Is the fresh hole along your Marshalltown foundation a Norway rat burrow?

Most people in Marshalltown never see the rat first. They see the hole. It turns up in October beside the back stoop or along the garage wall, a dark opening with a little apron of loose dirt in front of it, and it was not there when the hose got put away. That hole can tell you a lot before anyone goes down it with poison or a shovel.

What dug the hole along my foundation?

Around an Iowa house the short list is chipmunks, voles, thirteen-lined ground squirrels, the occasional woodchuck, and Norway rats. Of those, the rat is the one that matters for the house itself. A rat burrow sits tight to a structure and can lead inside. When it is a rat, it is work for a rat exterminator in Marshalltown, not a yard chore.

The others mostly stay in the yard. A woodchuck hole is far bigger, wide as a dinner plate, with a heap of dirt you could fill a wheelbarrow from, and it usually sits under a shed or at the edge of a fence line. Chipmunks, voles and ground squirrels dig smaller and leave different signs, covered below. Skunks and raccoons tear up a lawn for grubs in fall, which looks like shallow scrapes and flipped sod, not a tunnel.

What does a Norway rat burrow look like next to a house?

Look for an opening about the width of a fist or a little less, with a smooth, packed rim worn by traffic. Loose dirt is fanned out in front of it, and there is often a second hole a few steps away. It is almost always against something: the foundation, a concrete stoop, the edge of a slab or patio, under a deck, under a shed floor, or beneath a woodpile.

Rats like a roof over the entrance. A stoop poured on fill, a garden shed set on blocks, a stack of firewood that has not moved in two winters, or the dead space under the back steps all give them one. The burrow runs under that cover and often follows the edge of the concrete, where the soil was disturbed when it was poured and digs easily.

The rim is the giveaway. A hole that rats use every night gets polished. The dirt at the lip is packed hard and slightly shiny, and the roots at the edge are rubbed bare.

Could it be a chipmunk, a vole or a ground squirrel instead?

Often, yes. A chipmunk hole is neat and round with no dirt pile at all, since the chipmunk carries the soil away, and it tends to sit by a wall, a planter or a woodpile. Voles leave several small holes joined by narrow runways worn into the grass. A thirteen-lined ground squirrel digs its hole out in the open lawn, away from the house, where the grass is short and it can see a long way. A rat wants cover over its head.

Wasps flying in and out of a hole in the ground mean yellow jackets.

Is anything still living in the burrow?

Close it loosely and look the next morning. Kick a little loose dirt into the opening with your boot, or pack in a handful of soil, near dark. If it has been pushed back open by morning, something is living in it and using it nightly. If it stays closed for two or three mornings in a row, the burrow is probably abandoned or the animal has moved to another opening nearby.

Other signs show up if you walk the foundation slowly:

• A worn path in the grass running along the foundation or from the burrow toward a shed, a compost bin or the bird feeder. Rats travel the same line every night and the grass along it goes flat and then bare.
• Fresh gnawing at the bottom corner of a wooden shed door, or on the wood trim where the shed meets its floor. The chew marks are rough and big, with splinters on the ground.
• Dark, greasy rub marks at the edge of a gap they squeeze through, on a concrete block or a pipe where it enters the ground.

Why do rats show up near a Marshalltown house in the fall?

Food outside is going away while the food at the house stays put. The gardens are done, the tomatoes are pulled, and the fields around town have been cut, so the spilled grain and cover rats lived on all summer thin out.

Most of what draws a rat to a town lot is ordinary:

• A bird feeder that drops seed on the ground every day. In fall people fill them more, and the seed under the feeder is a nightly meal.
• Dog or cat food kept in the garage in a bag, or a bowl left out on the porch.
• A compost pile or bin with kitchen scraps in it.
• Trash and recycling cans with lids that do not close, or bags set out the night before pickup.
• Apples or pears dropping in a back yard nobody is picking up anymore.

Older sewer lines play a part too. Rats follow water and cover, and an old cracked line can give them both. This is a different story from the mice that come in after harvest, which move as a wave out of the cut fields. Rats pick a spot near food and dig.

Why not pour poison down the hole or fill it with dirt?

Filling the hole only moves the door. A rat burrow has more than one opening and more than one chamber, so a rat that finds the front blocked digs a new exit a few steps over by morning, often closer to the foundation than the first one was. It is easy to spend a whole fall shoveling the same burrow shut.

Poison down the hole has its own problems. Bait outdoors does not stay with the rat. A dog can dig it back up and birds pick at what spills. An owl or a cat that catches a sick rat eats the poison along with it. And a rat that eats it and goes back down to die can end up under the slab or the stoop, where nobody can reach it.

A pro starts from a different place. The first visit is about reading the whole lot: where the burrows are, which ones are active, where the food is, and where the burrow system comes up against the house. Then the food gets closed off and the burrows get watched from outside, with exclusion work where the tunnel meets the foundation. Our cost page shows what rodent control costs here.

Does a burrow outside mean rats are in the house?

Not always. A burrow out by the compost or under a detached shed can stay a yard problem for a long time. It becomes a house problem when the signs move to the house itself:

1. The burrow sits right against the foundation, or under a stoop, slab or attached garage, where a tunnel can follow the wall down.
2. Night noises are heavier than mice make. A thump or a run in the basement ceiling or a wall, rather than a light scratching.
3. Gnawing turns up on wood at the house, such as a basement window frame or the sill along the foundation.
4. Activity in the garage, around stored birdseed, pet food or the trash, with droppings or tipped bags in the morning.

Any one of those means the rats have a route to the house, or are close to having one. At that point it is rat work at the house, and the burrows in the yard are part of the same job.