What Leaves Finely-Ground Wood Piles in Front of My Tree?

Wood-boring Insects

• Wood-boring insects are usually the culprits when a mass of finely ground wood piles in front of a tree. These pests attack a wide variety of ornamental trees and shrubs with the specific type of borer dependent on the species of plant. Mature moths and beetles attracted to the tree lay eggs on and produce the immature larvae -- borers -- that feed on the wood of the tree and cause significant and sometimes fatal damage.

Symptoms

• The finely-ground wood piles are a collection of sawdust, wood chips and borer frass -- excrement -- that falls from the tree as the larvae "bore" into the bark, creating tunnels and feeding on the wood. In addition to the pile of sawdust, a tree filled with holes in the bark offers an additional clue that it is facing an onslaught of a particular borer. Additionally, a gummy substance will leak from the bark or base of the trunk.

Damage

• The borers limit the ability of a tree to distribute water and sap and a girdling -- strangling -- of limbs and branches occurs. The death of limbs, an overall loss of tree vigor and eventual death of the specimen will take place if the borer attack is especially severe or if it continues unmanaged for several seasons. Borers rarely inhabit healthy trees. Instead they are drawn to those that are older and suffering from stress due to drought, winter injury or a multitude of other weaknesses.

Management

• Dependent on the size of the tree and degree of infestation, handpicking the borer larvae can minimize the population and damage on smaller trees. However, the majority of borers overwinter on the tree, and a new generation of the pests begin the feeding process anew in the spring. Insecticides are helpful in managing borers on most species of tree. The exact insecticide and application instructions will differ dependent on the tree and borer species.