A destructive pest threatening forests
What is it?
Spongy moth (EGM; Lymantria dispar dispar) is an invasive and destructive pest that poses a risk to deciduous and coniferous tree species.
Trees at risk
Impacts
- A single spongy moth caterpillar can eat one square metre of leaves in a season
- Repeated defoliation makes trees susceptible to other pests and diseases, and can eventually lead to tree death
- Defoliation in orchards can increase vulnerability to agricultural pests and diseases and can negatively impact farm stock
- Loss of species in natural areas can affect biodiversity and forest wildlife
Life-Cycle

Eggs: Tan-coloured and can be found on tree trunks, bark, or other hard surfaces. Egg masses are about 4 cm and contain 100- 1,000 eggs.
Larvae: Charcoal grey with a double row of five blue and six red dots on its back. This is the life stage that causes defoliation.
Adult females: Larger than males with white colouring and dark zig-zag markings. Adult females are flightless.
Adult males: Greyish-brown with dark markings and can fly and survive about one week, mating with several different females.
How to manage Spongy Moth
CAUTION: Spongy moth caterpillars have long hairs that can cause skin irritation or allergic reactions for some people. For safety, use gloves while handling caterpillars.
Report sighting of Spongy Moth to:
EDDMapS Ontario: 1-800-563-7711 or www.eddmaps.org/ontario
Canada-wide: www.invasivespeciescentre.ca/report-a-sighting