By the time you see one cockroach, there are probably dozens, if not hundreds, somewhere nearby. The sooner you begin a cockroach elimination program, the more successful you will be in eliminating the pests.
Prevention and Identification
There are two things that you need to do before you can effectively get rid of roaches. The first is to eliminate the reason the roaches have invaded your environment. Roaches seek food and water, and it does not need to be plentiful for roaches to survive. Crumbs, drippy faucets, trash cans, sink traps, even a forgotten candy wrapper are inviting to roaches. Clean, thoroughly clean, every inch of your home. If the roaches cannot find food or water, they may leave. Plug or caulk any crack or space you think they may be coming in from and make sure your windows and doors have tight seals.
Second, catch them in sticky traps. There are five common species of cockroaches in North America, each particular to what food and environment they seek. Set out roach sticky traps in places you have seen them, dark areas such as under sinks and in closets, or wherever you think they may be getting in. By catching them in a sticky trap, not only are you killing some of them and discovering where they are coming from, but also you can now determine what species you have to better target your elimination efforts (see Reference 1).
Baits and Poisons
Cockroaches adapt and mutate quickly, which is why most roach sprays you buy soon stop working. Boric acid or borax is very effective in most cases. The boric acid will cling to the roach's legs. The roach ingests it and within three to 10 days will be dead. The roach will also carry the poison back to the nest, thus killing more roaches than a spray will. Put the boric acid along base boards, under sinks and the refrigerator and anywhere you think the roaches are coming in. It will take some time for the boric acid to work, but it will. Continue to supplement the boric acid treatment with strategically placed sticky traps. It has been reported (see Resource 1) that a product called Harris Roach Tablets is very effective in getting rid of roaches.
You may live in an apartment complex or may have recently moved into a home that is heavily infested with cockroaches. Home remedies may not be as effective in those circumstances, and a professional exterminator needs to be called in. Professionals have access to much stronger chemicals to get rid of roaches. A monthly, routine spraying schedule may be needed, particularly if you live in an apartment, because you have no control over your neighbors. If you begin to see roaches reappear after the routine spraying, tell the professional so he can change to a different chemical.