VIU Milner Gardens and Woodland

What are the large webs in trees occurring in late summer?

Question: What are the large webs in trees occurring in late summer?

Answer: The Fall webworm or Hyphantria cunea, feeds on a variety of deciduous trees especially native alder, willow and bitter cherry, and tends not to be a serious pest in home gardens.   

These webs are unsightly rather than causing actual damage, and the webs are often too high to be clipped out of trees.

This pest is a light-coloured caterpillar covered with long hairs.

The webs tend to encompass the ends of branches.  The Fall webworms begin feeding in July and August, and their webs become apparent as they feed.

The more damaging northern tent caterpillars are active much earlier in April and May.

Remedial action:  Where possible cut the webs out of trees and dispose of them.

Birds and predatory insects also help control these pests.

Fall webworm or Hyphantria cunea Fall webworm or Hyphantria cunea Fall webworm or Hyphantria cunea

Photo courtesy: Phyllis Fafard.

Reference:  For more information on these pests, see Linda Gilkeson:  Natural Insect, Weed and Disease Control, 2006, Trafford Publishing.

For gardening questions in the growing season, contact the Gardening Advice Line.

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