Boric acid is extremely lethal to cockroaches and is found in 20 Mule Team Borax, a common household chemical often used to enhance the performance of laundry detergent. If you're dealing with a roach problem, borax can help you exterminate these unwanted house guests. You can use the borax in powder form to dust areas where roaches hide or you can use it to make bait stations that will attract and kill the roaches.
Mix the borax with equal parts sugar or flour. Place a few pebbles or pennies in the bottom of your squeeze container to prevent clumping and then add the insecticide mixture until the container is two-thirds full. Don't overfill, as a lack of airspace will cause too much powder to be ejected when you squeeze the bottle.
Shake your container and then use it to squeeze a very thin layer of borax in places where roaches like to hide. Apply only enough powder to be just visible to the naked eye, as roaches will avoid large piles and clumps. Place the powder in small cracks and crevices near moisture and warmth where roaches hide, such as inside electrical outlets, in cracks between cabinets, around baseboards and wherever plumbing pipes and walls meet, including under sinks. Remember to spread some of the borax under and behind kitchen appliances such as stoves, refrigerators and dishwashers as well.
Borax is effective as long as it stays dry. Replace your borax dust only if it gets wet or you can no longer see the application.
To make your own borax roach bait, Toxic Free North Carolina recommends mixing together the borax powder, sugar, cornstarch, onion and water to make a paste. Roll the paste into small balls and place 2 or 3 balls into each sandwich bag.
Place the open bait bags in areas where you have seen roaches and in places they like to hide, such as under appliances and sinks. Make sure the bait ball is tucked where children and pets won't find it.
Replace the bait periodically when it has been consumed or has dried out.