Here in Miami,I used to have a hard time with "Palmetto Bugs", which is what Realtors? call the giant flying roaches that infest the Sunshine State. Every morning I would find them zipping around my sink, and at night I could flip on the lights and see a major Midnight Surprise. Then I bought some Echols Boric Acid tablets, which claim to be 40% Boric Acid, $1.29 for 4 oz. and now I rarely see any sort of roach. Before that I tried the Boric Acid powder (somewhat useful), Chinese Boric acid chalk (somewhat less useful that the previous) and various kinds of aerosol sprays (expensive, stinky and seemed only to make the roaches disoriented and less shy).
I also occasionally saw some common German cockroaches, the sort known as esquilines in Mexico, but I have seen nary a one since I scattered tablets about.
Boric Acid is said to be effective because of a fatal flaw in cucaracha physiology: they cannot fart. The Boric acid gives them gas, and, unable to expel the gas, it simply blows up inside them and they die a flatulent death. A day or two after scattering the Boric Acid tablets, you will see them legs pointing toward Heaven on the floor, occasionally slowly moving their appendages. If you step on one, they make a popping sound like a teenager playing with bubble wrap.I consider roaches one of God's more unwise ideas, but at least He made them mostly mute and ugly as sin, so we will not feel so bad about murdering them. I am truly grateful that they do not resemble teensy Panda bears, unicorns or sea otters.