Pest control treatment failure happens — sometimes because of factors outside anyone’s control (a severe infestation, re-entry from adjacent units), sometimes because of inadequate treatment, and sometimes because the homeowner’s preparation wasn’t sufficient. Knowing what to do — and how to distinguish a legitimate failure from a treatment that just needs more time — determines whether you get a solution or spend more money on the same problem.

“The first question after a pest control treatment ‘doesn’t work’ is: did it not work because the treatment was inadequate, or because re-infestation is happening? Those are different problems with different solutions. If the treatment was correct and the pest returned, the source of re-infestation needs to be identified. If the treatment itself was inadequate, that’s a warranty issue. You need to know which one you’re dealing with.”

— Renata Voss, licensed exterminator and integrated pest management specialist with 14 years of experience in residential and commercial pest control in the local area

Step 1: Understand What “Not Working” Means for Your Pest

a kid playing baseball

Some post-treatment activity is normal and expected:

Cockroaches: Seeing some cockroaches after the first treatment is normal — the treatment disturbs them and drives them out of harborage. Activity typically increases in the days after gel bait treatment before it decreases. If you’re still seeing significant activity after 2–3 weeks, contact the company.

Bed bugs (chemical): Seeing some bed bugs between chemical treatment visits is expected — eggs survive initial treatment and hatch. The second and third visits address the newly emerged population. Persistent high activity between visits warrants a callback.

Mice: Some activity in the first 1–2 weeks after treatment is normal as bait takes effect. If you’re seeing active movement (live mice, fresh droppings) after 3–4 weeks with no decline, the exclusion work may be incomplete or there are additional entry points.

Ants: Seeing ants for several days after treatment is normal. If activity hasn’t declined significantly within 1–2 weeks, contact the company.

Step 2: Check Your Preparation and Sanitation

A person is holding a spray gun.

Before contacting the company, honestly assess whether you:

  • Followed all preparation instructions before treatment
  • Maintained the sanitation conditions required after treatment (sealed food, reduced clutter, addressed moisture sources for cockroaches)
  • Completed all required preparation steps for bed bugs (washing/drying all linens, vacuuming, etc.)

Some pest control guarantees are voided by failure to follow preparation or post-treatment instructions. If you didn’t follow them, acknowledge this to the company — most will still treat the problem, potentially at additional cost.

Step 3: Contact the Company in Writing Within the Guarantee Period

Contact the pest control company in writing (email) describing:

  • The specific pest activity you’re observing
  • When you first noticed it returning
  • What preparation steps you completed before treatment
  • Your expectation that this falls within the guarantee period

Ask for a callback visit at no charge.

What a good answer looks like: A prompt (within 48 hours) response scheduling a follow-up inspection and re-treatment within the guarantee period.

Step 4: If the Company Disputes the Guarantee

If the company disputes your claim or argues that the guarantee doesn’t apply, ask them to explain specifically what condition voided the guarantee. If their reasoning is not based on a legitimate condition in the written agreement, escalate:

your local consumer protection office (consumerprotectionontario.Ca): For companies that misrepresented their service or guarantee, or that refuse to honor a written guarantee without legitimate cause.

Ministry of the Environment, Conservation and Parks: For complaints about licensed pest control operators who may be operating outside their licence conditions or applying pesticides improperly.

Better Business Bureau: Creates a public complaint record.

Step 5: Get a Second Opinion

If you believe the original treatment was inadequate — wrong product, insufficient coverage, or missed entry points — get a second inspection from a different licensed company. Ask them to assess specifically whether the original treatment appears to have been appropriate for the infestation they’re finding.

A second company’s assessment of the situation provides objective information about whether the original treatment was adequate.

For Bed Bug Treatment Failures Specifically

Bed bug treatment failures are often related to one of:

  • Re-infestation from an adjacent unit (in an apartment or condo): The treatment was effective, but bugs are entering from a neighbor’s unit. This is a building-management issue, not necessarily a treatment failure.
  • Missed harborage sites: Clutter, sealed wall voids, or furniture that wasn’t accessible during treatment.
  • Inadequate preparation: Preparation failures are the most common cause of bed bug treatment failure.
  • Resistance: Bed bugs in some areas have developed resistance to pyrethroid pesticides. Ask whether the company tested for resistance before applying.

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