How to kill cockroaches

Here is a simple recepie time and my tested to get rid of cockroaches.
Take equal quantity of refined wheat flour and Boric acid powder( also called boric powder) ,add a bit of milk and good amount of sugar,roll it into balls and keep it at the dark and marshy places in your home (especialy kitchen ) where your expect raoches to grow most!
I was helpless coz of roaches growth in my kitchen and not a single medicine was good enough as after a while roaches were getting immune to it ....then someone suggested me this and now there is not a single unwanted guest in my kitchen now for months.
BORIC ACID POWDER is a white colored powder very cheaply and easily available on medical /chemists shops and is also used to keep your feet free from any bacterial or fungal growth ...
Try it and comment it ,how effective it was....