On the History, Nature, and Lore of Rattus Baltimoreanus
By Chris Landers
IT’S MIDAFTERNOON, JUST OUTSIDE the Johns Hopkins Bloomberg School of Public Health in East Baltimore, and the street is filled with the crowd from the nearby hospital-shift-changers and the recently released, all surgical scrubs and crutches. Greg Glass leads the way across Washington Street and makes a sharp left into a different world.
“This used to be a good alley,” Glass says, surveying the expanse of concrete in front of him. “You used to be able to stand right here and they’d run across your feet.”
A bearded, compact man who teaches molecular microbiology and immunology at Hopkins, Glass has made a specialty of studying the alleys of Baltimore and the creatures that inhabit them. He has worked with a variety of animals and studied disease in locations around the world, but here in Baltimore, Glass is a rat scientist.
A few years back, he recalls, a garbage truck was disabled in this alley-the rats had undermined the concrete with tunnels, and as the truck passed through, the alley caved in, stranding the truck along with its cargo of trash. “Then the rats just swarmed,” Glass says.
Glass’ association with the rat goes back to 1984, when he was still at the University of Kansas where he received his Ph.D. the previous year. “All my friends were going off to Colorado, the Philippines, the jungles of Brazil, and I was teaching football players math and complaining vociferously to my adviser,” he says. A phone call came to his adviser from a former student who was working on a study in Baltimore: “They were looking for someone who would go in an alley and catch a rat.” Glass headed east.
Now Glass makes a quick right at a T intersection, through a narrow spot and across McElderry Street, and we’re back in rat country. Garbage bags line the sides of the alley, plywood leans up against a garage door with a large hole at the bottom. Glass points to the evidence outside with a mock serious announcement: “And this is rat poo.”
He needn’t bother. A few feet away, the nocturnal creatures are already stirring, darting across the alley from burrow to trash and back. A single rat, by itself, is unimpressive, particularly in the daylight. They can weigh as much as one and three-quarter pounds but invariably grow in the telling to “the size of a cat.” There are a few in the alley now, rustling through the trash bags.
Judy Easterbrook interjects from a few feet away: “This is a relatively clean alley compared to most of them I’ve been in.”
Easterbrook is tall, with long red hair and an easy laugh. She also has a disconcerting habit, when discussing rats, of tilting her head to the side and saying “aw” in the sort of cooing tone one associates with babies or kittens. She makes the sound now, when something in the garage next to her starts squealing.
Back in the lab, she is eager to show off her rats, drawing down from a shelf two taxidermied rodents laid out on a slab like pinned butterflies. As she reaches up for a third, a woman bustling through in a white lab coat rolls her eyes and says, “She’s not getting that thing down again, is she?”
That thing, once it is down, turns out to be a rat that Easterbrook had a hand in preserving. (“I put the skull back in.”) The rat is mounted as a hunter would mount a bear-reared back menacingly on its hind legs, fangs bared, arms outstretched. That, she explains, is how most people see a rat.
Easterbrook, who is a fourth-year graduate student working toward her Ph.D., and one of Glass’ students, sees them differently.
In 2004, she conducted a sort of one-woman rat census of Baltimore, something that hadn’t been done since 1952 and was proposed by Glass as a dare. Easterbrook found herself wandering the alleys of Baltimore, searching for signs of infestation.
She checked alleys in a variety of neighborhoods (she tried to hit all parts of the city equally), looking for signs-rat droppings, burrows. She returned to some of the alleys with wire cage traps manufactured by the Tomahawk Live Trap Co. in Tomahawk, Wis. (“Home of the original wild trap since 1925”), and basically trapped rats until there were no rats to trap. Setting the traps at dusk, she would return in the morning to retrieve them.
“There were people who would sit out and wait for me to come pick them up in the morning,” Easterbrook says. “People were definitely super excited about it and everybody was always very curious.”
One woman had moved from a neighborhood in West Baltimore, where Easterbrook had been trapping, to a neighborhood on the east side, only to run into her again: “She walked up and was like, `You’re the rat lady,’ and I was like”-she hangs her head-“`Yeah.’ You definitely stick out a little bit.”
According to her paper, which appeared in the journal Vector-Borne and Zoonotic Diseases last year, there are 48,420 rats in the city’s residential neighborhoods, within a margin of error of 14,833 rats.
Her findings surprised Glass, although he acknowledges he wasn’t really sure what to expect. A 1949 study, performed by a Hopkins researcher named David E. Davis, estimated the rat population at 43,200, well within Easterbrook’s margin of error.
There are two conclusions to draw from Easterbrook’s paper. One is explicit: “Rat control methods over the past 50 years have not succeeded in reducing the rat population in Baltimore City.” The other is implied by her inclusion of a number from the U.S. Census Bureau. In the same 50-year period, the human population of Baltimore City has dropped by 300,000.
The rats are gaining on us.
A Reluctant Rat-Catcher
IF YOU SEE A RAT IN YOUR NEIGHBORHOOD, it is almost certainly a Norway rat (Rattus norvegicus), also called the brown, sewer, or alley rat. Another species of rat, the black, ship, or roof rat (Rattus rattus), was once present here, but seems to have been completely driven out by the larger, more aggressive Norway. Both seem to have originated in Asia, the black rat spreading out first and the brown nipping at its heels.
Brown rats appeared in the United States during the 1770s on the East Coast and 1850s on the Pacific, spreading with European colonists on the ships that brought them both here. By the early 20th century they had infested every state in the country. At our modern port, rats are apparently not a problem. A phone call to a Port of Baltimore spokesman drew the following response (after he had finished laughing): “Rats? We’re more worried about terrorists.”
Among animals, rats are unique in the way they relate to man. Elmer McCollum, one of the pioneers of nutrition research, found that their dietary needs are the same as ours. Therefore, McCollum was also one of the first to use rats as test subjects. He received criticism from colleagues for working with vermin at the University of Wisconsin, but when he was asked to join the faculty at Hopkins in 1917, he brought his rats along. McCollum’s research led to the discovery of vitamin A, among other vitamins, and started him on a national campaign to reform the American diet.
Because of their natural tendency to follow man for food, to live where we live, rats are an incredibly effective agent of disease transmission. There is, of course, the infamous bubonic plague, which wiped out up to two-thirds of the population of Europe and Asia during the 1300s. (Experts disagree on whether the brown rat was an agent of the Black Death during the Middle Ages, or whether that role was peculiar to the black rat, which would give the brown rat a heroic role by driving them out, fleas, plague, and all.)
In another paper, currently undergoing peer review, Easterbrook catalogs the diseases of the Baltimore rat. She trapped and tested 201 rats and found that more than half had antibodies for leptospirosis, hepatitis E, and the Seoul variant of hantavirus. Seoul virus, which Easterbrook found in abundance, is a comparatively mild form of hantavirus, with a mortality rate, according to the U.S. Centers for Disease Control and Prevention, of 1 percent. Leptospirosis, also prevalent in Easterbrook’s rats, is a disease spread through contact with rat urine, a common enough substance in infested alleys.
In 1996, a group including Glass and led by Joseph Vinetz of Hopkins, diagnosed several cases of leptospirosis in Baltimore. Two patients had cut themselves on broken glass while walking barefoot; a third cut his hand. A fourth man, homeless, got it while swimming in the Jones Falls. The symptoms of leptospirosis are similar to the flu and can easily be missed by doctors. A 1992 study in a sexually transmitted disease clinic in the city found 16 percent of people tested had it. The CDC reports 100-200 cases of the disease annually, although the rate could be higher-health departments are not required to report them.
Glass and Easterbrook follow in distinguished footsteps as they travel the back streets and alleys of Baltimore. Our city has proved a fertile breeding ground for rat scientists. Because of the rat’s pernicious nature and penchant for spreading disease, the study of rats often has gone hand in glove with the study of ways to kill them.
The 1940s were particularly good years for the scientists, if not for the rats, as Curt Richter, under the auspices of the federal Office for Scientific Research and Development, led a team of researchers out of the Carnegie Building of Johns Hopkins (now the Old Carnegie Building on University Parkway). Their goal was to find an effective rat poison, and Richter later wrote that the program was responsible for the killing of “well over a million rats” between 1942 and ’46.
The killing of rats was a wartime priority. Red squill, the rat poison of the day, was made from a plant found on the Mediterranean seaboard, and Axis powers had cut off supply lines. Officials in Washington were also concerned that the Germans or Japanese would begin using, as Richter later wrote, “rat-borne germ warfare.”
Despite funding from the city, there was considerable friction between Richter’s group and then-Baltimore City Health Commissioner Huntingdon Williams. The main point of contention was whether, as Richter believed, poison alone was sufficient to exterminate the rats or, on Williams’ side, the environment needed to be changed by cleaning up trash and removing food sources.
The environmental solution was also championed by David Davis, a giant in rat research from the Hopkins School of Public Health, who credited sanitation for controlling the rat population after Richter’s poisoning program stopped. Davis found that after trapping and removing half the rats in a city block, the pregnancy rate doubled among those who remained. “Actually, the removal merely made room for more rats” he wrote in 1951. “Reduction of the food and harborage increases competition and thereby decreases the rat population.”
Richter’s autobiographical paper “Memoirs of a Reluctant Rat-Catcher,” published in 1968, took the occasion to snipe at Williams some 20 years after the end of the program. The director of a city rat control program, Richter wrote, “must be a man who is willing to step out into the field to check for himself results of active control measures, and who is not content to sit in his office simply dispensing advice about the importance of eliminating sources of food and places of harborage.”
Christine Keiner, a professor at the Rochester Institute of Technology in New York, is working on a paper about Baltimore’s Rodent Ecology Project, a Hopkins-based group that grew out of Richter’s project and made Baltimore a national model for urban pest control. In an article published last year in the journal Endeavour, Keiner wrote about Richter’s contentious relations with the city government and residents. People living in the testing area were required to leave yards and basements open to Richter’s crew and could be fined if they did not. The researcher also refused to tell city authorities what the effects of his poisons were on humans and pets, citing wartime secrecy. Dogs and cats turned up dead, and in 1943 two children survived poisoning after getting their stomachs pumped.
It is the Williams view that ultimately won out, in Baltimore and elsewhere. A 1957 article in the industry journal Pest Control gives as an example in favor of the environmental solution to rat control an outbreak of typhus in Mount Vernon.
During Richter’s research, as the rat bodies stacked up by the hundreds (Richter reports 900 killed on a single night at Lexington Market) an outbreak of Typhus killed one man and infected five other people in a single block of Calvert Street in Mount Vernon (a seventh man caught the disease while attending the autopsy of the man who died). It was later determined that the disease had come from rats who hitched a ride to Baltimore in railway cars and infested the rail yards between Calvert and Guilford nearby. Richter’s “quick kill” solution would not have prevented the outsider rats from infesting the houses.
It should be noted that Easterbrook found the agent that causes typhus in 7 percent of the Baltimore City rats she tested in 2005 and ’06.
Citywide studies conducted in 1947 and ’49 by Davis lent further support to environmental rat control. Unlike Easterbrook’s study, Davis’ work didn’t concentrate on the residential neighborhoods but took in all the city rats. He found that numbers had plummeted from 165,000 in 1947 to about 60,000 in 1949, due to city efforts to rehab houses, collect trash, and enforce sanitary laws. This approach is essentially the one followed today by the city Health Department.
“Eradication? We don’t use that word”
DR. JOSHUA SHARFSTEIN, who became Baltimore City health commissioner last year, says he met with his New York counterpart before starting the job. Sharfstein says he was told, “`I don’t know what you think this job is about, but you’d better read this book.'”
The book was Rats by Robert Sullivan, published in 2004 and subtitled Observations on the History and Habitat of the Cities Most Unwanted Inhabitants. Sullivan, who spent a year in the alleys of New York, observing, studying, and reading, kept with him copies of the works of Hopkins’ David Davis, in the way that, he writes, “It is said that Alexander the Great kept a copy of the Iliad in a precious casket as he went into battle.”
Sharfstein is now something of a fanatic about the book. In a meeting in his office, Olivia Farrow, the city’s assistant commissioner for environmental health, has to sheepishly admit she hasn’t read it yet.
“The main lesson I took from the book,” Sharfstein says, “is that, No. 1, it’s an important issue in peoples’ lives. No. 2, it’s more than just killing rats. Rats exist because they have access to food and places to live. Rats can breed incredibly. If all you’re doing is killing a few rats, you’re not necessarily reducing the rat population. It really takes a coordinated approach to make major progress.”
Sharfstein’s point man on the rat problem is Ron Cuffie. Cuffie, who has worked for the Baltimore City Health Department for 20 years, is currently in charge of controlling the city’s rat population, a job that has rested with the Health Department since 1947, when the problem of rat control was moved from the Bureau of Street Cleaning. Cuffie speaks softly, almost reluctantly, but warms to his subject. He has the air of a man who knows an awful lot about the rats of Baltimore, and is sick of telling people about them.
That could be because Cuffie is faced with the difficult task of convincing people to clean up after themselves so the city can go in and poison the rats. He receives 100 to 200 calls a week from rat-ridden residents, depending on the season. There are more calls, Cuffie says, in warmer weather, but calls have been high year-round during the last few years. “We could use six weeks of a hard freeze,” he says. Including sweeps initiated by Cuffie’s department, his nine pest-control workers went out on 25,544 calls during the 2006 fiscal year. It isn’t always as simple as cleaning up the trash. Rats infest abandoned buildings, cars, and other areas as well.
“People think, If I don’t have trash, I shouldn’t have rats,” Cuffie says. “You have rats also because of certain social, habitual, recreational conditions, or preferences. Even in housing. Ground-hugging decks-decks that are below two feet [off the ground]-make perfect harborage for rats. Grass cover-all that beautiful ivy, especially, or juniper, that covers the grass. It’s beautiful. It makes perfect harborage for rats-you can’t see the holes.
“People’s gardens-people are like, `Oh, we have a nice garden in our yard,’ or something like that. You feed the rats. Tree stumps make beautiful homes for rats, or living trees for that matter. Fruit trees-people love them, like in Greektown with the fig trees or apple trees-all these kinds of things. Fresh fruit, bird feeders, squirrel feeders.
“So even those people, you go through and the alley’s clean, the yard’s nice, and they have rats, you’ll find reasons as to why that quote `clean alley neighborhood’ has rats. It crosses economic and social barriers. It’s just worse in the lower-income areas in general.”
Cuffie would like to dispel a myth about Baltimore rats. There are not, he says, more rats in the streets because of ongoing citywide construction on the sewer system.
“The sewer line that they’re running, about 80 or 90 percent of the time, is parallel to the old line. The noise that they’re making is not going to bother a city rat,” he says. “When we did Hampden, we found virtually nothing.”
If Cuffie is the behind-the-scenes rat man of the city health department, Jason Morgan is the public face. A tall man with a close-cropped beard, Morgan took time at a recent Southwest Baltimore community meeting, after the serving of refreshments and a group recitation of the Lord’s Prayer, to spread the gospel of rats.
He tells the gathering of some 30 or 40 people, most with plates in their laps, about disease, about leptospirosis and hantavirus. He tells them about the dangers of rat urine and how to catch a rat. (Peanut butter is the best bait, and if you use a glue trap, leave it uncovered in the path of the rats for a few days before uncovering the sticky pad, so the suspicious rat will get used to the new object in its way.) He tells them that rats can jump three feet in the air, that they have poor vision and travel largely through smell, and that their hearing is 40 times better than humans’. He tells them that cement and glass, poured into a rat hole, will not prevent them from emerging somewhere else. By this point in his presentation, most of the people have stopped eating.
Morgan tells them about the rat poison the city uses, an anti-coagulant that turns the rat’s insides to mush, and then gives them the bad news.
“Eradication? We don’t use that word,” he says. “We’re not getting rid of all the rats. What we’re doing is controlling the population. Rats were here before us, they’ll be here after us. This problem . . . is not just a city problem. This problem needs the assistance of the community and the community groups. The only good rat-proofing technique is good sanitation.”
It’s a simple message-the same one Williams tried to deliver in the 1940s and Davis a decade later-but it has proven difficult to get across. For one thing, Morgan acknowledges that he is preaching to the choir. The overlap between the people who are responsible for rat infestations and the people who attend community meetings is not large. Lacking the wartime authority of Curt Richter, the Health Department needs to get signed “release of liability” forms from residents before poisoning their yards, including a pledge to clean the yard and buy new garbage cans.
There is also a certain amount of red tape to get through from overlapping city departments. At the community meeting, a woman complains to Morgan about a building in the rear of her house. “Is this a business?” Morgan asks. “We have other programs in the department we’ll refer that to.” Another woman worries about a city-owned abandoned house she is afraid to pass at night for all the rats. “That becomes a Housing [Department] issue,” he responds, “the reason being that Housing handles abandoned homes.” The woman shakes her head.
Under the environmental model of rat control, responsibility lies, ultimately, with residents. The city can only do so much. A trash-can distribution program a few years ago, for instance, ended poorly when some recipients took the new lidded cans inside to store food in, so rats couldn’t get at it, and put out their trash as before in plastic bags.
“Why don’t we have a rat-fishing contest?”
NEEDLESS TO SAY, Baltimoreans don’t always see things the way the city government does, and a seeming lack of action on the city’s part has been a cause of frustration through the years. No reaction to the city’s rat problem, however, has drawn as much attention as the one mounted by Chuck Ochlech from an East Baltimore bar stool.
“It was the Yellow Rose Saloon, at Rose and Fayette Street,” Ochlech recalls in a textbook Bawlmer accent. “The owner of the saloon, Mike DeLuca, he asked me one day-he said things were getting kind of slow, wasn’t getting much business-`What do you think we can do to drum up some business?’
“Well, the Guide, the paper, had just put out an article the week before about rats in the city, and the idea just came to me: Why don’t we have a rat-fishing contest? And he goes, `A rat-fishing contest? What do you mean?’
“I said, `Well, there’s a moratorium right now on rockfish in the bay, and the reason is so they can replenish. If a lot of people get interested in catching the rats, maybe they’ll have to put a moratorium on killing the rats. So we’ll have a contest and run it just like a rockfishing contest or a bass-fishing contest.’ That was 1993.”
The rules of the Baltimore Association of Rat Fisherpersons (or, yes, BARF) were fairly simple. Only light tackle was allowed (spin-cast, cast, spin, or fly rod). No wet or dry flies, hand or trout lines. There was a $3 entry fee, and rat-fishing licenses were printed up. The tournament took place in the area around the Yellow Rose, and rats were presented (dead) in sealed plastic bags for a weigh-in at the end of the tournament.
“It’s not as dangerous as people think,” Ochlech says. “They think, Well, if you’ve got a rat, the rat’s going to come after you. The rat’s going to try to get away from you if they can. What they would do is, get on, reel it in, and somebody would be standing there with a bat, and when it got close enough they’d smack it.”
Hooks baited with raw bacon and peanut butter were the favored lure for the first few tournaments. In 1995, the last year of the tournament, continued opposition from People for the Ethical Treatment of Animals forced a change to peanut butter-smeared glue traps on the end of the fishing line. The change did little to silence PETA’s charges that the rat fisherpersons were mistreating the animals: “They thought that was terrible, too,” Ochlech says.
The tournament eventually captured the interest of the public outside East Baltimore. In addition to a 1994 City Paper cover story, Ochlech and his tournament were featured in The New York Times, The Washington Post, and, Ochlech says, “It kind of found itself as far away as Johannesburg, South Africa, Australia, Alaska-we got called from all these places on it.
“[Kurt] Schmoke was the mayor at the time, and he even personally called me and asked me what did I think I was doing,” Ochlech says. “The city had the Inner Harbor, they were trying to bring in all these people to see what a nice city we had, and all of a sudden I’ve got this rat-fishing contest going on. So I told him, `Well, if you get rid of the rats, I’ll stop my contest.'”
Around this time, Ochlech says, he received a call from the tourism kiosk at the Inner Harbor to tell him that the Yellow Rose Saloon had reached No. 8 on the top 10 destinations requested by tourists.
Chuck Ochlech is hardly the first to make a sport of rats, although he may be the first to have used fishing tackle. Whether because of their availability, or the sort of company they keep, rats have been used often for entertainment. Ratting, a sport related to bearbaiting and dogfighting, has a long history in the United States and Europe.
Full Revelations of a Professional Rat-catcher, an 1898 work by Ike Matthews of Manchester, England, contains a brief description of ratting:
The Rat-pit is of circular construction, say ten feet diameter, and about four feet six inches deep, the sides being perfectly smooth to prevent the rats climbing up and making their escape. A certain number of Rats are placed in the pit according to the arrangements made with the owner of the dog. Then the dog is put in the pit with the rats to kill them, which a good dog does very quickly.
In his book about the political gangs of Baltimore, Hanging Henry Gambrill, Tracy Melton writes that in 1956 the Baltimore Clipper newspaper announced a ratting contest between the Plug Ugly and Rip Rap gangs at a city restaurant. The advertisement offered cash for vermin to supplement the 130 rats already on hand for the match.
Ratting by a more genteel crew took place as recently as the 1970s at the granaries of Locust Point. It is a widely circulated story-Greg Glass says he heard it from residents when he conducted his rat research in that area. A phone call to Liz McKnight on the subject brought this response: “Yeah, that was me.”
A straightforward woman with an air of one who is used to getting her way, McKnight agreed to meet at Pimlico Race Course, where she sometimes takes care of horses. Rats are a particular problem at horse barns, where feces and grain provide food and straw provides refuge. “Welcome to Rat City,” McKnight says, waving at the horse barns.
McKnight is a master of fox hunting in Harford County. She oversees the care of 120 hounds and 10 horses, in addition to the 15 horses she owns herself. Her father was a blacksmith at Pimlico-he shod Seattle Slew-and her great aunt, she says, was the first female horse trainer in Maryland. McKnight’s love of animals extends even to the fox, which she insists is an intelligent creature that enjoys being chased (“They can get away whenever they want,” she says.) It does not, however, encompass the rat.
She thinks it was a neighbor, a breeder of Jack Russell terriers, who knew about the grain piers, although she isn’t sure where the idea first came from. “Who the hell knows how we picked this sport?” she laughs.
McKnight, along with four or five friends and as many Jack Russells, would make the trip into the city, arriving at the grain piers at dusk, and the doors were opened to let them in. “You had to put your socks over your blue jeans,” she says, “so the rats wouldn’t run right up your leg.”
The terriers needed no training, she says; they were just released inside. It was dark-even with flashlights it was impossible to count the rats. She estimates that 200 would be killed in a few hours, and while no exact tally was kept, the dog owners competed for kills.
“It was fun,” she recalls. “We’d do it for about four or five hours. Really fun-the dogs just wanted to please you. The nice thing was the Jack Russells would snap their necks, drop it, and move on to the next one.”
McKnight knows that ratting, like fox hunting, won’t make her any friends at PETA, but she sees both as a tradition-not an aristocratic tradition, but an older one, shared by dogs and humans.
“Just like hunting is in our blood, it’s in theirs,” she says. “Something in human nature makes you do that.”
Man’s Companion Through the Centuries
BACK IN THE ALLEY near the Hopkins School of Public Health, this time well after dark, a woman in her backyard, barefoot, chats on a cordless phone while a small dark animal gnaws at the bottom of her trash bags 10 feet away. A few rats go down to drink at a steady rush of water that flows unaccountably from a drain pipe into the center of the alley, making a small river of reddish liquid that flows down and into the street. An empty lot, overgrown, is alive with rustling noises. A high-pitched squealing noise comes from the garage opposite.
Two rats spill out of the field, fighting briefly. The smaller of the two darts off and the larger moves boldly under the street light. There are at least a dozen rats visible at once, with the skittering and squealing sounds of dozens more.
The rats remain, and so do the scientists. Glass is gearing up for a study of the movement of rats through the city using microsatellite markers-“real CSI type of stuff,” he says. Previous studies of rat movement, including Glass’ own, involved following an individual rat on foot, with an alley map in hand. David Davis, whose papers are helpfully illustrated with drawings of alleys lined with rat trails, found that rats stay pretty much in the same block their whole lives and fare poorly if forced to move. Individual rats, he found, will cross alleys, but seldom streets.
Yet rats have been man’s companion through the centuries. Judy Easterbrook, with her soft “aw” for the wild-caught rat, is hardly alone. Even Richter, the rat killer, professed a certain admiration for his prey.
Bacteriologist Hans Zinsser’s book Rats, Lice and History is almost certainly the definitive popular work on the history of typhus fever (if you read only one this year. . . ). First published in 1934, it has never been out of print. Zinsser’s writing is wonderfully discursive, and he isn’t shy of mixing philosophy in with his history. Somewhere around page 200, just before he introduces his ostensible subject, typhus, Zinsser compares the species: rats and humankind.
Neither rat nor man has achieved social, commercial or economic stability. This has been, either perfectly or to some extent, achieved by ants and by bees, by some birds, and by some fishes of the sea. Man and the rat are merely, so far, the most successful animals of prey. They are utterly destructive of other forms of life. Neither of them is the slightest earthly use to any other species of living things . . .
Gradually these two have spread across the earth, keeping pace with each other and unable to destroy each other, though continually hostile. They have wandered from East to West, driven by their physical needs, and-unlike any other species of living things-have made war upon their own kind. . . .
Man and the rat will always be pitted against each other as implacable enemies.