Washington, D.C., combats rat problem with technology

August 24, 2018 GMT

Washington, D.C., is arming itself with money, drugs and data to combat rats via a slew of rodent control programs scheduled to start this fall.

Gerard Brown, head of the city’s rodent control program, said he saw a jump of 2,000 more 311 calls about rodents last year, but couldn’t tell if it meant there were more rats or more residents knew who to call. This year he’s getting a $1 million budget boost to use technology, a rodent contraceptive and more engagement with residents and businesses to rein in the rats.

“The problem is that it’s everyone’s problem,” Mr. Brown said. “We all have to work together.”

That’s where data scientist Peter Casey comes in. He wanted to help Mr. Brown’s pest controllers, who reported finding rat burrows about 45 percent of the time in response to 311 calls.

“We were trying to really hard to figure out how to take this data that we have coming in from phone calls and make a model that helps us predict where rats are digging in the ground,” said Mr. Casey, a member of the D.C. government’s new in-house data science department, dubbed The Lab.


He said predicting rat burrows also would help communities with poor or immigrant residents who are less likely to call 311 to complain about rodents.

On Thursday, with his coworkers Kevin H. Wilson and David Yokum, Mr. Casey will publish a paper titled “A Cautionary Tail” on their 18-month effort to create a computer program that provides a mapping model for where rats most likely are burrowing.

The program uses data such as a particular building’s age, the type of business it houses, the number of apartments inside and the proximity of city parks, among others, to develop the predictive map. The Lab tested its predictions by riding along with city pest controllers looking for rat burrows.

“The model worked really, really well,” Mr. Casey said, going on to tout its predictive accuracy.

“Where we thought that they would find rat burrows 80 percent of the time, they were finding rat burrows eight out of 10 times. Where we thought they find rat burrows hardly ever, they were finding once out of every 10 times,” he said.

D.C. officials already are using The Lab’s maps in deciding which businesses are eligible for $350,000 in grant money for trash compactors.

“We’re trying to be more strategic on how to deploy the funds,” said Julie Lawson, director of Mayor Muriel Bowser’s Office of the Clean City. “Focusing on where we know there are rat hot spots, and how to effectively support our business when they get the grant.”

The D.C. Small Local Business Administration debuted the program in 2016 to help small businesses lease trash compactors in a bid to reduce rats’ access to food waste.


But Mr. Brown, the rodent control program chief, said businesses couldn’t always afford to pour concrete beds for the compactors to sit on or the higher electric bills from running the machines, so now the grant amounts have gone up to $16,500 from $13,500.

The trash compactor program is part of what Mr. Brown calls “integrated pest management,” focusing on reducing habitat and food for rats as well as trapping them. “It means you are using less chemicals in the environment,” he said.

‘Rats are genius’

But his team is eyeing two chemicals, including a rodent contraceptive called Contra Pest. The drug sterilizes female rats by preventing them from ovulating. The compound breaks down quickly in their livers so it isn’t excreted into the environment.

The other chemical is dry ice, which Mr. Brown says works well for suffocating rats when pest controllers pump it into a burrow and plug the exits.

D.C. residents soon will have the opportunity to learn how to apply it themselves, thanks to a mishap by Miss Bowser, who Mr. Brown said spoke about dry ice on local TV earlier this year without sharing more information.

“People went out and bought dry ice, and they didn’t know to use it correctly,” he said. “Some people were sprinkling it on the ground. They didn’t know to put it in the [rat] hole.”

A city government spokesperson said the guide will be published sometime next week, along with tips about securing trash bins and installing mesh wire around spots where rats can burrow

The District has long struggled with its own big, brown Norway rats. In 1968 Congress funded a “War on Rats,” dispatching nearly 150 rodent catchers to patrol the city after it was estimated half of the District was overrun with rats.

“Rats have been linked to starting fires, chewing on wires, contaminating food and destroying packaging,” ecologist Bruce Colvin, a former D.C. consultant, said, adding that the furry vermin could be causing billions of dollars in damage.

“In too many cities people want to blame the rat or blame the particular agency,” Mr. Colvin said. “It takes the public working with multiple city agencies.”

Today rodent control also takes multiple cities sharing information on what works and what doesn’t. Officials in the District and cities like Somerville, Massachusetts, are watching New York City closely as it wraps up a one-year test of the rat sterilization drug in its subways and is reporting initial successes.

The District also learned from Somerville, which made headlines three years ago for mapping 311 calls about rodents. The Boston suburb’s data department said it mapped the complaints and analyzed common variables, discovering rodent infestations were common near food waste. The city paid for new trash bins for every resident and inspections for every dumpster, and complaints to 311 halved within a year.

But officials like Alderman Matt McLaughlin, who chairs Somerville’s rodent subcommittee, said good data programs can become victims of their own success. Today, he’s concerned that rat populations have rebounded as redevelopment brought in more people, and funding and the political will for a “War on Rats” ebbed.

“Unfortunately, I feel like a lot of the city has been used to explain why there’s not a problem, as opposed to ... using the data to solve the problem,” Mr. McLaughlin said in an interview last spring.

At the time Somerville was curious about The Lab’s work on predictive analysis. One Somerville data scientist said she “wished” she had the District’s resources to try it herself. Now that The Lab is posting its source code for free online with its paper, she might just get her wish for free.

In the end, experts say no matter how good the pest control program, it’s doubtful any city will ever completely rid itself of rats.

“They’re with us long term. But they can be managed to very low levels in cities.” Mr. Colvin said.

Mr. Brown agreed. “Rats are genius. You have to always be thinking.”