There are several ways to kill cockroaches instantly, according to the search results. Here are some of the most effective methods:

• Baking Soda: Mixing sugar with baking soda will lure the roaches to eat, and the baking soda will cause their stomachs to swell and eventually explode.

• Bleach: Spraying cockroaches with bleach or an ammonia mixture will poison them, but be cautious with this powerful chemical.

• Borax: Borax is a powdery substance that dehydrates the cockroaches’ exoskeletons and kills them.

• Boric Acid: Another powder solution is boric acid, which dehydrates the exoskeleton until they die.

• Pyrethroid-Based Sprays: These sprays are neurotoxic, preventing the neurons from functioning. The roaches become paralyzed and eventually starve to death.

• Roach Fogger: Roach fogger or roach spray is usually an aerosol spray filled with active ingredients that kill roaches immediately.

• Soapy Water: Dousing a cockroach in soapy water will suffocate and kill it. Filling a spray bottle with dish soap and water, shaking it, and spraying a roach from above will kill it quickly.

• Traps: Most cockroach traps will kill cockroaches quickly. Glue traps or bait stations are effective.

• Freezing: Place the insect in a plastic bag and put it in the freezer for a few hours. The cold temperature will kill the cockroach instantly, and it can then be disposed of safely.

• Electronic Traps: These traps use bait to lure the cockroach into a trap, where an electric shock is delivered, killing the insect instantly.

• Hairspray: Though not a home remedy, spraying roaches with hairspray will cause their wings and legs to stick together, suffocating them.

Its important to note that some of these methods may not be practical for treating infestations, and its best to consult with a pest control professional for a more permanent solution.