Use a Borax Mixture
Borax, despite being easy to find and harmless to humans, is classified as an insecticide, and it proves effective at killing roaches. For the Borax method, there are two options. One is to dust the Borax powder around the house in a thin layer, using a brush if you like. Be sure to dust around appliances and against the walls, especially where there are any gaps or holes. Another, sometimes more effective option is to make a Borax paste. From a mixture of sugar, water and Borax into tiny balls. Roaches love sugar, and they will also bring some of the paste back into the nest for the young to eat. The Borax dehydrates the roaches, and if you keep reapplying over a period of a week or two, they should die off.
Use Baking Soda
Another great natural roach-killer is baking soda, which anyone can find in their kitchen. Like Borax, baking soda is environmentally safe and harmless to humans, but it is poisonous to roaches if eaten. As with the Borax, make a paste with water and sugar and rub the baking soda mixture all over the house, focuses on holes or crevices and anywhere roaches have been sighted. They won’t die immediately, so keep reapplying until no more roaches are sighted.
There are many household insecticide sprays that are readily available, and those recommended for killing roaches tend to be effective. While they are generally toxic and shouldn’t be inhaled or ingested, they are less toxic than chemicals used by exterminators. Some substances, such as liquid concentrates, can keep roaches away for several weeks before needing to be re-applied.
Seal Up Cracks and Crevasses
Whether you are trying to seal away or kill off a current roach infestation or prevent further ones, sealing up cracks anywhere you find them is one of the most effective options, as roaches can squeeze themselves through even tiny spaces. Look particularly for spaces that often hold food, such as in your pantry or between a countertop and wall, and often-forgotten spaces such as in the baseboards and behind appliances. For a sealant, caulk is often the best option, and a tube of caulk with a caulking gun will get the job done quickly.