Spongy moth and other defoliators

Learn about common caterpillars that strip the leaves from trees and shrubs, and what you can do to protect your property.

Think your trees have a forest health problem? Contact a local arborist for confirmation and treatment options.

Pests

Large black beetle with white spots on back and long black and white antennae.

Asian long-horned beetle

An invasive wood borer.

Light coloured caterpillar in webbing on aspen leaf.

Aspen twoleaf tier

An insect that mainly feeds on aspen trees.

Light coloured caterpillar eating birch leaf.

Birch casebearer

An invasive insect that feeds on birch and alder.

Light coloured caterpillars on birch leaf.

Birch skeletonizer

An insect that feeds on the leaves of birch trees.

Cedar needles showing browning caused by cedar leafminer.

Cedar leafminer

A group of insects that feeds on the insides of cedar foliage.

Dark brown beetle on larch stem.

Eastern larch beetle

A beetle that burrows under the bark of tamarack (larch) trees.

Large shiny green beetle on ash leaf.

Emerald ash borer

An invasive beetle that kills ash trees.

Two dark caterpillars on leaf.

Forest tent caterpillar

An insect that eats the leaves of hardwood trees.

Cose up of hemlock woolly adelgid nymphs.

Hemlock woolly adelgid

An invasive insect that causes hemlock trees to lose their needles.

Light brown caterpillar with white spots on pine needles.

Jack pine budworm

An insect that eats jack pine needles.

Larch casebearer larvae feeding on larch needles.

Larch casebearer

An invasive insect that hollows out larch needles.

Light green caterpillar with black head on leaf.

Large aspen tortrix

An insect that eats the leaves of hardwood trees like aspen and birch.

Light brown and white striped caterpillar feeding on pine needles.

Pine false webworm

An invasive insect that eats the needles of pine trees.

Hairy brown caterpillar with white spots down it’s back on leaves.

Satin moth

An invasive insect that damages poplar and willow trees.

Two dark, hairy caterpillars with blue spots at the front and red spots at the back eating a leaf.

Spongy moth

An invasive insect that feeds on hardwoods.

Brown caterpillar on spruce branch.

Spruce budworm

An insect that eats spruce and fir needles.

Diseases

Honey mushrooms associated with armillaria root rot.

Armillaria root rot

A fungal disease that kills trees.

Stem of large beech tree with beech bark disease.

Beech bark disease

An invasive fungal-insect complex that kills beech trees.

Beech leaves showing dark striping caused by beech leaf disease.

Beech leaf disease

A new-to-Ontario disease, possibly caused by a worm-like nematode.

Pine needles showing yellow and black damage from needle blight.

Brown spot needle blight

A disease that damages pine trees.

Stem of butternut tree showing canker damage.

Butternut canker

An invasive disease that kills butternut trees.

Dogwood leaves with brown spots caused by anthracnose disease.

Dogwood anthracnose

An invasive disease that damages dogwood trees.

Large elm tree with dead leaves at the top.

Dutch elm disease

An invasive disease spread by a beetle that kills elm trees.

Oak tree with dead leaves.

Oak wilt

An invasive fungal disease that kills oak trees.

Birch leaves turning yellow and brown from septoria fungus.

Septoria leaf spot of birch

A fungal disease common in wet years.

Fungal fruiting bodies of white pine blister rust on pine branch.

White pine blister rust

An invasive disease that kills white pine, especially young trees.

Severe weather conditions

Conifer trees blown over.

Blowdown

Localized tree fall caused by extreme wind/weather events.

Aerial view of forest with patches of brown trees.

Drought damage

Browning caused by prolonged periods of dryness.

Trees bent over a road by snow.

Snow damage

Heavy snow loads weighing down trees, often breaking tops and branches.

Aerial view of forest plantation with brown trees.

Winter browning

Needle browning or loss caused by warm weather in winter followed by extreme cold weather in spring.