You can tell rat droppings from mouse droppings mainly by size. The University of Kentucky's pest control training material says Norway rat droppings are about 3/4 inch long and capsule-shaped with blunt ends, roof rat droppings about 1/2 inch long and pointed on one end, and mouse droppings 1/8 to 1/4 inch long with at least one end pointed. Where you find them narrows it further.
Before you touch any droppings, read the cleanup section below. CDC says not to sweep or vacuum them.
Roof rat droppings
Roof rat droppings are about 1/2 inch long, according to both the University of Kentucky and Cornell's IPM program. UF/IFAS describes them as black and banana-shaped, about 1/4 to 1/2 inch long. They are often slightly curved with a pointed end.
In Jacksonville, you usually find them up high: on attic insulation, along top plates and rafters, on top of kitchen cabinets, in the garage rafters, and under palm trees or fruit trees in the yard. Scattered droppings along a path through the insulation point to a runway.
Norway rat droppings
Norway rat droppings are larger. The University of Kentucky says about 3/4 inch long, capsule-shaped with blunt ends. Cornell's IPM page gives 3/4 to 1 inch.
You find them low: along the garage wall, near burrows by the slab, in crawl spaces, behind appliances on the ground floor and around sheds, woodpiles and seawalls. In Jacksonville they are more common near the river, creeks and port and industrial areas.
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(904) 593-1371Tap to callMouse droppings
Mouse droppings are small, 1/8 to 1/4 inch long, with at least one pointed end. People often compare them to grains of rice or dark sprinkles. Mice leave a lot of them, scattered along walls, in drawers, under sinks and in pantries.
If the droppings you find are small and you're finding them in kitchen drawers, it is very likely mice. The mouse droppings identification article goes deeper on mice.
Fresh vs. old droppings
Fresh droppings are dark, shiny and soft. Older droppings dry out, turn dull and gray, and crumble when pressed with a stick. If you're not sure whether rodents are still active, clean an area carefully and check it again in a few days. New droppings mean current activity.
Other signs help confirm it. The University of Kentucky notes rats leave dark, greasy rub marks along floor-wall junctions and under beams, and that a light dusting of flour or talc can show fresh tracks.
How to clean up droppings safely
CDC's guidance for cleaning up after rodents:
- Open doors and windows for 30 minutes before cleaning, and leave the area while it airs out.
- Wear rubber or plastic gloves.
- Spray droppings and urine with a disinfectant or a bleach solution of 1.5 cups of household bleach in 1 gallon of water, and let it soak for 5 minutes or per the product label.
- Wipe it up with paper towels and throw them in the garbage.
- Don't sweep or vacuum droppings, urine or nesting material.
CDC says diseases mainly spread from rodents to people when they breathe contaminated air, which is why dry sweeping is a bad idea. For large amounts, such as a whole attic, see attic cleanup or droppings cleanup.
Other signs that go with droppings
Droppings rarely show up alone. The University of Kentucky's pest control material describes several other signs that help confirm what you have:
- Rub marks: dark, greasy deposits from body hair along floor-wall junctions, under beams and rafters, and around entry holes
- Gnaw holes: mice make clean-cut holes about 1 inch across, while rat holes are about 2 inches with rough, torn edges
- Tracks: footprints and tail drag marks in dust or mud
Cornell's IPM program adds a detail on gnaw marks themselves: an adult mouse's pair of teeth leaves marks 1 to 2 millimeters wide, while an adult rat's are 3.5 to 4 millimeters wide.
A light dusting of flour or talc on the floor along a wall, checked the next morning, shows fresh tracks if anything is still running there.
What the droppings tell you to do next
Roof rat droppings in the attic mean the work is mostly at the roofline: trapping in the attic and sealing soffits and vents. Norway rat droppings low in the garage mean ground-level sealing and possibly burrow treatment outside. Mouse droppings in the kitchen mean trapping along walls and sealing small gaps.
If you find droppings in more than one area, or you're not sure which rodent left them, an inspection sorts it out.
Talk to a local rodent technicianFree call. Ask for a written plan and quote before any work starts.
(904) 593-1371Tap to callCommon questions
How big are rat droppings?
The University of Kentucky says about 1/2 inch for roof rats and about 3/4 inch for Norway rats. Mouse droppings are 1/8 to 1/4 inch.
Can I vacuum rat droppings?
No. CDC says not to sweep or vacuum rodent droppings, urine or nesting material, since that can put contaminated particles in the air.
How do I know if droppings are fresh?
Fresh droppings are dark, shiny and soft. Old ones are dry, dull and crumbly.
Are rat droppings dangerous?
They can carry germs. Follow CDC cleanup steps: air out the space, wear gloves, wet the droppings with disinfectant and wipe them up.