One of the main rules to cockroach control is to find and treat ALL of the active harborages. You can t just treat surfaces because cockroaches spend most of their time in cracks and crevices. You want to treat where they live which means you want to treat in the hard to reach areas. Wall voids, junction boxes, conduit systems and even ceilings are great places for cockroaches to harbor. In treating ALL active harborages you must look beyond the obvious.
Roaches infest dark, warm and damp locations.
Apply bait gel in spots the size of a dime or in a bead. The general rule is more frequent, smaller gel applications are more effective than fewer, larger placement. The bait must be placed along walls, in corners or in cracks or crevices. Roaches are usually found in dark, warm and damp areas around food and water sources. Apply bait to potential points of insect entry such as eaves, sills and expansion joints.