The invasive jumping worm population is threatening Minnesota’s forests.  Officials say the worms are traveling throughout the state in mulch applied in neighboring gardens.  The worms turn healthy soil into a substance that resembles cat litter or coffee grounds.  Officials say the worms can do even more damage in the forests.  The Department of Natural Resources says prevention is the best method for dealing with the worms, especially by not moving plants from one area of the state to another.