Most pest control companies spray synthetic pyrethroids, a class of insecticides derived from compounds found naturally in chrysanthemum flowers but engineered to be more potent and longer lasting. The specific product varies depending on the pest, the location being treated, and the company’s approach, but pyrethroids dominate the residential pest control industry. Common active ingredients include bifenthrin, cypermethrin, deltamethrin, lambda-cyhalothrin, and permethrin.
Pyrethroids: The Industry Standard
Pyrethroids work by binding to sodium channels in an insect’s nervous system. Insects rely on rapid electrical signals to move, breathe, and function, and these signals depend on sodium channels opening and closing in precise sequence. Pyrethroids force those channels to stay open far longer than normal, flooding the nerve cells with sodium and essentially short-circuiting the insect’s entire nervous system. The result is paralysis and death, often within minutes of contact.
There are two broad types. Type I pyrethroids (like permethrin and bifenthrin) cause rapid, repeated nerve firing that leads to tremors and a quick knockdown. Type II pyrethroids (like cypermethrin and deltamethrin) cause a more sustained disruption that blocks nerve function entirely. Many technicians use a Type II pyrethroid for perimeter treatments because the longer-acting nerve disruption provides extended residual kill.
What makes pyrethroids especially popular for residential use is their relatively low toxicity to mammals. They break down quickly in the human body compared to older pesticide classes, which is why they’ve largely replaced organophosphates in home pest control.
Other Active Ingredients for Specific Pests
Pyrethroids aren’t always the right tool. For ants, termites, and cockroaches, pest control companies often turn to fipronil. Fipronil disrupts the central nervous system through a different pathway than pyrethroids, and its key advantage is that it’s non-repellent. Insects can’t detect it, so they walk through treated areas, pick it up on their bodies, and carry it back to the colony. This transfer effect makes fipronil especially effective against social insects like ants and termites, where killing foragers at the surface won’t solve the problem. You’ll find fipronil in gel baits, liquid termite barriers, and granular lawn treatments.
Neonicotinoids are another class professionals use, particularly for pests that resist pyrethroids. Active ingredients like imidacloprid, clothianidin, and dinotefuran mimic a chemical messenger in the insect nervous system, overstimulating nerve cells until they fail. These are common in systemic treatments (where the chemical is absorbed into a plant or applied to soil) and in gel bait formulations for cockroaches and ants.
Professional Products vs. Store-Bought Sprays
The active ingredients in professional sprays are often the same ones found on store shelves. The difference is concentration. Professional-grade products can contain up to 10 times the concentration of active ingredient compared to retail versions. The EPA regulates consumer products with wider safety margins for untrained users, which means lower potency per application. A can of permethrin spray from a hardware store might contain 0.5% active ingredient, while the concentrated product a technician mixes could start at 7% or higher before dilution.
Beyond concentration, professionals also have access to restricted-use products that aren’t available to consumers at all. The EPA classifies certain pesticides as “Restricted Use” when they have the potential to cause harm to the environment, the applicator, or bystanders without added precautions. Only certified applicators, or people working under their direct supervision, can legally purchase and apply these products.
How Technicians Apply the Spray
The standard tool for most indoor and perimeter treatments is a compressed-air sprayer, either a hand-pump canister or a battery-powered backpack unit. These deliver a controlled stream of liquid along baseboards, door frames, window sills, and the exterior foundation. The larger droplet size lets the technician place product precisely where pests travel without it drifting into the air.
For outdoor mosquito treatments or large-scale applications in yards and landscaping, companies often switch to ultra-low volume (ULV) foggers. These machines atomize the insecticide into an extremely fine mist that penetrates deep into foliage, mulch beds, and shaded resting zones where flying insects hide. The tradeoff is less precision: foggers cover a broad area but don’t leave as heavy a residual layer on surfaces as direct spraying does.
How Long the Spray Lasts
One of the main reasons professionals use pyrethroids for perimeter treatments is residual effectiveness. Once applied and dried, these products continue killing insects that cross the treated surface for weeks or months. The exact duration depends heavily on the surface material and whether it’s exposed to weather. Research on residual sprays applied to cement walls found the treatment maintained effective kill rates for roughly six months, while porous surfaces like mud or clay plaster extended that to seven or eight months. Smooth, nonporous indoor surfaces like tile or sealed baseboards generally fall somewhere in that range under ideal conditions.
Outdoor treatments degrade faster. Rain, UV exposure, and temperature swings break down the active ingredients, which is why most pest control contracts include quarterly re-treatment. Interior applications in protected areas (inside wall voids, under appliances, along unexposed baseboards) can remain active the longest because they’re shielded from the elements.
Safety After Treatment
The standard guideline is to keep pets and children away from treated surfaces until the spray has dried completely, or for whatever duration the product label specifies, whichever is longer. For most liquid sprays applied indoors, full drying takes 30 minutes to two hours depending on ventilation and humidity. Granular products used outdoors require more caution: they need to be watered in and fully dissolved before the area is safe, which can mean staying off treated zones for 24 hours or more.
Every professional pesticide carries an EPA signal word on its label indicating its toxicity category. “Caution” marks the lowest acute toxicity (Categories III and IV), “Warning” indicates moderate toxicity (Category II), and “Danger” signals the highest risk (Category I). Most residential sprays fall into the “Caution” category. Your technician should leave behind a service ticket listing the exact products applied, their EPA registration numbers, and any re-entry instructions. If they don’t offer one, ask for it.
What to Ask Your Pest Control Company
Knowing the general classes of chemicals is useful, but the specific product matters. Before or after treatment, ask your technician for the product name and active ingredient. With that information, you can look up its safety data sheet online, check its EPA toxicity category, and verify re-entry times for your household. You can also call the National Pesticide Information Center if you have questions about a specific product’s risks to children, pets, or garden plants.
If you prefer reduced-chemical options, ask whether the company offers an integrated pest management (IPM) approach. IPM-focused companies use targeted baits, exclusion methods (sealing entry points), and habitat modification before reaching for broad-spectrum sprays. The spray itself may still be a pyrethroid, but it’s applied in smaller, more strategic amounts rather than as a blanket perimeter treatment.