Raid can kill spiders, but only when you spray them directly. Unlike the insects Raid was designed for, spiders are arachnids, and they don’t respond well to the residual chemicals left behind on surfaces. A spray that keeps killing ants or roaches for weeks after application will do almost nothing to a spider that walks across the same treated surface later.
Why Raid Works Differently on Spiders
Raid products use synthetic chemicals called pyrethroids, which attack the nervous system of bugs on contact. Different Raid products contain different combinations of these compounds, but they all share the same basic limitation when it comes to spiders: they were formulated to kill insects, not arachnids. The Burke Museum’s arachnology department puts it plainly: these chemicals will kill spiders contacted directly by the spray, and that’s about all.
The distinction matters because most people spray Raid along baseboards, windowsills, and doorframes expecting it to create a lasting barrier. That strategy works reasonably well for ants and roaches, which absorb residual chemicals through their bodies as they crawl across treated surfaces. Spiders, however, walk on the tips of their tarsal claws, minimizing contact with whatever they’re walking on. Their body chemistry also processes these compounds differently than insects do, so even the small amount they pick up from a treated surface rarely delivers a lethal dose.
Direct Spray vs. Residual Barrier
If you see a spider and hit it with a full burst of Raid Ant & Roach Killer or a similar aerosol, the concentrated dose of pyrethroids will overwhelm its nervous system and kill it. This is the one scenario where Raid reliably works on spiders. The spray needs to coat the spider’s body directly.
The residual barrier approach, where you spray and walk away hoping spiders die later, is far less effective. You might occasionally kill a small spider that lingers on a heavily treated spot, but most spiders passing through will survive. Spider egg sacs are even harder to deal with. They are relatively impervious to pesticides, so spraying a sac you find in a corner is unlikely to prevent hundreds of baby spiders from eventually hatching.
Bug Bombs Are Even Less Effective
Raid foggers (bug bombs) are one of the least effective options for spider control. Foggers release a mist of insecticide into the center of a room, but very little of that mist penetrates into the cracks, voids, and secluded corners where spiders actually live. According to entomologists at the University of Kentucky, the pyrethrins in most foggers are “seldom lethal to roaches, ants, bed bugs, spiders, silverfish, and other crawling pests.”
Worse, the ingredients in foggers tend to be repellent, which can scatter spiders deeper into walls and other hard-to-reach hiding spots rather than killing them. You end up with pesticide residue on your countertops and furniture but the spiders simply relocate.
Safety Risks for Cats and Fish
If you do use Raid indoors, the pyrethroid ingredients pose a serious risk to cats. Cats lack the liver enzymes needed to break down pyrethroids efficiently, and even small exposures can cause life-threatening reactions. Signs of pyrethroid poisoning in cats include drooling, tremors, difficulty walking, seizures, and trouble breathing. Keep cats out of any treated area until the spray has completely dried, and if a dog in the household has been treated with a flea product containing pyrethroids, keep the cat separated from that dog for 12 to 24 hours.
Fish are even more vulnerable. The smallest exposure to pyrethroids can kill aquarium fish. If you’re spraying Raid in a room with a fish tank, cover the tank with plastic wrap or move it to an untreated room first.
What Actually Reduces Spiders Indoors
Since chemical sprays offer limited spider control, the most effective approach combines physical removal with habitat modification. A vacuum cleaner or broom removes spiders, webs, and egg sacs on contact, and destroying egg sacs is especially important since each one can contain hundreds of young spiders. This simple step does more than any residual spray.
Spiders prefer quiet, undisturbed spaces: closets, garages, basements, attics, and cluttered storage areas. Reducing clutter in these zones makes them far less appealing. Outside the home, move firewood and stacked debris away from the foundation, and trim back shrubs, vines, or tree limbs that touch the house, since these give spiders a direct bridge to your walls.
Sealing entry points makes a significant difference. Tight-fitting window screens and door sweeps block spiders and the insects they feed on from getting inside. Switching outdoor lights to yellow or sodium vapor bulbs also helps, because these attract fewer night-flying insects. Fewer insects near your doors means fewer spiders following them in.
If you want to monitor for hidden spider activity, sticky glue traps placed flush along baseboards and in room corners are surprisingly effective. They won’t eliminate an infestation on their own, but they reveal where spiders are most active so you can focus your cleaning and sealing efforts in the right spots.