Every year from late September the calls change. Through the summer, rats live comfortably outdoors in parks, vacant lots and the sidewalk vaults that run under so much of the city. Once night temperatures start dropping into the fifties, that stops being viable and they move toward the nearest reliable warmth, which is almost always a building.
What actually draws them in
Warmth first, then food, then water. In practice that means cellar doors left ajar during deliveries, gaps around utility penetrations, uncapped vent stacks, and the space beneath sidewalk cellar hatches. A rat only needs a gap the size of a quarter.
The five gaps we seal most often
Utility and pipe penetrations in the cellar wall. The gap under a poorly hung cellar door. Uncapped or damaged vent stacks. Deteriorated mortar at the base of the sidewalk vault. Air conditioner sleeves in ground floor apartments.
Why baiting alone is not enough
Bait thins the population that is already inside. It does nothing about the route in, so the following week another animal simply uses the same gap. Anything worth paying for in the autumn combines treatment with physical exclusion.
What to do this month
Walk your building line with a torch after dark, when activity is easiest to spot. Look for grease marks along the base of walls, droppings near the bins, and fresh gnawing on cellar timber. If you find any of the three, get an inspection booked before the first hard freeze rather than after.
