Why Rats and Mice Come Back After the Exterminator

The gaps were never sealed

This is the most common reason. Trapping and baiting remove the rodents that are inside at the time. If the openings they used stay open, new rodents follow the same paths. Mice can use a gap the width of a pencil. Rats need about half an inch.

Ask your provider what was sealed, with what materials, and where. If the answer is nothing, or foam only, that is likely the problem. See rodent exclusion.

Food and shelter are still there

Rodents return to places that feed and shelter them. Check for:

• Birdseed under feeders and seed stored in bags in the garage
• Pet food left out overnight
• Trash bags outside carts or lids that do not close
• Woodpiles, clutter and dense ground cover along the house
• Fallen fruit and garden produce

Removing these makes your property less attractive than the one next door.

The source is next door

Rats travel along fences, alleys and drainage corridors. If a neighboring property has piled trash, junk or an overgrown lot, rats can keep coming from there. In Wichita, the city's housing and nuisance inspectors handle those conditions. The reporting guide explains how.

In apartments and duplexes, mice move between units through shared walls. Treating one unit without treating the building rarely holds. See apartment rodent control.

Bait-only service

Some services place bait stations and leave. Bait can lower the number of rats, but it does not stop new ones from coming in, and baited rodents can die in walls. A service that never inspects for entry points or seals them is treating symptoms.

Ask for an inspection that includes the outside of the house, a list of entry points and a plan to close them. The license check guide also lists red flags when hiring.

New rodents or leftovers

It helps to know whether you are seeing survivors of the first problem or a new wave. Signs of leftovers:

• Activity in the same spots as before, within a week or two of treatment
• Droppings that keep appearing in a room that was supposedly cleared
• Burrows that were never filled and still look used

Signs of new rodents:

• Activity in new spots, often near a gap that was missed
• A gap of a few weeks or months with nothing, then a sudden return in fall
• New burrows in a different part of the yard

Leftovers usually mean more trapping was needed. New arrivals usually mean an entry point is still open.

What to ask on a return visit

When you call the provider back, ask:

• Which entry points were sealed last time, and can you check them now?
• Did you find any new gaps?
• Are the burrows in the yard still active?
• Is this covered by any guarantee we agreed to, or is it a new charge?
• What would you change about the plan?

Get the answers in writing if a new charge is involved.

Seasonal pressure

In Wichita, mice that seemed gone in summer often come back in October and November. Fields around the metro are harvested, nights get cold and field mice move toward buildings. A gap that was not a problem in July becomes one in October.

That is why a fall check of garage seals, door sweeps and utility entries is a good habit, even after a successful job. The seasonal guide has a full checklist.

Questions Wichita readers ask

Keep reading

• How to Get Rid of Rats in Wichita

  Wichita rats are Norway rats that burrow near the house. Getting rid of them means taking away food and cover, trapping along their runways and sealing the gaps they use.

• Seasonal Rodent Problems in Wichita: A Year-Round Guide

  Fall brings field mice in from the harvest. Winter keeps them in garages and walls. Spring brings burrows and nests. Summer is the time to seal. Here is what to do each season.

• Steel Wool vs. Copper Mesh for Sealing Mouse Holes

  Both work for small gaps when packed tight and sealed in place. Steel wool is cheap and fine indoors. Copper mesh lasts longer outdoors and in damp spots.

• All rat and mouse articles
• Wichita rules and cost guides