The poplar borer (Saperda calcarata) and flathead poplar borer (Dicerca tenebrica) are common insects in natural forest stands around Grande Prairie.  The most visible sign is the damage they cause to poplar and aspen trees, boring large holes that then weep sap that stain the bark a dark brown. The larvae remain inside the trees feeding for two to five years before pupating and then emerging as adults to mate and lay eggs. High populations of this insect may significantly weaken or stress trees, particularly if they are already under drought stress.  Heavily infested trees become a blow down risk in high winds.

Plants Affected

Symptoms

The first signs of this insect will be sap weeping down the side of the tree, staining the bark a dark brown color. Upon closer inspection you will see holes drilled into the bark with sawdust and frass at the entrance or on the ground. Heavy woodpecker damage on your tree may also indicate the presence of these borers.

Controls

Cultural (Non-chemical) Controls:

  • Open-growing and lone trees are more susceptible to attack. Plant trees in shaded locations or in a stand to help them withstand attack more readily.
  • Remove brood trees - trees that are heavily attacked and serve only to infest other nearby trees.
  • Burn or bury removed trees immediately - larvae will continue to feed and may complete their lifecycle in stored firewood.
  • Do not plant Swedish columnar aspen.  These are short-lived trees prone to a variety of insects or disease.  For hedge or screen recommendations, contact Parks Operations at parks@cityofgp.com.

Biological Controls:

  • As this is a native insect, several natural predators and parasites exist to help keep populations in check.
  • They can kill up to 40% of eggs and 65% of larvae in some areas.
Adult Poplar Borer
Poplar Borer Larva
Heavy borer damage with sawdust at base of tree
Adult flathead poplar borer