Pest controllers and Environmental Health in Jersey are reporting a 20% increase in callouts due to rats coming into people's homes since March this year.
They also say they have seen a general increase in rodents over the last five years.
The new figures are most likely due to the mild weather, seen in recent months, with colder temperatures usually acting as a natural population control.
Their advice to residents is to 'pest proof' their homes and clean everything thoroughly if they have had an infestation.
They also added that, for people in rental accommodation, it could be the landlord's responsibility to deal with the issue.