A mixture of borax, sugar and flour kills both roaches and ants. The flour and sugar attract the insects, and the borax kills them. Cocoa powder is an effective substitute for the sugar.
Borax mixtures are also effective against silverfish. The boric acid content in borax damages the insects' outer skeletons, causing them to dehydrate. More expensive commercial insecticides also use boric acid. Water lowers borax's effectiveness, making it only suitable for dry locations.
While borax is less toxic than other insecticides, it is still mildly toxic. Users must ensure that children and pets do not have access to borax-based insect bait.