I will say this is effective and can keep cockroaches away from your kitchen and other areas. But the most important thing is how clean you keep your full house.
Especially kitchen and bathroom as in this place cockroaches crawls lot. Use Laxmzn rekha chalk and make line or round circles all around the needed area Within hours you would see cockroaches dying or running. But its better that you do it at night and other morning your can clean all the surface and dead insects.
But if you have too much cockroaches problem then repeat this chalk treatment after two weeks or so. Now many insect killing sprays are also available, but this chalk is odorless and does not cause any allergy also. I have learn it from my mother.
After using this chalk keep it at a place where kids cant reach. Laxman rekha comes only for Rs. 25, anyone can buy it.Also if you mix phenol and dettol together and mop the floor with this liquid, you will find less crawling insects.