Mulch and other decaying organic matter can actually be counter-productive in getting rid of pests. On site, Adam describes how insects will burrow into it during the winter to stay warm, and eventually make their way into your home.
Here we have an example of a lot of decaying organic matter on the ground. This harbors the insects. It's winter. They're looking for a place, a warmer place, to thrive and actually to burrow down over winter. Having vegetation like this or mulch chips or pine straw around the foundation of your house draws the insects from your yard to your home. They’ll, over winter here, set up right in the soil and eventually, when the spring hits and they start breeding, these insects end up going right up underneath your siding and giving you pressure inside your home, going in through those gaps that you see right on the wall.