Do Mice Come Out During the Day: 5 Hours That Tell You

Do mice come out during the day? That is the question I had been asking myself for six weeks before I got an answer I did not want, in my Astoria rental in late August at 1 p.m. on a Saturday, when I walked into the kitchen and saw a mouse sitting on a piece of dropped rice from the night before, eating it with the unhurried confidence of an animal that did not know it was visible. I had heard mice in this apartment before, but only at night, in the walls, in the radiator, in the boxes I had stored under the kitchen counter. I had assumed, because every piece of advice I had read about mice in apartments said the same thing, that mice were nocturnal and that seeing one in the middle of the day meant either that I had a huge infestation or that the mouse in question was sick or dying. Neither of those turned out to be true. The question I had been asking myself for six weeks—do mice come out during the day, or is what I am hearing at night the same animal I would see in daylight if I were awake—got a more complicated answer than the internet was giving me. The simple answer is wrong, and the wrong answer is what makes people either ignore a real infestation or panic about a small one.

The simple answer that everyone gives is that mice are nocturnal, and so if you see one during the day, it is a sign of a serious problem. The slightly more correct answer is that mice are not strictly nocturnal. They are crepuscular, which is the technical word for "most active at dawn and dusk," and they are also flexible, which means they can and do adjust their activity patterns to where the food is and where the danger is not. In an apartment where the food source is in the kitchen and the kitchen is busy during the day, the mice will be in the walls at night and behind the stove during the day, and the renter will think they have a small problem because they only ever see one mouse at a time. In an apartment where the food source is in a basement pantry that nobody opens during the day, the mice will be in the basement during the day and the kitchen at night, and the renter will think they have a nocturnal problem because they only ever hear scratching at 11 p.m. The activity pattern tells you almost nothing about the size of the infestation. It tells you where the food is, and that is information, but it is not the information the simple answer is selling.

The reason the simple answer is wrong, and the reason I want to write this article for any renter who is trying to decide whether to email their landlord about a mouse in the middle of the afternoon, is that the day-versus-night question has two answers depending on whether you are asking about mice in general or mice in your apartment. In general, mice are crepuscular. In your apartment, mice are wherever the food is and wherever the danger is not, and those two things change day by day. A mouse in your apartment that is out during the day is not a sign that the infestation is worse than you thought. It is a sign that the food source is accessible during the day, which in most rentals means the food source is something the renter left out during the day — a piece of dropped rice, an unsealed bag of pasta, a dish rack with overnight water in it, a pantry door that does not latch. The fix is not to escalate the call to pest control. The fix is to find the day-accessible food source and close it, and then watch the activity pattern for a week, and then decide whether the problem is still a problem.

The 24-hour mouse day, and what each hour tells you

Mice in a typical apartment move through a roughly 24-hour cycle. The parts of the cycle you can observe tell you different things about the population.

The hour after sunset (6 p.m. to 8 p.m., depending on the season) is when mice that have been hiding in the walls or behind the stove start moving. If you hear scratching within an hour of sunset, you are almost certainly hearing mice that live in your walls or under your floor. The sound is fast and light and rhythmic.

Two to three hours after sunset (9 p.m. to 11 p.m.) is when the mice that have been waiting near the food source approach it. If you see a mouse at this hour, it has been in your apartment for at least a few days, because bold mice have already mapped the kitchen. This is also the hour when a single snap trap set along a wall with droppings will catch a mouse within a week—the mice are still neophobic enough to investigate a new object within five to seven days.

The middle of the night (1 a.m. to 4 a.m.) is when mice that have been living in the apartment for weeks, the ones that have stopped being neophobic and stopped fearing the snap traps, are out in the open. If you set up a game camera pointed at the kitchen and see four mice between 1 a.m. and 4 a.m., you are looking at a population of at least four. The activity at this hour tells you the size of the population more accurately than a daytime sighting ever could.

The hour after sunrise (6 a.m. to 8 a.m.) is when mice retreat to their hiding places, and when you are most likely to find fresh droppings. Fresh droppings are soft and dark and smear if you touch them. Droppings from the day before are dry and hard and crumble. The difference tells you whether the mice were out last night.

The middle of the day (10 a.m. to 2 p.m.) is when the answer to whether mice come out during the day becomes visible. The answer in most apartments is yes, occasionally, and the reason has nothing to do with the size of the infestation. It has everything to do with the location of the food source. If you have an unsealed bag of rice in a low cabinet, or a piece of fruit that rolled behind the stove two days ago, or a slow leak under the sink leaving a puddle, you will see mice during the day. The daytime sighting is not a cause for panic. It is a clue about the location of the food source.

What my cousin Maya did when she saw a mouse at 1 p.m.

My cousin Maya, who lives three blocks away in Astoria and has been through this twice, told me about her own 1 p.m. mouse when I called her in a panic in late August. Maya's mouse was on her kitchen counter at 11 a.m. on a Wednesday, sitting next to the dish rack, eating a crumb she had missed the night before. Maya had been hearing mice at night for two weeks. The daytime sighting was the first time she had actually seen one. Maya's first call was to a pest control company, which quoted her $450 for an initial visit and a $95 follow-up. Maya's second call was to me. Her third call was to her landlord. The maintenance man found a slow leak under the kitchen sink that was leaving a half-inch of standing water in the cabinet below the sink. That water source was what had brought the mouse out during the day, and it was also what was attracting every mouse in the building to Maya's unit specifically.

The leak was fixed in 20 minutes. The water source was gone within 24 hours. The food source was already sealed, because Maya had read about mice in apartments before and had been keeping her kitchen clean for the two weeks she had been hearing the scratching. The mouse activity dropped to almost nothing within a week, and within two weeks Maya was not hearing any scratching at all. The total cost to Maya was zero, because the leak was a structural repair the landlord was responsible for. The cost to Maya if she had called the pest control company first would have been $450 for the initial visit and $95 for the follow-up, plus whatever the company would have recommended for ongoing service, and the leak would still have been there, and the mice would still have been coming back, because the leak was the food and water source and no amount of trapping was going to fix the leak.

This is the part of the story I want to be clear about, because the lesson is not "do not call pest control." The lesson is "find the food and water source first, and then decide whether pest control is necessary." The order matters. If you call pest control first, you spend money on a treatment that does not address the cause, and the problem comes back in a few weeks. If you find the food and water source first, you may not need pest control at all, and the problem may resolve in a week. Maya's case was a leak. A different case might be a gap under the dishwasher that is letting warm air out, or a piece of food that fell behind the stove three weeks ago and has been feeding the mice ever since. The point is the same: find the source, fix the source, and then see what is left.

What the day-versus-night question actually means

The question do mice come out during the day is, in the end, a question about where the food is, not a question about whether you have a problem. The answer in your apartment depends on the food source in your apartment, and the food source in your apartment depends on what you have left out, where you have left it, and how accessible it is during the hours you are not in the kitchen. If the food source is accessible during the day, the mice will be out during the day. If the food source is only accessible at night, the mice will be out at night. The simple answer — that daytime sightings mean a serious infestation — is wrong in a way that costs renters money, because the simple answer pushes people toward pest control calls that do not address the underlying food source, and the underlying food source is the thing that has to change for the problem to actually go away.

The right answer is the one Maya gave me on the phone in August, which is to spend a week watching before you spend any money. Walk into the kitchen at 6 a.m., at noon, at 6 p.m., and at midnight, and write down what you see and what you hear. After a week you will have a much better picture of where the food source is, when the mice are active, and how many mice you are actually dealing with. If after a week you see evidence of mice at multiple times of day, and you have already sealed the obvious food sources, then it is time to email your landlord with the pattern you observed and the request for a structural inspection, because a multi-time-of-day pattern in a clean kitchen is a sign of a larger issue that the renter is not equipped to solve. If after a week you see mice only at one time of day, and you have found the food source for that time, you may be able to solve the problem yourself with a sealed container, a snap trap, and a week of patience. The day-versus-night question is a clue, not a diagnosis, and the diagnosis takes a week of watching, and the watching is what most renters skip, and the skipping is what most of the bad advice on the internet is built around.

The short version, before you panic about the day sighting

If you see a mouse in your rental during the day, the answer to whether mice come out during the day in your specific apartment is yes, and the reason is almost always that the food or water source is accessible during the day, not that the infestation is worse than you thought. Spend a week watching. Walk into the kitchen at four different times of day, write down what you see and what you hear. Look for the food or water source that is accessible during the day. Common ones are slow leaks under the sink, dropped food behind the stove, unsealed bags in low cabinets, dish racks with overnight water, and gaps under the dishwasher that let warm air out. Find the source. Fix the source. Then see what is left. If after a week the daytime activity has dropped to almost nothing, the source was the problem, and the problem is solved. If after a week the activity is unchanged, email your landlord with the four-time-of-day pattern you observed, and ask for a structural inspection of the kitchen, the basement, and any adjacent units. A paper trail with specific times of day and a specific food source observation moves the request faster than a panicked phone call about a single sighting ever will.