Organic and inorganic mulches provide higher moisture conditions and buffering of extreme temperatures. Termites seek those same conditions. Termites feed on spring wood and do not feed on bark. Comparing eucalyptus, hardwood or pine bark mulch with a control diet of white birch, survivorship rates for mulch-fed termites was significantly lower than in the controls in recent lab studies at Maryland. The study concluded that foraging termites would not heavily feed on organic, wood-based mulches.
In field studies, termite foraging activity was measured beneath mulches. (Eucalyphus, hardwood, and pine bark) plus pea gravel with bare ground as a control. The termites were observed traveling within the mulch itself to get from the soil to a wood source, confirming observations that mulches might provide a bridge between the soil barrier treatment and wooden structures. The microhabitat beneath the pea gravel mulch was more favorable to termite activity compared to the organic mulches. Thus the study recommended keeping mulches 18 inches from structures and not using excessive mulch levels so termites (and other occasional house invading pests like earwigs, centipedes, crickets, and sow bugs) would face a more exposed drier habitat immediately adjacent to a structure or building. Thanks to Sue Barton and the University of Delaware Cooperative Extension for this article taken from Ornamentals Hotline.