Heartwood

• Heartwood, which is the interior portion of a tree, is sometimes thought to be toxic to termites. These pests prefer sapwood, the outer part of the tree. Whether the mulch will repel termites largely depends on whether it is derived from heartwood or sapwood.
  
  

Aroma

• The aroma of red cedar mulch may help repel some other types of insects such as crickets, roaches and moths. Small chips of this wood can be placed inside a dresser drawer or wrapped in a cloth bag and hung inside a closet to help repel these pests.
  
  

Risks

• Termites often feed on wood mulch made from black oak, pine or cherry. It is not known if this material attracts termites to a home or provides enough food so they do not need to invade it. The University of Florida Extension reports that more research is necessary.