Why has my cockroach gel bait stopped working?

It worked, and now it doesn’t. That is frustrating, especially when it was the one thing that did. But bait rarely stops working for no reason, and the reason is usually one you can find and fix this week. Go through the causes below in order, simplest first, before you buy anything new.

Check these first

1. Spray or cleaner near the bait. Residue from a surface spray, a fogger or a strong kitchen cleaner puts cockroaches off bait. Has anyone sprayed, or wiped over the dots, since it stopped working?
2. Old, dried bait. Gel that has gone hard and crusty is far less tempting. Dried dots that nobody has touched in a busy spot are a clear sign.
3. Eaten and not replaced. If the dots are gone, they were working. They just ran out.
4. The wrong places now. As numbers fall, the survivors may gather in new spots. Look at where your traps catch them today, not where they were a month ago.
5. New food competing. A pet bowl left out, a new bin, crumbs behind a moved appliance. Bait has to be the best meal around.
6. New arrivals. In a flat, fresh cockroaches can keep coming from next door, which looks like bait failing. See cockroaches coming from next door.

When they have learned to avoid it

If you have ruled all of that out, the cockroaches themselves may have changed. Bait aversion is a known problem with German cockroaches: some groups learn to avoid a particular bait and stop eating it. Some also tolerate certain insecticides better than others. Pest controllers plan around both by switching between baits with different active ingredients.

The active ingredient is in the small print on the label, not in the product name. Two products with different names can contain the same one, so check before you switch.

The fix

1. Stop all spraying anywhere near bait.
2. Clear old dots and wipe the spots with soapy water, then let them dry.
3. Fresh, small dots in the places your traps say they are now: hinges, cupboard corners, around pipes, behind appliances and kitchen units.
4. Switch to a bait with a different active ingredient if you suspect they are avoiding the old one.
5. Add an insect growth regulator if you are not using one, so any young that survive cannot breed. See what a growth regulator does.
6. Count weekly with monitor traps, same spots, same day.

For every product: follow the label, and check it is allowed where you live.

Kids and pets: when you move or refresh bait, keep it in cracks, behind appliances and high inside cupboards. Stations go where children and pets cannot get at them. If a child or pet eats bait, call your doctor, vet or local poison centre with the label to hand.

Bait after a professional spray

If a pro sprayed and it has worn off with a few cockroaches still around, bait is a sensible next step. Ask the company which active ingredient they used. Many pros rotate between different ones so that any cockroaches that survived the first are hit by something else, and a bait with a different ingredient is often the safer choice for that reason. A good pest controller will tell you which fits. Either way, the label decides how and where to use it.

When to call a professional

If you have fresh bait, no spray nearby, a growth regulator in place and the traps still catch young ones after four weeks, it is time for a pro. Show them your dated counts and every product you have used, by active ingredient. Our answer on when pest control is not working covers what to ask.