What kills a spider instantly?

What kills a spider instantly includes physical methods and certain chemicals that cause rapid death on contact, though humane relocation is often preferable for harmless house spiders as they are beneficial. The fastest way to kill spider instantly is physical crushing with shoe, book, or fly swatter that crushes spider immediately, though this can leave mess and some people prefer not to kill. Vacuuming with strong suction removes spider instantly and contains it in vacuum bag, though spider may not die immediately inside vacuum but will be trapped and eventually die, and you should dispose vacuum bag outside. Chemical methods that kill instantly on contact include insecticide sprays labeled for spiders containing pyrethrins or pyrethroids that kill on contact within seconds to minutes when sprayed directly, though they have no long residual effect outdoors and should be used carefully around pets and children. Hairspray can immobilize spider instantly by coating legs and blocking breathing, though not always instantly lethal. Bleach spray kills on contact but can damage surfaces. Boiling water kills instantly when poured directly but can damage surfaces. For instant kill without chemicals, using cup and paper to trap and then releasing outside is humane alternative, as most house spiders are harmless and eat pests like flies and mosquitoes, so killing is not always necessary unless dealing with venomous species like black widow or brown recluse where professional pest control may be needed for heavy infestations.