I keep noticing a funny smell in different places in our family room. It’s strongest in a storage closet where we did have mice nesting. I’m wondering if I’m smelling mouse pee. Can you describe the smell of mouse pee? M. M., Goffstown, NH

Mouse pee definitely does have a smell but I don’t consider it to be a strong urine type of odor. It’s somewhat more pleasant; some people say mouse urine smells like popcorn. Like any odor though, the perception is personal and hard to describe, but once you smell mouse urine, you’ll remember it. Our technicians can tell as soon as they walk through the door if there is a mouse infestation in a residence.

It takes a pretty serious mouse infestation for the urine odor to be really noticeable because mice usually don’t have any one bathroom spot where urine accumulates. Mice dribble urine as they travel along. A single house mouse typically deposits several hundred tiny urine droplets in a 24 hour period. They do tend to follow the same trails though night after night, so their travel routes eventually accumulate a good dose of mouse pee. In fact, when mice urinate frequently in the same spot, “urine pillars” can form. Urine also accumulates more near nest sites and feeding spots.

Since mice also leave fecal droppings in areas that they frequent, you are more likely to find droppings than evidence of urine (see All About Mouse Poop!) You might be smelling the combined mousy smell of urine, feces, and nest material. If there is carpeting on the floor or absorbent material in that closet, it may be holding the odor.

Find Mouse Pee With a Blacklight

If you have access to a handheld blacklight (UV light), you can actually use it to detect rodent urine since it fluoresces under UV. In dark conditions, mouse urine will fluoresce blue-white to yellow-white, depending on how old it is. Rodent hairs will glow, too. Be forewarned, however, that other things also fluoresce under UV light. Other materials that will also fluoresce include certain lubricants and detergents, some bleaches, pitches and tar, certain glues and adhesives, and sugar and rice kernels. You can usually distinguish glowing rodent urine from other substances by its pattern of small trailing droplets.

Give Colonial a call. We can send out one of our technicians with a trained nose, but that’s not the only way we track mice. A thorough inspection will determine whether you still have a mouse problem needing control.

Photo credit: brx0 / Foter / CC BY-SA

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