Q. I know you recommend bark mulches around trees to help in water retention. However, there are negatives to consider such as cockroaches, bugs, etc.  I encounter lots of cockroaches in the ground when I have excavated in certain areas of our yard. Untreated wood chip mulch including pine needles and leaves A. I encourage the use of wood mulches more than bark mulches. Bark mulches seldom decompose much and add very little value to the soil. They are purely decorative. Wood mulches decompose easily in moist soils and add a lot of value to desert soils. Benefits of wood chip mulch You are absolutely right. Insects such as cockroaches are scavengers. Like many insects they like two things; water and a food source. This is why you frequently see tons of them inside irrigation boxes. They feed on plants and animal life that have died and help in its decomposition. Feeding on dead and animal life helps return organic life back to the soil. Cockroaches do not discriminate between dead plant or animal life whether it is inside the home or outside the home. They will enter the home if given the opportunity. Using a foundation spray Using a foundation spray or pesticide around the perimeter of the home and in valve boxes helps to keep them from entering our home. This is an insecticide spray barrier applied to the outside of the home at soil level and 12 inches above the soil. A good time to make this application is when temperatures begin to cool in the fall.  It also helps if you keep wood mulches away from the foundation of the home. There is no reason you need to apply wood mulches up to the foundation.