Non-Toxic Roach Killers
One highly effective roach killer that is entirely non-toxic is a gecko. Many people use geckos in their homes to get rid of cockroaches.
They release the geckos into their homes and allow them to roam freely, hunting down the cockroaches wherever they are. Once they have eradicated the infestation, they will start appearing out in the open, searching for more food, so you can capture them and place them in a terrarium.
This requires care and feeding once they kill all of the roaches, so this approach isn't for everyone Another non-toxic roach killer that you can make at home consists of mixing baking soda and sugar together. The sugar will lure the cockroaches out to eat it, and the baking soda will combine with the natural acids in their bodies and cause a fatal reaction.
Another, similar concoction is to combine baking soda, bacon grease, flour, sugar and some minced onions together into a sort of dough and leave that out for the roaches to find. This will kill them in the same manner as just sugar and baking soda mixed together, but has the added advantage of being easier to clean up.
You can also try spreading substances such as diatomaceous earth, epsom salts and bay leaves around your house, as these can both repel and kill the cockroach infestation. Cockroaches are extremely adept at surviving, so before you try any type of roach killing method, whether it's natural or chemical, be sure that you've roach-proofed your home by cleaning up any foodstuffs and open water containers that provide a source of nourishment for the infestation.
This is the only way to ensure that they don't come back once you've killed them all.