Yes, Ortho Home Defense Insect Killer does kill wasps. Wasps and yellow jackets are explicitly listed on the product label as target insects. The active ingredient, bifenthrin, works on contact or ingestion by disrupting the wasp’s nervous system. That said, Ortho Home Defense is a perimeter spray, not a dedicated wasp-nest killer, and that distinction matters a lot depending on what you’re actually trying to do.
How It Kills Wasps
Bifenthrin, the active ingredient in Ortho Home Defense at a concentration of 0.05%, is a Type I pyrethroid. It attacks the central and peripheral nervous system of insects by interfering with sodium channels, the tiny gates that let electrical signals travel through nerve cells. Normally those channels open and close rapidly to transmit signals. Bifenthrin holds them open longer than they should be, which floods the insect’s nervous system with uncontrolled impulses. This leads to paralysis and death.
The compound works through both direct contact and ingestion. A wasp that walks across a treated surface or gets sprayed directly will absorb the bifenthrin through its body. This dual pathway is what makes perimeter sprays useful as a deterrent: even wasps that arrive after you’ve sprayed can pick up a lethal dose from the dried residue.
Where It Works Well (and Where It Doesn’t)
Ortho Home Defense is designed as a barrier treatment. You spray it along your home’s foundation, around window frames, doorways, and other entry points. It’s effective at killing individual wasps that land on treated surfaces, and it can help prevent wasps from establishing new nests in treated areas. If you’re seeing a few wasps scouting around your porch or garage, a perimeter application can handle that problem.
What it’s not designed for is taking out an active wasp nest. The spray comes out as a liquid stream at close range, not a pressurized jet. You’d need to get uncomfortably close to a nest to hit it, and the formula won’t penetrate deep into a colony the way a dedicated product can. For yellow jackets in particular, which typically nest in enclosed spaces like wall voids or underground burrows, a surface spray can actually make things worse by driving the wasps deeper into the structure rather than killing them.
Ortho Home Defense vs. Ortho Hornet and Wasp Killer
Ortho makes a separate product specifically for wasp nests: the Ortho Home Defense Hornet & Wasp Killer. The differences are significant:
- Spray distance: The dedicated wasp killer shoots a jet stream up to 20 feet, letting you stand well back from the nest. The standard Home Defense perimeter spray has no comparable range.
- Formula: The wasp-specific product uses tetramethrin and sumithrin, fast-acting pyrethroids that deliver rapid knockdown. It also deploys as an entrapping foam that coats wasps on contact and seals nest openings.
- Purpose: The perimeter spray creates a long-lasting barrier on surfaces. The wasp killer delivers an immediate, concentrated dose directly to a nest.
If you’re dealing with an established nest, the dedicated wasp spray is the right tool. If you’re trying to keep wasps from hanging around your home’s exterior in general, the perimeter spray serves that preventive role.
How Long the Residual Protection Lasts
One advantage Ortho Home Defense has over dedicated wasp sprays is staying power. The bifenthrin residue remains active on treated surfaces for an extended period after application, continuing to kill insects that cross the barrier. This makes it useful as a seasonal preventive measure. Applying it around eaves, door frames, and window sills in early spring, before wasp queens start building nests, can discourage them from setting up nearby.
Rain, direct sunlight, and heavy foot traffic will degrade the residue faster on outdoor surfaces. Reapplication every few months during wasp season keeps the barrier effective.
Safety After Application
People and pets can return to treated areas once the spray has fully dried. The formula is clear, fast-drying, and marketed as fume-free, making it practical for use around kitchens, bathrooms, basements, and exterior perimeters. Store the bottle in a cool, dry location away from children and pets.
When spraying outdoors, wear gloves, avoid spraying into the wind, and wash any skin that contacts the product. The CDC notes that high-level exposure to pyrethroids can cause dizziness, headache, and nausea, though normal household use falls well below those thresholds. If you’re spraying near a wasp nest of any kind, even with a perimeter product, do it at dusk or dawn when wasps are least active and least aggressive.
The Bottom Line on Wasps
Ortho Home Defense will kill wasps that contact treated surfaces. It’s a solid choice for creating a chemical barrier around your home that deters wasps and kills stragglers over weeks. For an active nest, especially one in a wall, underground, or high up under an eave, you need a product with longer spray range and faster knockdown. The two products complement each other: use the perimeter spray to keep wasps from coming back after you’ve dealt with the nest.