Tree Pests

Tree Pests

Aspen leafroller
This year like in in the previous year there is many poplars being affected by the aspen leafroller. They roll themselves in leaves for protection and to pupate. The caterpillar is green with a brown or black head and is about 3/4” to inch long. Damage to the trees is temporary and will not kill the trees. To control them you need to spray a dormant oil in the early spring as the leaf protects them from spraying.

Birch-aspen leafroller

Poplar borer
Signs of this insect are large holes with sawdust or shredded wood coming out of the holes and piled at the base of the trunk. Sap leaks down and stains the bark brown attracting other insects. The insect prefers trees with a diameter of about 4”, in low density stands. The insect has a long life cycle, extending over 3 to 4 years.


  • Inspect your poplars several times during the growing season and look for any signs of damage
  • Pest control products like ‘Garden Protector’ can be used as a trunk and foliage spray prior to the borers penetrating the wood
  • If the borers enter the wood, control is difficult. A number of gardeners have been quite successful applying Knock Down aerosol insecticidal spray directly into the entry holes on the tree trunks.

If a tree is infested, remove it and destroy the wood by chipping or burning it before May or June, preventing larvae from maturing.

Poplar Borer

Yellow-headed spruce sawfly
Produces a green larva with a prominent yellow or amber coloured head and thin grey stripes running the length of the body. An insecticide application is generally the most effective method of control.

Yellow-Headed Spruce Sawfly

Spruce budworm
Majority of the feeding is done by mid-to-late June. The mature larvae are about ¾” to an inch long, with a black head and a reddish brown body that is lighter on the sides and has two rows of whitish spots on the back. Pupation occurs at feeding sites or on the lower branches. The moths emerge in late June to early August and lay their eggs in masses (15-50 eggs) on the underside of the needles in mid-to-upper crown and then hatch in about 10 days.

Spruce Budworm

Other Insects of Concern:

Aspen Defoliators

Pests of Small Fruit