Cockroaches are nocturnal and avoid light. The ones you glimpse when you switch on the kitchen light are only a small share of the population, and their number says almost nothing about where they live. The monitoring trap fills that gap.
It is a simple glue board or small card shelter coated with glue, sometimes with a food lure. It is not there to wipe out an infestation: it is there to measure and locate it. In the Repère Protocol it is used twice, to locate the sources and then to check how the treatment is working. Here is how to read it.
Where to place them
A cockroach follows edges and walls. A trap in the middle of a room catches little. Place them instead:
- against walls and in corners, with the opening facing the line of travel;
- under the sink, at the back of the cupboard;
- behind or beside appliances: fridge, dishwasher, cooker, coffee machine;
- near pipe entries and service ducts;
- in the bathroom, at the foot of the basin or the bath panel;
- in a bedroom or living room if you have seen an insect there.
Write the date and the location on each trap (for example "under sink, 12/11"). Take a photo of a floor plan of your home with the traps numbered: that is what makes the reading useful.
How long to leave them
One or two nights can be enough when activity is high. For a first reliable reading, allow several nights without moving the traps. Then leave them in place and check them at regular intervals. Replace a trap once its surface is covered with insects or dust: it no longer catches anything.
Reading a catch
What counts is not only how many insects there are, but which ones are caught and where.
| What you see | What it suggests | What to do |
|---|---|---|
| Nothing after several nights | No activity there, or a badly placed trap | Move it against another wall, near a heat source |
| A few adults, no nymphs | Insects passing through, or the start of an infestation | Keep watching, look for where they come from |
| Nymphs (small, wingless) | Breeding on site: a source is close | Focus the inspection around that trap |
| A female carrying an egg case | Active breeding | Treat the nearby area without waiting |
| Far more catches on one trap than the others | A gradient: the source lies on that trap's side | Inspect the hiding places closest to that point |
| An unexpected species | A different origin (networks, common areas) | Have it identified, see our article on species |
| Catches up just after a treatment | Weakened insects coming out | Normal, to be confirmed at the next reading |
| Catches steady or rising at the follow-up | Activity remains | Adjust the treatment at the follow-up visit |
Nymphs, smaller and wingless, are the most valuable clue: they do not travel far. Finding them on a trap means a source is very close. Our article on identifying your cockroach helps interpret a captured adult.
What a trap does not tell you
Monitoring traps have limits, and it pays to know them.
- No catch does not mean no cockroaches. A badly placed, dusty or overly exposed trap stays empty.
- It does not replace an inspection. It points in a direction; the torch-in-hand inspection finds the hiding place.
- It does not treat. Even when full, it catches only a fraction of the population. Adding more traps will not solve an established infestation.
- A moved trap skews the comparison. To track progress, keep the same spot from one reading to the next.
Monitoring traps in the Repère Protocol
- Locate: the technician sets numbered monitoring traps and marks them on the map of sources, alongside the inspection.
- Treat: the treatment (gel bait dots, growth regulator, localised spraying or dry steam as needed) targets the areas where catches and inspection agree.
- Check: at the follow-up visit, the same traps are read and compared. Their trend guides any adjustment.
- Prevent: traps stay in place after the visit. They support active vigilance: a new catch shows up early.
You can set your own sticky monitoring traps before we come; show them to the technician, they will save time.
Taking stock with a technician
If your traps show nymphs or regular catches, cockroach control starts with a full inspection. For a restaurant, shop or apartment building, regular trap readings can be included in a vigilance contract or an annual contract. Prices are on the rates page and booking is online.
FAQ
Are sticky traps enough to get rid of cockroaches?
No. A sticky trap catches only a small share of the population, and the cockroaches in hiding keep breeding. Its job is to locate the sources and track progress. Getting rid of them takes a targeted treatment of the hiding places, followed by a follow-up visit.
What do small wingless cockroaches on a trap mean?
They are very probably nymphs. They move little, so finding them means cockroaches are breeding very close to the trap. It is a sign that a source has settled nearby and that the inspection should focus on the hiding places around it.
How many monitoring traps does a flat need?
There is no fixed number: you place one per suspect area. In a flat, that usually means under the sink, near the fridge, near the cooker or dishwasher and in the bathroom, plus any room where an insect has been seen.
We find the source before we treat.
Locate, treat, check, prevent: the Repère Protocol applied to your home or your business, anywhere in Île-de-France.