Entrepreneur uses Nutella to trap rats in Kemi

A rat infestation has been reported in central Kemi, with the population larger than usual, according to environmental health authorities.

Local entrepreneur Samuli Myllyneva, renovating an old wooden house into a restaurant, discovered the rats after receiving a photo from construction workers. He set traps baited with Nutella, catching seven rats the first day and around 30 over three weeks. Most were small, though one was exceptionally large.

Environmental health officials have inspected the area and confirmed the elevated rat population. Notices have been sent to all property owners in central Kemi, as pest control is their responsibility. Last summer, 50 rats were trapped in the city, and another outbreak occurred this winter, though not all properties participated in control efforts.

“Now more property owners are joining the collective eradication effort. The work has been ordered, and we’re waiting for it to be carried out,” said property manager Eeva Heikkinen.

Researcher Santtu Pentikäinen, who has studied rats in Helsinki, also uses peanut butter—sometimes mixed with oat flakes—as bait. “It’s high in energy, protein, and fat, which rats seek out. It also has a strong scent. I’ve found Nutella to be the most effective,” he said.

Mika Luukkonen, a regional sales representative for pest control company Anticimex, noted that effective baits vary but can include fast food, peanut butter, chocolate, cereal, or oat flakes. However, the most effective bait is a dead rat. “It’s quite cannibalistic. We professionals have found that often the best bait is another rat,” he said.

Pentikäinen suggested that cannibalism may increase in large rat populations due to disrupted social behaviors. “The brown rat is highly social. If one is in trouble, others avoid it. But under extreme hunger, other fears fade,” he explained.

Large renovations may have driven the rats into the open, as they typically avoid visibility. Rats usually stay within a few dozen meters of their nest and food source but can travel kilometers if food is scarce, often aided by human activity.

Pentikäinen doubts rats can ever be fully eradicated, noting that the conflict between humans and rats has persisted for centuries. Recent years have seen rat problems in multiple cities, including Rovaniemi in Lapland, where Luukkonen estimates thousands of rats now exist.

To prevent rat infestations, authorities advise proper waste sorting, keeping trash bins closed, and promptly reporting damaged or overflowing bins. Only sealed, designated composters should be used, and kitchen waste should never be flushed down toilets, as it can attract rats.