Removing Roaches. Occasionally I buy roach motels, that has a sticky substance inside a cardboard box, that make the roaches unable?

probably sexual attractant.

roach pheromones that humans cannot smell.

ditto for the mice in your other question.

Get a small bottle of boric acid at the drug store, or a large bottle of Roach-Pruf at the hardware store. Take a small amount on the tip of a spoon and blow it in the general direction of any place you have seen a roach, any crack in a baseboard, and under sinks. Not in open floor areas or cupboards.

The powder sticks to a roach's shell and dissolves the waxy coating so they dehydrate. They carry it back to the nest and pass it around and it wipes out the entire nest. One application is usually enough.

Usually sexual pheromones are used.  

Roach bait gel or combat bait.