Baking soda and sugar is a tried-and-tested natural way to kill roaches. The pests are attracted to the smell of the sugar, while the baking soda ensures they won't survive.
Mix equal parts of baking soda and white granulated sugar, advises the article, "10 Uses for Baking Soda" on This Old House. Steve Tvedten, who holds certifications in pest management, suggests adding powdered yeast or powdered vitamin C to the mixture -- 45 percent baking soda, 45 percent sugar and 10 percent powdered yeast.
Place the mixture in small plastic containers, used jar lids or small plates and position these wherever you have spotted roaches, such as under your kitchen sink or in the garden. Cockroaches like to hide in dark corners, so place your bait underneath kick plates, behind electrical outlets and around plumbing pipes, advises the article "Cockroaches" by Evergreen Pest Control.
Check your containers every couple of days, and fill them up if necessary.