Rodents are discreet: they come out mostly at night and avoid open spaces, so customers rarely get a clear look at one. They do leave traces, though, and droppings are the most revealing. When a technician arrives, the first part of the inspection is spent finding them, counting them and looking at them closely.
Here is how we read them, and what you can learn from them before we even arrive.
Question 1: which species?
In the Paris region, three rodents that live alongside people account for most call-outs: the house mouse, the brown rat (or Norway rat) and, less often, the black rat. Their droppings look different.
| Species | Size | Shape | Typical pattern |
|---|---|---|---|
| House mouse | 3 to 6 mm | Thin, pointed ends, like a dark grain of rice | Scattered along routes, in drawers, behind appliances |
| Brown rat | About 1.5 to 2 cm | Thick, capsule-shaped, blunt ends | Grouped in certain spots: cellars, bin stores, crawl spaces |
| Black rat | About 1 to 1.5 cm | Thin, often slightly curved, pointed ends | Up high: lofts, false ceilings, tops of beams |
Location matters as much as shape. Rat droppings on top of a loft beam point to the black rat, a skilled climber. The same droppings at the foot of a cellar wall suggest the brown rat, which lives at ground level and in drains.
The classic false leads
- Cockroaches: tiny black specks of about 1 mm, like ground pepper, or dark smears in corners.
- Bats: droppings close in size to a mouse's, but they crumble into shiny dust made of insect fragments. Bats are protected in France: they are never treated, you contact a specialist association.
- Dormice: droppings larger than a mouse's, in house lofts, with plenty of noise at night.
Question 2: is the activity recent?
A fresh dropping is black, shiny and soft like putty. Over time it turns dull, greyish and hard, and eventually crumbles when pressed with a stick. Under a torch, the contrast is obvious.
The test we recommend: clean an area completely, then come back 48 hours later. If new droppings have appeared, the activity is ongoing. It is also the most reliable way to measure whether a treatment works, far better than a general impression.
Question 3: how many are there?
A single mouse produces several dozen droppings a day, so a handful does not mean a colony. On the other hand, deposits in several rooms, in different sizes, usually mean several individuals from different generations, in other words breeding is under way. A female mouse can breed from about six weeks old: the gap between "a mouse" and "a problem" is measured in weeks.
Question 4: which way do they come in?
This is the most useful question, and the one that separates lasting rodent control from simply putting poison down. Rodents follow walls and always reuse the same routes. Joining the deposits together traces a map of movement that leads back to the entry point.
Other signs fill in the map:
- rub marks, greasy dark smears along skirting boards or around a hole, left by the fur;
- fresh, pale gnaw marks on cables, packaging or door bottoms;
- a sharp, ammonia-like smell of urine in enclosed spaces;
- footprints in dust, which a little talc can reveal.
This is the first step of the Lock-Down Method: detect. Without that map you treat blind, and the rodents come back through the same hole a few weeks later.
How to clean up droppings safely
Rodent droppings and urine can carry pathogens: salmonella, leptospira (mainly through urine and contaminated water) and, in some regions, hantavirus. The main danger comes from dust being stirred up. Hence a simple rule: never sweep or vacuum them dry.
- Air the room for about thirty minutes before you start.
- Wear disposable gloves, plus an FFP2 mask if there are many droppings or the space is enclosed.
- Spray a disinfectant, or diluted bleach (1 part bleach to 10 parts cold water), until the droppings are soaked. Leave it for a few minutes.
- Pick them up with paper towels, put them in a sealed bag, then in the outdoor bin.
- Disinfect the surface a second time, take off the gloves and wash your hands.
What you can do before we arrive
Photograph the deposits with a coin next to them for scale, and note which rooms are affected. Do not move everything: the original positions help us map the routes. Avoid scattering bait at random yourself, as it complicates the diagnosis and is a risk to children and pets.
Depending on the species, our technicians work under our rodent extermination service, with dedicated treatments for the brown rat and the house mouse. To recognise the animal itself, see our guides to the brown rat and the mouse. When you are ready, you can book online.
FAQ
Your questions
How do you tell a mouse dropping from a rat dropping?
Size first: 3 to 6 mm for a mouse, roughly 1 to 2 cm for rats. Shape helps too: a mouse dropping is thin and pointed at both ends, a brown rat dropping is thick with blunt ends. Location completes the picture, since black rats tend to leave their droppings up high.
Do dry grey droppings mean the rodents have gone?
Not necessarily. They only prove that those particular droppings are old. Clean the whole area and check again 48 hours later: shiny black droppings mean activity is ongoing. If no new deposits appear for several weeks, activity has probably stopped in that spot.
Can I vacuum mouse droppings?
No, not dry. Vacuums and brooms throw particles of droppings into the air, where they can be inhaled. First soak the droppings with disinfectant or diluted bleach, leave it to work, then pick them up with paper towels while wearing gloves.
