in a week we get two or three."

In fact, said Damos, in his office on the zoo grounds he had several rats he'd picked up — in nonlethal HavaHeart gravity action traps — earlier that morning.

Why, I asked, didn't they use regular rat traps?

Standing, gathering our empty coffee cups, Damos explained that the state, as part of its plague surveillance program, sponsored a flea count program. Were the rats caught in the standard rat trap, they would die. "And as the rat's body temperature lowered, fleas would hop off the rat to look for a new ride. The flea's a parasite. If there's no meal there, there's no reason to stay. On dead rodents you can actually watch fleas leaving. If an animal's been dead for a while, you won't find a flea on it."

We slid up onto the seats of Damos's four-wheeled cart and headed onto the paths toward his office. Zipping up and down zoo driveways, Damos pointed out a spot at which he recently trapped a red fox. ""I've trapped five this year. They're basically nocturnal, get in here late at night. I suspect they come out of Florida Canyon. I find a lot of rabbits over by the train ride. Possums I get everywhere — the old jungle trail, the old reclamation pond."

The office in which Damos keeps his records was dark and cool. Three battered traps stood in one corner. Three rats skittered across the cages' metal floors.

Damos opened the bottom drawer of his desk and took out file folders. For each rat trapped on zoo grounds, he fills out a fact sheet — type of rat, sex, weight, place caught. Then the trapped rats are taken to the County Operations Center on Overland Avenue. Later, fleas will be taken from the rats and counted.

Admitting he didn't particularly like rats, Damos sat on his heels, peered down into cages. "These are Rattus rattus. One of these fellows can jump three feet off the ground, can run across a telephone wire, can jump across a four-foot-wide ditch, and they're excellent swimmers."

The largest of the rats, its tail behind it in a wide loop, gazed out toward us. "This is a mature rat, he's got brownish, grayish hair."

Sighing, Damos stood and brushed off his khaki trousers. Rats, he said, tend to have litters of five or six. He nodded toward the second and third cages. "These are younger rats, a bluish gray color, whitish on belly. As a rat gets older, it turns gray, and then when it's fully adult, turns brownish gray. We don't let them 'em live that long."

At the 115-year-old Natural History Museum, entomologist David Faulkner's second-floor windows look out over Balboa Park's treetops and beyond to Park Boulevard. Faulkner wore khaki trousers and a t-shirt commemorating the visit of China's pandas to the zoo. He folded his rangy frame into a chair at his desk. Sunlight sparkled on his glasses, picked out blond hairs in his mustache. Books and papers were stacked on heavy library tables. Across the room were glass cases in which were pinned specimen butterflies - birdwings, swallowtails.

Faulkner supervises and maintains the museum's entomology department, adding to and organizing collections, writing life-history studies of insects. As well, he answers questions about insects for the public. ""Basically,"" he said, ""I provide information on any aspect of anything having to do with entomology.""

Now in his late 30s, he received his doctorate in entomology from UCSB. About fleas, he rattled off basics. The flea. Approximately 2400 species or subspecies have been described. By comparison, mammal species number altogether some 5000. A parasite, the adult flea bedevils most mammals and some birds.

He then talked about parasitism. At least half the organisms on earth are parasites, living in or on another living organism, obtaining from it part or all of their organic nutriment. Faulkner hypothsized that the flea was initially a predator in rodent burrows, that the flea had, at that time, chewing mouth parts. It fed on what was in those burrows — plant material, fecal matter. At some point, perhaps the flea started biting the animal; then, eventually, the flea's chewing mouth parts evolved into the sucking siphon and the flea began to eat only the rodent blood.

Generally, primitive mammals will have primitive fleas, while youthful hosts, evolutionarily speaking, beat the most recently evolved fleas. Both host and parasite ascend the evolutionary tree together.

Over hundreds of thousands of years, ever more subtle specialized adaptations ended in certain fleas being able to sustain life on only one species of bird or mammal. The majority of extant fleas have carried parasitism to this extreme: they are host specific, able to live on only one species of mouse or rabbit or possum. If the host to such a parasite dies out, becomes extinct, the parasite — its fate ineluctably linked to that of its host — adapts or dies.

A fossil flea has been found dating from 12 million years ago. ""When you look at a flea, you're looking at an insect that has evolved over thousands and thousands of years. And the flea is no doubt still evolving.""

The aptera of Siphonaptera is Latin for "wingless." Most parasitic insects, said Faulkner, are wingless. "Lice — body lice, pubic lice, head lice — don't have wings. Fleas may have had wings in the past. Every insect somewhere along the line had wings."

Off the host, fleas get around ""by hopping from one animal to another. They have highly modified legs for hopping, jumping. Because many hosts to the various flea species are not animals who live communally, hopping may have tended to give fleas some advantage for survival."

Powerfully muscled legs and a propulsion apparatus in the legs allow the flea to leap enormous distances. The extraordinary leaping ability of fleas is made possible, in part, by the presence of a highly compressible rubber-like protein substance, resilin. It is resilin, and energy stored and then released in resilin membrane layers, that fuels the wing articulation of flying insects — that permits fleas to fly. It is also resilin, in part, that generates the energy for the jackhammer-like activity of the fleas proboscises.

If man could hop as well as a flea? "You could hop over a two-or three-story building," Faulkner said.

Fleas are found worldwide. (None, as far as Faulkner knew, exists in marine environments.) In this state alone, there are billions of individuals. "And in California, probably 30 to 40 species of flea exist that no one will ever see because they are on, say, some mole no one ever encounters."

In Balboa Park, on whom are fleas riding, feeding, breeding? "A lot of feral cats are living in the park now, and the zoo. There are also people who will have fleas on them from time to time. On birds, there will be stick fleas. The zoo, with its myriad exotic animals, offers fleas a smorgasbord." Faulkner laughed. "There, a flea encounters a variety of animals and perhaps would test out an animal with which they were unfamiliar. You know, 'Let's go try a gazelle.'"

In San Diego County, Faulkner cited two species of flea - dog and cat - as causing a problem on pets. Of those two, the cat flea proves most troublesome. ""Originally,"" said Faulkner, ""the cat flea was probably only on cats. When people started bringing together other domesticated animals - cows, donkeys, whatever — it gave the cat flea an opportunity to test out a buffet of hosts. Somewhere along the line you had a mutant flea who said, 'Hey, this isn't bad! I can survive on this.' His offspring carried on this trait. But originally, the cat flea was on cats and cats only."

Dog fleas are host specific. A dog flea stays on a dog. But cat fleas are not host specific; they will hop onto dogs and, once on a dog, may cause the animal much discomfort. Faulkner speculated that some dogs may be allergic to cat flea bites. ""Certainly, cats don't seem to have the problems with fleas that dogs do. A cat may have some flea bites here and there, but I don't see cats scratching like I see dogs do.""

A cat flea will also hop onto a human. "People go to the beach, get bitten, then say, 'These are sand fleas.' They are not sand fleas. They are usually cat fleas that happen to live on rodents that are in the rocks, like those between Cardiff and Solana Beach, or they are on pets that people bring to the beach. The pets go into the salt water, the fleas drop off and get into towels and blankets people brought with them. But what people have picked up are cat fleas. There is no such thing as a 'beach flea.'"

How, I wondered, did a flea know on what it had landed? ""The flea, like any other insect, picks up cues in the environment — hosts' odor and body heat, changes in light and shadow, traces of carbon dioxide exhalation.

"In general,"" Faulkner continued, warming to the subject, ""this is what happens: on the host, a flea picks up smells which indicate the flea can bite. As soon as the flea bites and blood starts flowing, the flea can ascertain what it's on. If it's the proper host, the flea will stay on. If it's improper, the flea will jump off, seek another host."

Most mating between fleas takes place on the host animal. ""One good thing about host specificity, you know where to meet friends! If you're specific on one animal, that's where you're going to run into everything that's feeding on that one animal. If you're a generalist, you've got a bit more of a problem, because you may not have a specific place where you meet your own kind. Once the flea jumps off the host animal, there's not anything that tells them, 'This is a good place to meet.'"

Faulkner's telephone rang. He excused himself, carried on a moment's conversation, then said good-bye and hung up the phone. The call was from a zoo keeper, wanting Faulkner to identify an insect on the eucalyptus in the koala exhibit.

Returning to his subject, Faulkner explained that most fleas display no apparent rhythm in breeding and egg-laying. But further study of fleas may elucidate as yet unrecognized patterns. One of the world's few flea experts, Miriam Rothschild, daughter of English banker/naturalist Nathaniel Charles Rothschild, has shown that the European rabbit flea is so specialized in its adaptation to its host that its very breeding cycle is keyed to that of the rabbit. This flea can breed only when its hostess is pregnant. Further, as time for the rabbit mother's accouchement nears, the rabbit flea moves to the mother's head. When the rabbit mother gives birth, the flea lays its eggs in the rabbit's nest, thus securing for flea children a new generation of rabbit hosts.

Some bird fleas will breed as soon as they shed their pupal cocoon and before siphoning up a blood meal. But in most flea species, shortly before or after obtaining the sperm, the female must take a meal of blood to furnish her eggs with the protein they need to develop.

"Mosquitos," said Faulkner, "can go through a number of generations in which the female has no blood meal and feeds only on nectar. In certain parts of Alaska, you look around for big vertebrates and you don't see any. But you get out of your vehicle and the mosquitos cover you. They are feeding on plants, on nectar. With a blood meal, the female mosquito could produce 300 or 400 eggs. With nectar, she may produce only 100, 150. But this ability to feed on nectar gets the mosquitos through, generation after generation."

Did fleas, I asked, serve any good purpose? Faulkner guessed that fleas who are plague vectors, carrying plague from sick to healthy rodents, might be helpful in keeping in line species that could be pests — rats, for instance. But in an urbanized society, Faulkner thought fleas were generally not good for much.

What are predators on the flea?

"Various species of mite and beetle will feed on all four stages of flea. Some species of mite live upon the adult flea. Bacteria and bacilli, most notably the plague bacillus, Yersinia pestis, infect fleas. And of course the grooming habits of the flea's host - scratching, biting — put the flea at risk."" In lab experiments, 50 adult fleas have been placed on white mice. After a week's time, as few as 14 fleas remain on the mouse. The fleas have been shaken off, crushed, bitten, swallowed.

Insects, Faulkner assured me, are very adaptive. ""They compensate, allow for a lot of mistakes. A female insect may deposit 500 eggs, but only two of them may get through....

"In biology, the general rule is: if you lose something you won't get it back. Most creatures are headed toward evolutionary dead ends when they get to a point at which they can't lose anything else. Because they can't gain anything. You have some generalized creature like a cockroach, which has more flexibility to lose things, to change, to modify, you will probably get things that will come out of cockroach stock and develop into niches that become available. Like parasitic cockroaches. Why not?"

Faulkner's speculation on roaches led me to ask, "When entomologists get together, do they ever conjecture about the nature of future insects?"

"Usually, after we've had drinks."

Then, quickly retracting his statement, he turned mock serious. ""No. Actually before the drinks start, that's a tendency."

Entomologists' talk, said Faulkner, tends not to look at the future as much as at the past. "The present is the future as far as we're concerned, because we're trying to determine what the primitive stock might have been. Once you get an indication of that and how it's changing, then you can look at the far future and say, 'This is what it could become.'"

As Faulkner and I parted, I asked if he knew where I might find a flea circus. He laughed, said he didn't. I mentioned that in the late '50s, photographer Diane Arbus was wont to take her Leica and go to New York City's Times Square to Hubert's Freak Museum and sit with Professor Leroy Heckler, operator of Hubert's flea circus, while Heckler, rolling up his sleeves, offered, as lunch, to his flea performers - human fleas - his bare arm.

"Lots of things,"" Faulkner told me, ""happen in New York."

In the basement of a building on Front Street, i proceeded haltingly through a maze of narrow hallways to find Theodore Smith, district public health biologist with the environmental management branch of the California Department of Health Services.

At the maze's end, Smith greeted me at the door to his windowless office/laboratory. For the district that encompasses San Diego and Imperial counties, Smith serves as consultant, training officer, and resource for local agencies and citizen groups. From Smith, I hoped to hear more about fleas, to learn what I could about plague (transmitting plague from rodent to man, the flea has caused more deaths than all the world's wars), and to find out what became, eventually, of Paul Damos's rats from the zoo.

Smith — mid-fiftyish, wearing shirt and slacks, his gray hair crew cut - was immediately genial. I noted, as he directed me to a chair at the corner of his desk, that he was troubled by a slight stiffness of gait.

He explained. Born in 1933 in Ventura. Graduated from college in Fresno. Trained as a wildlife biologist. Spent two years in Sequoia and Yosemite with the National Park Service. At 22, he fell off a cliff.

Smith winced. ""Just about everything was broken. I was out cold for three weeks. I spent two years in a cast. When I got out of the hospital, I started looking for something else to do. Over the years I picked up a master's degree in entomology, course work for degrees in entomology, microbiology, botany. Had a lot of fun doing it."" Smith patted his desk (on which stood framed wedding pictures of his three daughters). ""This work has been 33 years of fun.""

We toured his office and laboratory. On wooden counters, microscopes sat at the ready, as did Petri dishes and stacked watch glasses. Filing cabinets held mammal, flea, tick, and mosquito collection records. All around the walls, scientific texts spilled from metal floor-to-ceiling book cases. One shelf held Smith's science-fiction collection.

He suggested we go to the counter to look at a flea. Through the eyepiece, magnified 48 times, what I was seeing, said Smith, was the ground squirrel flea, "Diamanus montanus."

Was this the flea that lived on squirrels running across city parks? Yes, Smith said. "The ground squirrel is a neat animal for us to watch as an indicator of presence or absence of plague because it can be seen during work hours. Mice get infected with plague, but they are never out except at night, so the only way you can see them is to catch and test them. But with ground squirrels, if suddenly they weren't there, you'd know, 'Something's wrong.'"

Rust in color, the flea appeared "armor-plated"" Smith explained. The flea's skeleton, or, "exoskeleton," is on the outside — "exo," "outside." The flea's internal organs are within that exoskeleton.

Insect blood? I asked, gazing down at the flea Smith spoke of, familiarly and even affectionately, as "Diamanus." Insect blood is usually colorless and not confined to veins and arteries, but fills the entire body cavity. The heart is a long tube, and to it there are sometimes little accessory hearts at the bases of wings, legs, or antennae to pump blood to these narrow organs.

The flea appeared like a pincushion stuck with pins of varying lengths. ""pines, combs, and bristles," said Smith. These allow the flea to remain anchored to its host. These bristles tend to be highly individualized from flea species to species. This individualization reflects the flea's adaptive capacity, the molding effect on the flea of the host environment, for, in the case of fleas' spines, combs, and bristles there have occurred, over time, adaptations to "fit" the vestiture (fur, feathers, hair) of various hosts.

Specializations in these spines, combs, and bristles also will tend to reflect traits of the host and its environment — is the host nocturnal, arboreal, volant (flying)? A flea attached to a bat or bird must, for instance, be able to hold on more tightly than a flea attached to Rattus rattus.

Smith talked for a moment about the head, on which eye spots, antennae, and mouth are principal features. The antennae, acutely sensitive, pick up temperature changes and smells and are used to taste and feel. Many fleas have no eyespots and can be presumed blind. Those fleas with eyespots may be able to detect light variations or maybe not. He added, ""A good subject for a doctoral dissertation — or a career!""

Does the flea hear? "No," said Smith, "but the antennae of many insects serve as receptors to various conditions, perhaps including sound, or air vibration."

Diamanus's sharp proboscis angled sharply downward from its head. Smith described this swordlike mouth part as "a tiny hypodermic needle," adding, "I like that description."

How does the flea breathe? "In most insects,"" said Smith, "in the thorax and abdomen there are little holes that open and close and tubes that get smaller and smaller and ultimately lead to every cell in the body, just as does our blood system. Insects are getting oxygen not the way we do, from air to blood to cells, but directly from the air to the cells.""

The abdomen, said Smith, contains stomach and intestine, excretory organs and the reproductive system. "Intercourse? Just like we do. Except they do it backwards. The female has an ovipositor which she extrudes and the male then applies himself to her."

Looking up from Diamanus, I asked, ""What happens when more than one species of flea comes to live on the same host. Do they breed?"

"They can't breed," answered Smith, "but we don't know if they try each other out. Obviously, since we don't get intergrades, if two different species of flea are having sex, it is not successful biologically. And they don't get all that much fun out of it. It's over so quickly, the joy they would get out of it would be short-lived."

With that, we went to stand by a projector into whose carousel Smith had arranged public health service slides on plague. As he set out the screen, Smith sketched a brief description and history of bubonic plague — a contagious disease caused by bacteria typically transmitted by fleas from infected rats and characterized by chills, fever, vomiting, diarrhea, buboes, and malaise.

Black Death? "A form of plague caused by the bacillus Yersinia pestis, a pandemic throughout Europe and much of Asia during the 14th Century, killing one-fourth of the population of Europe."

The first slide showed a man identified only as "an Arizona cowboy." The cowboy's fingers and toes had turned to blackened, misshapen stubs. ""Grisly,"" allowed Smith, going on to explain that bubonic plague came to be called Black Death, because — just as I was seeing here — decomposed bacteria and blood cells turned the plague victim's skin black.

The cowboy, face gaunt, eyes husterless, glowed motionless on the screen above us as Smith talked. Y. pestis — plague — has been on Earth longer than man. All across the world there are plague foci, places in which the plague bacillus is endemic, living year round, century after century. Typically the bacillus is found in rodents.

Much about plague remains mysterious. ""We do know that the plague bacillus can last a long time without a host. That it appears to have a tendency to recur cyclically. That it is basically a disease of wild animals. That the major carrier of plague from wilderness to cities is the rat and its resident fleas.

"I wish we knew how plague was originally transmitted. We don't." Until the last years of the 19th Century, no one knew. Plague was blamed on what or whomever a plague-stricken society viewed as its enemy. Thus, variously, fingers were pointed at the devil, Jews, witches, the political opposition.

Plague broke out in China in 1855, then spread across the world. In 1894 in Hong Kong, a French doctor, Alexandre Yersin, first identified the plague bacillus. (Thus, Yersinia pestis.) In 1898, another French doctor, Paul Simond, became the first person to discover that the flea transmitted Y. pestis.

Simond observed rats. He noted that sick rats were more heavily flea-infested than were healthy rats. Soon after, Simond discovered that, contrary to then-current medical opinion, a rat flea would take its blood meal from man. Inspecting under his microscope fleas taken from plague-infected rats, Simond found in the fleas' digestive tracts organisms he identified as Y. pestis. He ground these fleas and injected them into mice. The mice died.

By 1914 scientists had traced the steps by which Y. pestis passes from unhealthy to healthy host. The process is complex, involving enzymes released by both flea and Y. pestis and, in the flea, a structure that blocks stomach contents from regurgitation back into the flea's mouth parts when siphoning begins.

Once in the flea's digestive tract, Y. pestis multiplies, doubling and redoubling, eventually blocking the gut. This causes the flea's blocking mechanism to function imperfectly, or fail, and Y. pestis to be regurgitated from the flea into the host on which the flea is trying to feed.

To make matters worse, a sick rat will most likely develop an elevated temperature — fever. It is assumed, said Smith, that this higher temperature will attract more fleas to a sick rat. Therefore, a rat with plague, as Simond observed in 1894, will tend to have many more fleas than normal, at a time when the concentration of Y. pestis in its blood is highest.

"When the host's skin is no longer moist and warm, the flea knows it's time to go. So, when the sick animal dies, a much larger number of fleas than usual are looking for a new home."

Two theories exist as to how plague came to California. Theory number one posits plague as present here for the last 10,000 to 12,000 years. This theory is based on discovery of drawings found in shallow caves near Mono Lake. These drawings, said Smith, portray ""stick people, hieroglyphics with what look like buboes under their arms. If these drawings do indeed show plague sufferers, plague might have come to California across the land bridge from Asia."

Theory number two posits plague as coming to California via ships carrying plague from Asia during the last years of the 19th Century. Infected rats got into San Francisco's Chinatown. In 1899 the autopsy of a Chinese man indicated the possibility of plague. The city fathers, concerned for commerce and shipping, denied, however, that plague was present, declaring instead that plague deaths were due to "syphilitic septicemia." Not until 1903 did the city of San Francisco and the state formally admit the presence of plague. Between 1900 and 1908 almost 200 people died of plague. In 1908, when a second plague outbreak occurred in San Francisco and the East Bay, five people died and plague entered the ground squirrel population.

Smith clicked the projector. Onto the screen emerged a scene in which three men stood in a clearing - tall evergreens behind them. The men leaned over a waist-high camp table. On the table were splayed out squirrel carcasses. Smith laughed. "Autopsies. I've seen my share of speckled livers and lungs and spleens. That's what you look for in bubonic plague. Yup, I've seen my share of those. Wind at your back, a pair of rubber gloves, an apron. We don't do that anymore."

In California, the last urban plague outbreak among humans occurred in Los Angeles in 1924 and 1925. California has an average of two cases of plague in humans per year, averaged out over the past ten years. In 1988 only one plague case was reported, a serviceman at Ft. Ord. Smith noted that it is believed the man contracted plague while sleeping out overnight near ground squirrel burrows. "Where squirrels had died. During a ground squirrel die-off, you will see fleas clustering around the mouths of the burrows. The fleas don't want to get out in the open where it is so dry. But they also want to get to a place where they stand a chance of running onto another host."

With fleas as vectors, the two diseases about which public health officers are most concerned are plague and typhus. To a lesser extent, added Smith, public health concerns itself with tularemia, a tick-borne plague-like disease first discovered in Tulare County. "Given rodents' efficiency for bringing plague into contact with man, if we know what's going on with the rodent population in regard to fleas and flea transfer in specific areas, were we to get a case of plague in a human, we could say, 'This is what happened, this is how to stop it,' rather than, 'Oh my God, what's going on here?' We don't want to be in that position." From the zoo, Paul Damos takes his trapped rats to the County Operations Center. (In San Diego County, there are five other pest-control technicians who also trap and deliver various mammals to the center.) Smith described the program's steps. "The rats are held there, live, until a tech has time to comb them. Before the rats are combed, they are anesthetized, usually with chloroform. You knock them out so you don't get scratched or bitten. Anesthetizing also knocks out the fleas.

"The tech then takes the rat out of the chamber and holds it over a white enamel pan. You then run the comb, backwards and forwards, through the hair."

Smith imitated the motion, and I interrupted to ask if he did this task. He smiled and noted that he'd done his share of rat-combing. "The technicians are getting very good at combing the rats."

He continued. "Then you look in the ears for fleas and ticks. And, for a good finale, you bang the rat sharply on the pan and you hope you have knocked off any fleas you haven't combed off!" The rats end up in a plastic bag, in the dumpster."

The fleas taken off rats are then counted. Smith slid his desk chair across the room to a table and produced from a stack of papers a form — "Mammal Collection and Ectoparasite Identification Record" — printed by the state health department. The form provided spaces for entering the host species, its sex, age, reproductive status, and a listing of names and numbers of parasites present on it.

One reason for this study is to find out what sort of a flea load we have — how many fleas we find per animal. Right now, on rats, the load is very low. We are getting an average of less than two fleas per rat.

"Ordinarily, in a plague situation the flea load would be far larger than normal. Say the normal flea load on a ground squirrel is 20 fleas. During an epidemic — an epizotic situation — the flea load might get to 200 per animal. If we had an unacceptable level, we would get out at once with an insecticidal dust and hit all the areas involved."

The county sends a copy of its flea count to Smith, who then compiles the data and sends it on to the state headquarters in Berkeley. The fleas, after being counted, go into saline solution and are kept refrigerated. Three or times a year, the fleas are sent to the state headquarters lab in Berkeley for identification. There, said Smith, state biologist Bernie Nelson "does the flea ID's."

Some 100 species of flea may be capable of plague transmission (and fewer than 20 of those species are likely to choose humans as a meal.) Fleas most often spoken of as plague vectors are the Oriental rat flea, Xenopsylla cheopis, and the northern rat flea, Nosophyllus fasciatus. Smith pronounced the Latin names with zest. "Human fleas — Pulex irritans — are very poor vectors; cat fleas — Ctenocephalides felis — so-so. The flea about which we really need to worry in Southern California is the northern rat flea."

Smith had recently given a lecture on plague at Kaiser. In humans, the initial symptoms of plague include fever, chills, headache, muscle aches, a feeling of weakness, and commonly, swollen and tender lymph nodes - "buboes." "If plague is caught early enough, antibiotics will cure it. But not penicillin, unfortunately. Someone goes to the doctor with a fever and bang! you get a shot of penicillin. But with plague, penicillin doesn't do a bit of good. You need tetracyclines or the good old sulfa drugs. And unless the doctor knows what he's dealing with — and most physicians have not seen plague — you could be in trouble."

It is possible to test for plague in the laboratory, but it is a lengthy process, much like that used by Paul Simond in 1894: healthy mice are injected with plague bacteria acquired by grinding plague-infected fleas. It is also possible to vaccinate against plague. But the consensus is that the vaccine is not entirely effective and lasts for less than a year.

"The worst possible scenario — fleawise — in the county? A lot of plague-infected northern rat fleas, because the northern rat flea goes quite nicely on our roof rats, and it also goes quite nicely on our ground squirrels."

But, added Smith, this has not happened. In Southern California, in 1975 and 1980, there were two apparent, but unproven, plague outbreaks among wild rodents. In 1987, a mountain lion caught in a trap was found to be infected with plague. "At the moment, we don't have any infestations in San Diego." Smith walked to his desk and knocked several times on its wood.

Terminix is a pest-control company with offices across the world. I'd picked up a copy of Terminix's pamphlet: "Residential Pest Control." Terminix professionals, the pamphlet promises, "control termites, insects, rodents."

Ron McEachern, technical specialist with Terminix International, greeted me in the company's Ruffin Road office. A heavyset man, neatly dressed in navy trousers and white shirt printed with "Terminix," immediately jovial in the way of men whose livelihood depends on public goodwill, McEachern ushered me into a meeting room and sat me in a chair at a long table.

He'd worked in pest control, he said, settling in opposite me, for 22 years. "I was at NASSCO when they had the big strike, I wasn't about to go unemployed for two years, so I got into this. It isn't as big paying as NASSCO and union, but it's year 'round."

He trains Terminix's 60 technicians and salesmen operating in seven branches from Palm Springs to Mexico's border. Training prepares employees for state licensing and license renewal exams. McEachern looked down and over the wire-rim glasses set on his nose. "You can't hire guys who got buried after high school. They have to be able to study." He laughed, showing gold teeth, and added, "They have to sit in a classroom and listen to me."

Tough laws protecting the environment, he explained, make necessary much of the training pest-control companies do. "We're not like a homeowner. He can buy pesticide and do what he wants. We're regulated by Consumer Affairs, pest-control boards. We've got the EPA, FEFRA. We've got to follow regulations."

"And there's no way to get total control of cat fleas. Ninety-two percent of all fleas are cat fleas. People pick up their cat. They see the cat's got fleas. They think it's the cat's fault. Well, it's not. If the cat's got a lot, it means the house has got more.

"The problem is, we get called in after the problem is there. If we could get in a home in March and April with Precor, and the adulticide, Safratin, then we could do something. The Precor gets the larva, breaks the life cycle. The Safratin gets the adult."

Tone again mournful (weary, like that of Paul Damos, and, I decided, the necessary sorrow of a man whose work remains never done), he continued. "But people don't normally call until it's too late. They call in summer. That's the worst time for us."

About 60 percent of cries to Terminix for help with fleas come from homeowners, and often the worst of these infestations occur in homes from which people had been absent for long periods. "Mother Nature is very smart," McEachern said. "If no warm-blooded host is around, the flea pupae will wait. The pupae just sit there in that empty house and then a warm-blooded person walks in the door. That adult flea emerges and hops right on. In Rancho Santa Fe where people have vacation homes, it's particularly bad."

For a moment, McEachern looked almost dreamy. "Ticks," he said, "are big time in Palm Springs. People open up vacation homes there and and they're attacked by ticks."

What happens after the homeowner calls? "We don't take the order on the phone and run out and start spraying. We don't do jobs until we've inspected and found what the problem is. We don't want to get under the gun by just spraying. The state can pull your license. It's never happened to us. But there have been criminal prosecutions for misapplying pesticides. We're gun-shy."

What about the exterminators themselves? How do they guard against fleas? "We make them wear rubber boots with insect repellent on them. Many years ago, it was common practice that if you got fleas on your legs, you turned the tank and sprayed your legs and pants to kill the fleas. Old-timers probably are doing the same thing."

Reminding me that "Precor gets the larva and Safratin gets the adult," McEachern said, "There's no way to kill the pupae. It's protected inside its cocoon. So it will hatch out to be an adult. But you've got that residual Safratin in the carpet for that adult flea. That will keep on killing up to 30 days under ideal laboratory conditions. Realistically, we look at 15 days, in the real world."

The cost for this, said McEachern, varies from home to home. Ballpark figure, he guessed, "Seventy-five bucks."

This flea control seemed so Sisyphean, so hopeless. Wasn't there anything a cat or dog owner could do to avoid flea infestations? Sure, said McEachern. "Bathe the dog regular. If you have a slight flea problem, a thorough vacuuming and go around the edges thoroughly and keep bedding washed and pet bathed, you'll keep the flea level down."

Before he became a specialist, McEachern had a regular route. Mission Hills to downtown, Little Italy north to Fashion Valley, from Hillcrest to Five Points. The night shift. Downtown. "Before Gaslamp was Gaslamp. A lot of hotels and restaurants. Two in the morning I'd go."

He recalled a downtown hotel with a grand staircase. "The minute you hit the front door, fleas would be on you, roaches. People living there were elderly, sick, and poor. Now, this hotel has been remodeled, sold for condominiums, big bucks."

McEachern reminisced about a job Terminix did in a downtown hotel being refurbished. "Rats," he said, "were running up and down in the hallways, everywhere. This was just two and one half years ago. Right here in San Diego. You think of Chicago, New York, Detroit as the places for that kind of thing. But it's like that here. You go into some of these basements downtown, there are some strange things going on down there. Lots of rats. Lots of Oriental and American cockroaches. People call 'em waterbugs to be polite, but they're roaches. And lots of 'em. You can see 'em when you flash your lights around. Like little tanks running across the floors."

How have flea-killing methods changed from the old days? "Well," he said, "20 years ago, when you used rodenticides that really killed rats, we had to dig holes six feet deep and bury him. Secondary kills, you kill the rat, the cat ate the rat, the cat died, it went up on the chain. Now, we used anti-coagulants, which just thins the blood and the rat dies of hemorrhaging, that's all it does."

Fifteen years ago, they sprayed yards with chlordane, which killed everything. "No more. The days of nuking a yard where nothing is going to live in it is long gone.

"They say chlorinated hydrocarbons will get into your liver and if you lose weight, the hydrocarbons'll get into your body. We have red counts taken, physicals, and we never had a problem. We still wore the rubber gloves, the respirators. Some guys wouldn't take precautions. It was an attitude of 'I'm tougher than this.' And that's the guys that had the problem. But the old guys I know, they're mostly still around.

"When you first are into it, you feel like the avenger. We get some guys, 19, 20 years old, and they put the respirator on and it's like they're talking to NASA. 'Here from flea control.' But after a while it turns into work. You get used to it, it's a job. You say," McEachern sighed, " 'Well, I'm going to go out 'n' kill my bugs.'"

McEachern stood from the table and hitched up his trousers. "You can't win. You put your little dent into it. That's why I've been in it 22 years. That's why I'll retire in it. Pass on my insects to somebody else.

"I was in the business when you could kill bugs. I was talking the other day to someone from Dow Chemical, I was saying to him, 'John, I could remember when I could kill bugs.' Now, it's 'controlling insects.' That's what we're doing."

Did he miss the good old days? "No, I don't. A lot of things were done in those days that weren't good. Oh, sure, we knew it. We didn't want to admit it to ourselves. The new laws and regulations have made us better technicians. Now, we're actually killing insects, instead of arbitrarily screwing up things. Nothing bad ever happened back then, but it was, I think, because God liked us."

At the zoo, Paul Damos had spoken reverently of Dr. Nelson, a parasitologist who heads California's plague-surveillance project and to whose Berkeley offices are sent fleas collected in San Diego. When I visited Ted Smith in his basement Front Street office, Smith several times, fondly, mentioned Bernie Nelson. A beaming Smith noted that so keen was Nelson at flea identification that he could toss a batch of dead fleas out onto white paper and, with his naked eye, identify the fleas as to species.

A seven-story building set at the edge of the University of California campus in Berkeley houses one of the eight branch offices of the state's Department of Health Services Environmental Management. In the reception area outside environmental management's warren of offices hung the same bright yellow, red-lettered sign seen in state campgrounds.

Plague Warning

Chipmunks, Ground Squirrels, or other wild rodents in this area may be infected with plague. Plague can be transmitted to human by the bite of an infected flea or by handling an infected animal....

The sign further warned:

Keep pets confined or on a leash. It is better to leave pets home. Do not camp, rest, or sleep near animal burrows. Avoid all contact with chipmunks, squirrels, or other wild animals. Do not touch sick or dead animals.

On a sunny chill morning, Nelson, wearing khakis and plaid shirt, greeted me in his small office. As carefully outfitted as a ship's cabin, not an inch of space wasted, bookcases were stacked with entomology and parasitology texts, microscopes sat on a table beneath the south window. Above Nelson's desk on a bulletin board was pinned a photograph of grande dame of fleas, Baroness Miriam Rothschild. (By the 1890s, only 70 species of flea had been described. It was at this time that the baroness's father, Nathaniel Charles Rothschild, began what would become the world's greatest flea collection. The baroness herself, although never formally trained, went on to become one of the world's leading flea experts.)

A blond, bearded Swede in his mid-40s, Nelson seemed shy, almost skittish. But as he talked about his work in plague surveillance, about fleas, he turned delightfully voluble. His eyes — an intense blue — sparkled. Nelson is one of 20 field biologists employed by the state. (He is also statewide consultant for identification and biology of ectoparasites.) Among field biologists' duties are surveillance and suppression of disease vectors.

Nelson identifies some 10,000 fleas a year. The fleas arrive in his office together with mammal-collection data sheets such as I had seen in Ted Smith's office. Each host has its own sheet. Noted on the sheet are the number of fleas found on the host.

Was it true that Nelson could identify many fleas by sight, without aid of microscope? Almost embarrassed, he admitted: "I know the fleas so well that I don't have to put each animal on a slide. Occasionally on white paper I can identify them. Some I have to transfer to a microscope."

He makes most flea identifications by viewing the mounted insect beneath the lens of the dissecting microscope. What he looks for are key characters that allow identification as to species. These characters include various spines and bristles, head shape, presence and absence of eyes, length of mouth parts, presence and absence of certain structures in genitalia of male and female.

Once the flea is identified, what does Nelson look for? "You sex it. You can roughly age a flea. But only within limits. Out of curiosity I will sometimes look for parasites, external and internal." Mites, for instance, will attach themselves to fleas. "The mites," said Nelson, "don't seem to do any harm to the flea. I know that in some cases the number found on an individual flea can be pretty heavy — often a flea will be carrying some 30 mites — so I imagine there's a weight factor!"

Each of the eight environmental management area offices has biologists that carry on routine plague surveillance programs or respond to evidence that plague may be present. If the fleas are taken as part of a plague surveillance program, Nelson identifies and catalogues them. He pointed to the stainless steel book shelf that reaches from his office floor to ceiling. "Those big ledger books are filled with flea identifications back to 1971. Fleas I've identified associated with plague surveillance."

Straggling, said Nelson, is one thing he looks for. (A ground squirrel flea found on any host other than the ground squirrel is said to have straggled.) Since plague is a disease of wild rodents, and domestic rodents are going to be infected with it by wild rodents, Nelson will be particularly watchful for domestic hosts carrying fleas normally found on wild hosts. For instance, in cities, ground squirrel and wood rat fleas found on domestic rodents would indicate that there had been a die-off or a commingling among domestic and wild rodents.

A recent study conducted by the state in Los Angeles had at its goal learning how many northern rat fleas each rat hosted and if a seasonal distribution of fleas existed on those rats. "We found there was a seasonal low in February, with virtually no fleas on the rat in that month. However, in late August and September, the rats had flea loads of up to 80 or more individuals per rat. The average over the year was between 16 and 18 fleas per rat.

"Based on work that was done, originally, in India and then confirmed several times in Burma and other places, when the Oriental rat has more than one flea per individual host and plague is circulating, plague outbreaks among rats are possible. But what would be the critical index for the northern rat flea has never been as clearly established as it has for the Oriental rat flea."

Nelson gave an example of patterns for which he generally looks. "Mice are a proven plague reservoir. You note, therefore, how many mice fleas are going over into chipmunks. Chipmunks are not considered a plague reservoir but an amplifying host - the chipmunks can amplify plague because they are much more abundant. And then, the chipmunk flea can go onto ground squirrels, which are even more an amplifying host that the chipmunk."

Nelson lamented, as had Smith, the paucity of flea and plague study being done in the United States, noting that most research money went to mosquitos and ticks, because "outside of plague and typhus, fleas are not important as vectors."

Only some 50 flea species have been studied to an extent necessary to provide adequate information about the insect's life cycle. Because fleas are parasitic, they are less often colonized and studied. Nelson explained. "With flea studies, you have to rear the host first. To have a cat flea colony, you have to have cats. For a rat flea colony, rats. Then you've got to set up your lab in such a way that your fleas don't get loose. Mosquitos you can put in a cage and you can get blood and soak it up into pledgets — cotton compresses — and the mosquitos will come and feed there, and you've got your colony going."

What flea biology is known tends to be based on species reared in laboratories — the cat flea, human flea, mouse flea. "If we're going to know more about fleas in their relation to transmitting diseases," said Nelson, "then we have to know more about the biology of wild rodent flea, particularly those we know are good vectors and will bite people."

The future of flea research appears bleak. "There aren't many people who are studying fleas. The great men have passed away. Most of the giants or the good workers have died recently or are in their 50s, 60s, 70s. The Baroness Rothschild's eyesight is going. There are only a few younger people that have come in that are in their solid 40s, early 50s."

Going through the card catalogues in libraries, I said, I'd noted much of the flea literature was in Russian. Nelson acknowledged that the U.S. had done far fewer flea studies than have the Russians. "Because," said Nelson, "Russia has so much plague, particularly in the area in Russia that is equivalent to the Great Basin in the United States, our great plague area. How many deaths from plague there are in Russia, no one knows because they do not report their plague deaths."

In the USSR, said Nelson, "they have realized how savage plague can be and have a more enlightened approach to the seriousness of the disease and its potential than does the U.S. We have one federal plague lab and several state labs. The Russians have at least 11 plague stations."

Two international flea congresses have been convened, the first in Sweden in 1975, the second in England in 1977. Nelson attended both. (No doubt out of modesty, he neglected to mention that an abstract he prepared with another state biologist, entitled "Ecology of sylvatic plague in Lava Caves at Lava Beds National Monument," was read at the English congress.)

"Fascinating, fascinating," said Nelson about the congresses. "In Sweden there were only 16 of us. I was the only person from the U.S. The rest were European. Several of us spent one evening looking at slides that had various parasites on them. A Dutch entomologist, who speaks seven or eight languages, would be rattling off in one language, then another. It was very enjoyable."

One of Nelson' fondest wishes would be to have convened a flea congress in a country to which scientists from the Eastern bloc could come. "The steppes of Russia, particularly as you're going down to the Kurdistan area and Iraq and Iran, to those people who have been there and described the habitat, it is so similar to many of our high desert areas where we have plague. To be able to be able to talk to people who are dealing with almost the same kind of habitat so you could get clues, that would be wonderful."

When he spoke of fleas (and flea congresses), Nelson often turned to perfervid adjectives: "stunning," "dazzling," "fabulous." His manner became not unlike that of a opera fan, describing a favorite diva.

He received his Ph.D. in ectoparasitology in 1968 from the University of California at Berkeley. From the beginning of his academic career, he found himself interested in the "whole gamut of parasitism." But he did his dissertation in bird lice, and only after he entered the state's employ in 1971 did his interest in fleas began to grow.

This turn from bird lice to fleas, Nelson admitted, began as an entirely practical matter. "When you go to a health department, you're looking for diseases that cause problems with people. It boils down to fleas and plague, ticks and Lyme disease and Rocky Mountain Spotted Fever. Not bird lice. When I first came on here, there were already people able to identify ticks." So Nelson was assigned to flea identification. "But the more I got into fleas, the more I got fascinated."

I had asked to look at the ground squirrel flea, Diamanus montanus, in Nelson's compound microscope. Nelson adjusted the scope, gestured me toward it, saying, "Just look at how fancy this is, and it's only a plain ordinary one."

Magnified 430 times, I saw Diamanus's head. At this magnification I could see the actual sharp cutting edge of the "jackhammer" proboscis. Rising from the Diamanus's bluntish head, I saw the antennae. I had seen the antennae, clearly, through Ted Smith's 48-power microscope. Under Nelson's microscope, however, I was able to see bristles at each antennae's end. I could see the leg segments, each of the six legs' two-pronged claws.

At this magnification, the complex structure of the male flea's terminal segment showed itself with great lucidity. Directly above the anus, there was the sensilium, roughly oval in shape and so thickly bristled it appeared tufted. Nelson said, "It is thought that [the sensilium] picks up vibrations or differences in gasses, carbon dioxide, and is used therefore in sensing a host."

The male genitalia in fleas are considered the most complicated genitalia of any group of organisms known in the animal kingdom. Intricately curled and coiled structures filled the last third of the male Diamanus. Nelson pointed out the two penile rods, "wound up," he said, "like a watch spring."

Away, then, from the microscope, returned to a world in which everything was the size to which I was accustomed. I thought for a moment of the afternoon on the patio with Molly, the cocker spaniel. The flea I'd watched traversing Molly's pink stomach had appeared, then, as no more than a rust-colored speck.

From his bookcase, Nelson took down one of six thick green volumes, on whose spines are printed in gold, Catalogue of the Rothschild Collection of Fleas. He turned pages, showing one after another detailed drawings and photographs of fleas. On some species, combs and spines atop the heads resembled feathered war bonnets. "The pictures done here are absolutely stunning. There's real beauty in these things."

He turned to a drawing of a flea whose host is an Australian marsupial. "Dr. Rothschild's father, Nathaniel Charles Rothschild — butterflies, that was his thing. Then, in 1893, he happened to buy some insects from a collector, and one of those insects was a flea from an Australian marsupial — the helmet flea, Stephanocircus dasyuri."

Nelson's voice deepened with emotion. "In the British Museum, I have seen that very specimen. Once Dr. Rothschild's father saw that flea, there was no turning back."

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