There is one proven way to get rid of the cockroaches and you can be sure that they will never return again and make your life bitter.
Here is the recipe which will end your problems with the cockroaches:
First you need to take 1 raw egg yolk and put 30-50 grams of boric acid powder in it. Mix until you get solid mixture. From this mixture make balls with a diameter about 1cm. Wait until gets dry for about an hour and pour them all over the house in visible places and corners.
Make sure that the kitchen and the bathroom have special attention. Do not forget that the place should be visible, not from your point of view but from the point of view of the insect. Parts of shelves, racks, closets, kitchen cabinets too and all that is above your eyes.
This interesting ball disguised with boric acid, the cockroaches will not feel but she will come out to it from curiosity. When the cockroaches touch the ball with its mustache will die or it will have infernal itching. It will not be able to warn its other brothers insects because it will be unable to move.