When a pest control company says "treatment lasts about 3 months," they're referring to the residual activity of a specific product in specific conditions. But the range across all products is enormous — from essential oils that evaporate in minutes to CimeXa dust that kills for a decade. Understanding these timelines helps you plan retreatment schedules and evaluate whether your service contract provides real value.
Bifenthrin perimeter spray: 60–90 days outdoors. UV degradation and rain reduce effectiveness over time. Indoor crack-and-crevice applications last longer (3–6 months) because they're protected from sunlight and weather.
Lambda-cyhalothrin (Demand CS): 90+ days due to microencapsulation technology. The capsules release active ingredient slowly, extending effectiveness.
Fipronil (Termidor): 5–10+ years in soil for termite barrier treatment. This exceptional longevity is why Termidor dominates termite treatment — one application provides years of protection.
Gel bait (cockroach/ant): 3–6 months before drying out. Replace gel placements quarterly or when visibly dried. Effectiveness depends on the bait remaining moist and palatable.
CimeXa desiccant dust: 10+ years in dry, undisturbed locations (wall voids, behind outlet covers). This is the longest-lasting consumer pest control product available. Moisture degrades it — reapply if it gets wet.
Diatomaceous earth: Indefinite when dry. Loses effectiveness immediately when wet (clumps and becomes non-abrasive). Less effective than CimeXa but lasts similarly in dry conditions.
IGR (Precor/methoprene): 7 months for flea prevention on carpets. The exceptional duration makes it the best value product for flea prevention — one application covers an entire season.
Essential oils: Minutes to hours. Evaporate rapidly with zero residual. This is the core limitation that makes them impractical for serious pest control.
Foggers: Effectively zero residual. The active ingredient settles as a thin film that degrades within hours. No meaningful long-term effect.
UV light: Direct sunlight degrades pyrethroids rapidly. Apply perimeter sprays in late afternoon/evening.
Rain: Washes away residue from treated surfaces. Most products are rain-resistant once dry (30–60 minutes) but prolonged heavy rain reduces residual.
High traffic: Walking over treated surfaces, cleaning treated floors, and mopping removes product. Avoid mopping within 2 inches of baseboards to preserve the treatment zone.
Organic matter: Soil, mulch, and debris absorb product before it contacts pest surfaces. Clear mulch from the treatment zone.