Trap them. Bash them. Guillotine them. Smash them. Poison them, or even phone the Pied Piper. The list goes on when it comes to making a better mouse or rat trap, and add to this the city of Malmö, Sweden, where they have a new twist: skewer the varmints.

The new technique, which has passed on the job test in Denmark since 2008, consists of an electronic unit with sensors and batteries that operates the device and a mechanical part with 14 power thrusting spears.

According to the operators, VA Syd, who service the sewers in Malmö and Lund, the result is devastating and rats are killed instantly. The prey is then washed away by the water in the sewage pipe system and the trap automatically reloads itself for the next victim.

"We think it is important to use a method that is both efficient and which is not as painful as the traditional. The rest of Sweden traditionally uses rat poison in which the rat dies of internal bleeding. The new method is also more environmentally friendly because we do not contribute to further spreading the poison into the environment," according to the city's pest control authorities.

The traps also have an SMS feature that sends a message to a technician. The skewer execution system was first installed at about a dozen locations in May, and the sewage pest management team says that their total will soon pass one thousand kills.