There are many things that you can do yourself. For example, say you have a German Cockroach problem in Middleburg, FL. German Roaches must have water to survive. Eliminating sources of water can reduce populations and aid in the control results by the professional exterminator. In other words,1) look for different conditions that are conducive for the pest in question. 2) Figure out what they need to survive. 3) Take it away.
