Michelle L. Picard ’15 didn’t believe the rumors about mice in the River Houses when she moved into Adams House. That changed. She woke up one morning to find a mouse in her toilet.

“I flushed him,” Picard said.

Picard isn’t the only one at Harvard with rodent experiences. During Thanksgiving break, Doo Young Na ’14 and his brother were hanging out, playing FIFA in a mostly abandoned Cabot House, when he saw out of the corner of his eye what looked like a “big chunk of dust” running through the room.

“Given that there are ‘no rats in the Quad,’ I thought it was just a huge chunk of dust. Then the dust appeared again and changed directions,” Na said.

Na and his brother went back to FIFA, but later, when they saw the mouse again, Na said they “freaked out” and decided there was no option but to try to catch it. After “running around the room like crazy,” the brothers gave up and went to bed. Na successfully caught the mouse the next day with a mouse trap and peanut butter.

Allison J. Scott ’14 often sees what she suspects is a family of rats eating from a trash can in the annex of Kirkland House. Scott suggested emptying the trash can more often, noting that rat poison would be dangerous with the number of dogs on campus, especially in Kirkland.

Gary D. Alpert, associate of the Museum of Comparative Zoology who used to be entomology officer of Environmental Health and Safety for Harvard, agreed with Scott that the solution comes from denying rodents their source of food.

“The correct strategy is exclusion,” Alpert said. “The University has done that successfully.”

Each of the Houses has a pest control program in place, according to Leverett Building Manager Paul Hegarty. But the rat problem isn’t all in the House’s control. Many rodents spend nights scurrying around the MBTA in Harvard Station.

“I took the last train from downtown to go back to the school and got off at the Harvard, and there were these rats on the platform just sniffing around,” Na said. “They were huge.”

George Williams, staff entomologist of regional pest control company Environmental Health & Safety, explained that because Greater Boston is one of the oldest urban areas in America, Cambridge is very susceptible to rats.

“There are tunnels that lead to tunnels that lead to even more tunnels that we don’t even know about,” Williams said

Other factors, according to Williams, include the downturn in the economy, which has led to abandoned properties and budget cuts.

EH&S provides pest control services for the greater Boston area, focusing on structural exclusion of pests. Harvard is not one of the company’s clients, but it does provide inspections, consultations, and services for properties that are managed separately within the Harvard community.

Harvard has taken steps to address the campus rat problem in the past. In 2009, Harvard spent roughly $250,000 to purchase rodent-resistant trash cans for North Allston. Last Monday, the Cambridge City Council unanimously approved an order to devote more money and attention to the presence of rats in the city.

The issue is not foreign to the Council. It is one that Councillor Minka Y. vanBeuzekom has championed in her tenure. She said that she ran for City Council after working with people in her neighborhood to combat the rodent problem in the city.

“The only way to do it is to do it slowly but steadily over a long period,” vanBeuzekom said.

—Staff writer Kerry M. Flynn can be reached at kflynn@college.harvard.edu.

—Staff writer Maya S. Jonas-Silver can be reached at mayajonas-silver@college.harvard.edu.