By CVA Exterminators, Inc.
If you've been setting rat traps for weeks and you still hear scratching in the attic at night, you've run into the main limit of trapping. A trap only catches a rat that decides to go to it, and most rats won't. Most rodent problems start outside: the rats use your house for shelter and go outside to eat. As long as they can find dog food, bird seed or fruit in the yard, they have no reason to go near a trap. Traps start to work once the rats can't get out to eat. That means closing the gaps they use to get in and out of the house, and taking away the food in your yard.
CVA Exterminators has served the Santa Clarita Valley since 1998. We don't recommend trapping alone. We close up the house first and set traps inside second.
Why are rats ignoring my traps?
Rats ignore traps for two reasons: they're wary of anything new, and they're getting enough food somewhere else.
A trap has to sit on a path the rats actually use. Dan Caballero, CVA's general manager, says placement is key to how well a trap works, and many homeowners don't set their traps in the right spot. Even a well-placed trap is a new object, though, and rats notice new objects. According to UC Integrated Pest Management, rats "quickly detect and tend to avoid new objects and new foods," so they often avoid traps and bait for the first several days, and maybe weeks, after the traps go down. Rats in an attic are often roof rats, the climbing kind, and roof rats are thought to be the more wary of the two common kinds of rats.
Food outside is the other reason rats ignore traps. As Dan says, when rats have food outside, "they will not typically be interested in a trap."
Do rats learn to avoid traps?
Rats do learn to avoid traps. Dan's experience is that once a rat has had a run-in with a trap, it will likely avoid traps from then on. According to UC IPM, "If a rat sets off a trap without getting caught, it will be very difficult to catch the rat with a trap again."
Dan has watched it happen on camera. "I have a game cam video of a rat that we had a really hard time trapping because it was scared of traps," he says. "The rat literally was climbing over a pipe and once it caught sight of the trap it sprung backwards to get away."
If you have traps set right now, each rat that sets one off and gets away becomes harder to catch. That's why Dan says setting traps "is only recommended once the conditions are right for them to work properly." The right conditions are a house with its gaps closed and, where possible, a yard with the food taken away. Sometimes the food source is next door, such as a neighbor's fruit tree or pet food.
Why do I still have rats after catching a few?
Catching a few rats doesn't close the gaps they used to get in. As long as an opening stays open, new rats can follow the same route into your house and replace the ones you caught.
What works better than trapping alone?
What works better is trapping as the last step, inside a house the rats can no longer leave to eat. This is the order we work in:
Find where they're getting in. A CVA inspector goes through the attic, the inside of the house and the outside to find the openings the rats are using.
Close the entry points. UC IPM calls sealing rats out of a building "the most successful and longest-lasting strategy for rat control around structures." Closing the gaps keeps new rats out. Any rats still inside are shut in on purpose. They can no longer go outside to eat, and hunger is what gets them to the traps.
Take away the outside food. Pet food, bird seed, fallen fruit and trash in your yard all feed rats. The next section lists the changes to make.
Get the rats used to the traps. Traps go inside, in the attic, the garage and the other spaces the rats are using. We try to use traps the rats haven't run into before. If the inspector feels it's necessary, we also leave the traps baited with the trigger unset, so the rats get comfortable eating from them. This is called pre-baiting. University of California rodent specialists suggest pre-baiting for 5 days or so before setting the trap.
Set the traps and rebait. Once the rats are comfortable eating from the traps, we set them and rebait. "In desperation and hunger they will hit the trap which allows us to get the problem under control," Dan says.
Watch for trap shyness. In rare cases, we set up game cameras to see how the rats are moving and whether one is avoiding the traps. If one is, we find ways to disguise the traps in the hope that the rat can be fooled.
What can I change in my yard to keep rats away?
Taking away food and hiding places in your yard gives rats less reason to stay around your house. These are the changes to make:
Feed pets only what they'll eat at one feeding, and store pet food in rodent-proof containers.
Keep bird seed off the ground. Better yet, skip bird feeders. Dan calls them a sure way to invite unwanted pests into your yard.
Pick up fallen fruit from citrus, avocado and other fruit trees.
Pick ripe vegetables from the garden promptly.
Replace damaged trash cans and keep the lids closed.
Thin or remove ivy, star jasmine, honeysuckle and other climbing plants on fences and walls. Roof rats nest in thick plants like ivy and use them while they search for food.
Trim tree limbs back so they're at least 6 feet from the roof. Branches touching the house or hanging close to the roof let rats jump onto it and get in from up there.
Clear clutter and other spots where rats can hide and nest. Dan says keeping "clutter and harborage areas" to a minimum is "key to reducing the likelihood that rats move in to the yard."
Dan has noticed that areas next to greenbelts seem to have more rats, though rats do show up anywhere.
Keep these changes up after the house is closed up, wherever you live. UC IPM warns that if sanitation, like the food and clutter cleanup above, isn't maintained, the benefits of other work such as sealing and trapping are lost, and "rats will quickly return."
Sealing and trapping control the rats in your home, but we can't promise that no rat will ever show up again. A yard that still gives rats food and shelter keeps drawing them back.
What does a rodent inspection and sealing visit include?
A rodent inspection from CVA covers the inside of your home, the attic and the outside, and you get a written report showing where rodents are getting in. Rats can squeeze through small gaps, so UC IPM recommends sealing every hole larger than 1/4 inch.
Sealing can include repairing damaged vent screens, sealing gaps at eaves and gables, sealing attic vents, closing small gaps and holes in stucco or siding, and sealing around doors and the places where pipes go through walls. In garages, Dan points to two entry points:
The bottom of the garage doors. Dan names the bottom seal of the main garage door, and a gap under the side door into the garage, as the top places rats get into a garage. The main door's seal is rubber, and rats can chew through it.
Cut vent screens. Dan names these as another place rats get in. Screened vents on garage walls are often cut to run sprinkler lines, cable or plumbing through them, and the gaps left behind are big enough for rodents.
Once the house is sealed, this is what to expect:
Follow-up visits: starting when the traps go in, we come back, typically over about four weeks, to check the traps and remove anything caught. Most problems are resolved within those visits.
The sealing warranty: sealing typically carries a six-month warranty, though the term can depend on construction features and roof type.
Why do I still hear rats after the house is sealed?
You may still hear rats for a while after the house is sealed. Rodents are nervous about new things in their environment, so it can take up to a week or two for them to get used to the traps and go to them.
Why does sealing matter more before winter?
Sealing is especially important ahead of the rainy, cold weather of winter. Cold and rain push rodents toward shelter, and as Dan says, rats want to stay dry too.
Set up a rodent inspection
If you've been setting traps and you still hear rats at night, give us a call at (661) 765-8938 or contact us to set up a rodent inspection. We'll find where they're getting in, put it in a written report, and give you an estimate for the sealing and trapping. If it's mice you're hearing rather than rats, our mouse control page explains how we handle them. Our office is open Monday through Friday, 8 a.m. to 5 p.m.