Pest guide

Rats and mice: getting them out and keeping them out

Rats and mice don't just chew wires and get into food. They can carry diseases, and the germs are in their droppings, urine, and nests. The CDC lists hantavirus, leptospirosis, salmonellosis, and rat-bite fever among the illnesses rodents can spread to people. You can't tell whether a rodent is infected by looking at it.

The CDC's plan comes down to three steps: seal up, trap up, clean up.

Signs you have rodents #

Three kinds cause most problems in Texas homes:

• Roof rats are climbers. They usually nest in attics and inside double walls. Tree branches touching the roof give them a road in.
• Norway rats stay low. They burrow under foundations, along slabs, and under piles of stuff.
• House mice are the smallest and squeeze into tiny gaps.

Not sure they're still around? Clean up droppings in one spot and check back. New droppings mean rodents are still active.

Step 1: Seal up #

A mouse can squeeze through a hole about 1/4 inch wide, about the width of a pencil. Look for openings:

Fill small holes with steel wool, and caulk around it to hold it in place. Cover bigger holes with hardware cloth, metal sheeting, or cement. Trim branches that touch the roof.

Step 2: Trap up #

• Use snap traps sized for mice or rats.
• Bait with a small dab of chunky peanut butter.
• Set traps on the floor along walls, with the baited end touching the wall, so the trap and wall make a "T."
• Put traps where you've seen droppings or gnaw marks: behind the stove and fridge, in cabinets, in the attic or garage.
• Check traps every day.
• Rats are wary of new things. If you've seen rat signs for a week but caught nothing, bait the traps without setting them for a few days. Once the rats are eating the bait, set the traps.
• Keep going until you've caught nothing for a week and see no new signs.

Keep traps where kids and pets can't reach them.

About poison baits #

The CDC suggests poison bait stations only if trapping doesn't solve the problem.

• The EPA requires rodent poisons sold to consumers to come in ready-to-use bait stations. Loose pellets are not allowed in consumer products.
• The strongest poisons are limited to professional use because they pose greater risks to other animals.
• Pets and wildlife can be poisoned by eating bait, or by eating a rodent that ate bait.

Step 3: Clean up the right way #

If rodents got into your heating or cooling ducts, the CDC recommends hiring a professional.

Fleas come with rodents #

In Texas, fleas from rats, opossums, and stray cats can spread flea-borne typhus. Texas Department of State Health Services (DSHS) advises treating for fleas before you start rodent control. Otherwise, fleas leaving dead rodents may look for a new host, like you. See the fleas and ticks guide.

Make your yard less inviting #

When to call a licensed company #

• Rodents are in your air ducts or heating and cooling system.
• You've trapped for a few weeks and still see new signs.
• You can't find or reach the entry points, especially up on the roof.
• There's a heavy infestation with lots of droppings and nests.

The Texas Department of Agriculture encourages homeowners to use a licensed applicator for rodent control and to check the license before signing anything. Ask whether the company seals entry points, not just sets out bait. Here's how to check a license.

Photo: "Cimex lectularius (bed bug) (5975917188)" by Gilles San Martin, CC BY-SA 2.0, via Wikimedia Commons. Cropped; this version is licensed CC BY-SA 2.0. Photo: "Centruroides vittatus 209027111" by Sam Kieschnick, CC BY 4.0, via Wikimedia Commons. Resized. All photo credits