Few things are more unsettling for homeowners than realizing something may be living inside the structure of the house.

Scratching sounds in the walls. Buzzing in the ceiling. Droppings appearing on a deck or floor.

These problems are surprisingly common, and the cause is often an animal or insect colony that has found a way into the house structure.

Different pests leave different clues. If you know what to look for, you can often narrow down the culprit quickly.

Scratching or Scurrying in the Walls at Night

If you hear scratching, scurrying, or chewing sounds in the walls or ceiling, the most common cause is rodents.

Mice and rats frequently enter houses through very small openings around foundations, siding, or utility penetrations. Once inside, they often travel through wall cavities and ceilings.

These sounds are usually most noticeable at night because rodents are nocturnal.

If you’re dealing with scratching in your walls, see our guide on mice or rats living in your walls.

Buzzing Sounds or Bees Appearing Indoors

If you hear buzzing in the ceiling or suddenly find bees appearing inside your home, the problem may be a hive hidden somewhere in the structure.

Bees sometimes build hives inside wall cavities, rooflines, or even ventilation ducts.

In one case we experienced, hundreds of dead bees began appearing on the bathroom floor every morning before we discovered that a large hive had been built inside a bathroom exhaust fan vent.

Because ventilation ducts connect directly to the outside of the house, they can accidentally provide easy access for insects looking for sheltered nesting spaces.

Droppings Appearing on Decks or Patios

If droppings appear repeatedly on a deck, porch, or patio below the roofline, the source may be animals living in the eaves or roof structure.

Bats are a common example. They can enter very small gaps along rooflines, fascia boards, or soffits.

In one situation we dealt with, droppings kept appearing on a deck until we discovered that bats had found a tiny gap and moved into the eaves of the house.

Once you know where to look, these entry points are often surprisingly small.

Ants Appearing Every Summer

If carpenter ants keep appearing in the same areas of your house each year, the problem may be a hidden nest inside structural wood.

Carpenter ants prefer damp or water-damaged wood because it is easier for them to excavate.

In our case, persistent ant activity eventually led to the discovery of a massive colony living inside a structural beam after we removed an old deck. The underlying cause turned out to be water intrusion from missing chimney flashing.

You can read that story here: carpenter ants in a structural beam.

Signs Something May Be Living in Your House

If you suspect animals or insects are living inside your house, these are some of the most common warning signs.

• Scratching or movement sounds in walls or ceilings
• Buzzing or insect activity indoors
• Droppings appearing below rooflines or inside rooms
• Ant trails that return every year
• Visible entry gaps around rooflines, vents, or siding

In many cases, the pests themselves are not the root problem. Structural openings, water intrusion, or ventilation access points may be allowing them inside.

Why These Problems Often Repeat

Many homeowners try to solve these problems by treating the pests they can see.

But if the underlying entry point or nesting location remains, the problem often returns.

For example:

• Rodents continue entering through the same gap
• Bees rebuild a hive in the same vent
• Carpenter ants return to damp wood
• Bats reuse the same roofline openings

Permanent solutions usually require fixing the underlying structural issue that allowed the pests to move in.

Quick Answer

If you hear scratching, buzzing, or see droppings in your house, animals or insects may be living inside the structure. Common culprits include mice, rats, bats, bees, and carpenter ants. Identifying the specific signs can help determine what type of pest is responsible.

FAQ

What animal makes scratching noises in walls at night?

Mice and rats are the most common cause, although squirrels or other wildlife can also produce scratching sounds.

Why do I suddenly have bees inside my house?

Bees may have built a hive inside a wall cavity, roofline, or ventilation duct that connects to the outside.

What causes droppings to appear on a deck below the roof?

Droppings below rooflines can indicate bats or birds living in the eaves or roof structure.

Why do carpenter ants keep coming back every summer?

Recurring carpenter ants usually indicate a hidden nest inside damp structural wood somewhere in the house.