Sitting in his common room last fall, Dan Geoffrion ’10 was surprised by an unexpected visitor — a mouse.

He and his suitemates chased the creature around the room until they caught it in an empty fish tank. “Whiskers of Steel” became the primary focus of attention in Geoffrion’s suite for a few days. His caretakers fed him regularly on bird seed and trail mix and showed him off to their friends.

Although Geoffrion and his suitemates did not particularly mind the additional occupant of their suite, many other students across campus are bothered by mouse and bug problems in their dorm rooms. Current or past residents of Farnam, Lanman-Wright, McClellan and Welch halls and Davenport and Branford colleges said they have experienced recurring mouse problems, and students in Jonathan Edwards College and Lanman-Wright Hall also reported cockroach sightings. While a representative from Yale’s Office of Facilities said the University’s pest control program is adequate, health experts said the continued presence of mice and other pests can be detrimental to the physical and mental health of students.

Residents of 13 Welch Hall suites reported having seen at least one mouse in their common rooms or bedrooms this year.

Anna Aleksandrova ’10 said that soon after she returned to Yale for the spring semester, she dealt for days with the smell of a dead mouse in her bedroom in Welch C42.

“It started smelling like roadkill,” she said. “It was coming from under my roommate’s bed, and we figured it was under the radiator or stuck in the pipe.”

Aleksandrova said she contacted the Office of Facilities but that when they came two days after her call, they sprayed “some sort of substance” and told her and her roommate that they would just have to wait out the smell, since the dead mouse was unretrievable. Although Aleksandrova said the smell eventually improved, her roommate refused to sleep in the room for three days.

Andrew Rizzo, the executive director of the New Haven Livable City Initiative and a city building official, said many New Haven residents find mice in their homes in the winter because cold weather draws the animals to warm places inside. Rizzo said buildings are rarely condemned because of a mouse infestation, which he classified as “mice all over a floor or throughout a building.”

“I would think with the kind of tuition those kids pay … it behooves Yale to get rid of the mice,” Rizzo said.

Perhaps because of these persistent mice problems, signs reading “Attention. Continuously remove trash, food, and recycles from your suite. Failure to do so will result in a pest control problem” were posted at the beginning of the year in each Welch Hall entryway.

Director of Custodial Services Robert Young said Facilities deals seriously with every report of a pest problem.

“We have a world-class pest control organization, Ecolab, that responds to any complaints of any pests,” he said.

Young said he would not comment further on the matter, and other members of the Office of Facilities declined to comment.

Many students who contacted Facilities about pest problems said pest control personnel had responded but that their attempts to eliminate the pests did not work. Elina Nalibotski ’09 said when she lived in Farnam last year, she found a dead mouse between two bookcases and frequently saw live mice in her common room.

“We called pest control,” she said. “They came and installed traps, but they didn’t help.”

Hande Altun ’09 also said Facilities was unhelpful in dealing with her pest problem. She said the very first night she moved into her suite this year, she and her suitemates discovered they had an extensive cockroach problem. She said they would often see bugs the size of her pinkie running along the walls and floor.

“We called the custodial services, and no one came,” she said. “They didn’t do anything. It was disgusting. It was really hard to live with for a while.”

Psychologists said the feelings of disgust and fear that some people experience when exposed to pests can cause anxiety and unhappiness.

Katie McLaughlin GRD ’08, a graduate student in clinical psychology and public health, said many people have a strong fear of seeing mice and that living with pests can cause people to feel dysphoric or upset.

“There’s actually a lot of research that shows that when people live in places that aren’t well-kept, it sort of brings down people’s morale in general,” she said. “It sort of communicates to them that people don’t care about them. So for a student it might communicate that Yale doesn’t care.”

McLaughlin said anxiety about untidy living spaces could lead to problems with students’ academic performance and ability to concentrate.

Although pests might make people upset, their effects aren’t just psychological — they have also occasionally been shown to cause diseases.

Durland Fish, a professor of epidemiology at the School of Public Health, said although house mice, likely the species found in Yale dorms, are generally clean, they are not totally benign. He said some mice in New York City have been found to transmit Rickettsialpox, a disease which can cause rashes and a fever in humans, through mites living in their fur. Fish said cases of Rikettsialpox so far have only been found in cities larger than New Haven.

Mice and other pests are attracted to spaces where food is available, Fish said.

“If there weren’t any people in the dormitories, there wouldn’t be any cockroaches, and there wouldn’t be any mice, either,” he said.