A good way to kill roaches without chemicals is to use a boric acid-based roach bait ball, according to Good Housekeeping. A bait ball is created using four ingredients: boric acid, flour, sugar and shortening.
To create this bait, combine 1/4 cup of shortening and 1/8 cup of sugar until the mixture is creamy. In a separate bowl, mix together 8 ounces of boric acid and 1/2 cup of flour. Add these dry ingredients to the shortening and sugar mixture. Add water to form soft, doughy balls. Place the balls where roaches are seen, keeping them away from children and pets. Roaches do not die immediately using this method.
An alternate option for getting rid of roaches naturally is to spray the bugs with a combination of soap and water, which smothers the insects, as stated by Mother Nature Network.