The city that never sleeps has a problem that never sleeps—rats.

The furry creatures greet New Yorkers on the subway ride to work, in the park during lunch and at home in the evening.  Many feel that there is nowhere to turn for a rest.

Enter Bobby Corrigan. Three years ago, Mr. Corrigan, who holds a PhD in pest control, was hired by the city to restructure its pest control system. Under his guidance, Pest Control Services—a division of the Department of Health—has shifted its plan of attack against rodents and promoted education for residents and business owners on how to combat the vermin.

New York City rat history has several important dates. At the turn of the eighteenth century, sailors brought the Norway rat (Rattus norvegicus) with them from Northern Europe. The Norway rat, separated from other rats by its ability to swim, willingness to eat just about anything and fondness of necrophilia, has since dug a niche for itself in New York and other cities on the Eastern seaboard. Consequently, all rats found in the five boroughs are Norway rats.

In 1949, Dave Davis, an ecologist from Johns Hopkins University, studied the rat population in New York City and determined it to be around 250,000—not nearly the one rat per man that urban storytellers will have you believe. Subsequent research has shown that the rat population has not grown much since.

The city enjoyed its glory days in the world of rat management between World War II and 1981 when President Reagan decreased federal aid to cities. By 1999 the city budget for dealing with rats had been cut down to $5 million.

That all changed in 2000 when Mayor Giuliani was crossed (quite literally) by a rat. After the rodent ran over his foot on the steps of Gracie Mansion, Giuliani boosted the budget to $13 million and called for a “rat summit” to be held at Columbia University. Out of the summit came a “rat czar”—then Deputy Mayor Joseph Lhota and a determination to make the urban environment less rat friendly.

But the rats prevailed. Partially because of increased construction during the boom years after September 11 that forced them out of their underground burrows and partially because of the increased amounts of garbage disposed of during those prosperous times, rats returned to the limelight of NYC public health. After the remodeling of City Hall Park in 2007, the city’s rats found a new home on the park’s very visible lawn. Tourists and natives were not thrilled.

Perhaps the greatest embarrassment came when video of rats taking over a Greenwich Village KFC-Taco Bell restaurant surfaced on YouTube after making the rounds on local TV stations in early 2007. Reporters soon discovered that a Department of Health employee inspected the restaurant in question just one day before. The city forced all of its inspectors to take the training course again.

That same year, Bobby Corrigan took over from Lhota as “rat czar.”

Corrigan was an obvious choice. For four years, he split time between consulting the city on rats and working for his pest management firm in Richmond, Indiana. Before that he taught at his alma mater, Purdue University. Earlier in his career, Corrigan worked for a Long Island company tackling home and business owners’ pest problems.

Corrigan was given control of the Department of Health’s Pest Control Services program. Fighting through bureaucracy—he still has to work with 19 other departments and sacrifice a large part of his time to interfacing with important decision makers—Corrigan has revitalized the program and in turn the fight against rats.

For a long time, especially after the budget cuts of the 80s, the city’s main weapon against rats was baiting. Often this meant using pesticides that when ingested by pets and children proved detrimental and even fatal to health. The prolonged use of pesticides has also increased the rats’ immunities to poisons—although new poisons are being developed faster than rats can become immune to them. Many individuals are also concerned that they cannot retrieve rat carcasses after they have been poisoned (as rats typically return to their burrows to die).

Pest Control Services now take a different approach. They focus on a system carried over from agriculture called Integrated Pest Management (IPM). Developed by entomologists after WWII, IPM focuses on changing the pest’s environment instead of exterminating it. A large part of a pest manager’s day is spent monitoring the unwanted population. If it is deemed to be outside acceptable levels, the pest manager takes action—first through mechanical, then biological and finally chemical means.

Applied to NYC’s rat problem, IPM means a lot of data gathering. In Pest Control Services’ flagship program, inspectors move through the Bronx block by block analyzing both public and private properties for signs of rats. These include tracks on the ground, gnaw marks on the undersides of doors and burrows in back and front yards. Inspectors contact property owners and schedule follow up inspections that, if failed, carry monetary fines for owners. Inspectors are also permitted to apply controls to violating properties.

PCS have also made information available to New Yorkers. Their website contains a booklet that details common myths about rats (e.g. that they can grow to be the size of alley cats; most weigh in at a mere 23 ounces) and tips on how to deal with rodents. There is also an interactive map that displays citywide rat statistics. Corrigan personally runs a three-day class for public and private pest inspectors popularly deemed “Rat Academy.”

Soon, PCS and Corrigan will add another weapon to their arsenal. The program hopes to get a body count on exterminated rats by installing baited boxes (so that the rats cannot run away after they are poisoned) throughout the city. This will give Corrigan another vital piece of information.

But all of this data is useless unless the city and its residents change their everyday habits. Instead of putting out and collecting trash at night (when rats are out and about the most), the city should collect it in the morning, argues Bruce Colvin, an expert on the topic. New Yorkers should also abstain from littering and leaving their trash exposed in plastic garbage bags that rats can easily chew through.

When he wants to make an impression on someone, Corrigan pulls out the dead rat in his book bag and quips “at least we got one.”  Although he knows that we will never get rid of them all, Corrigan still thinks the fight is worthwhile.