On this page you will find a list of common pests of trees in Ontario sorted by tree species.
The main features of the habits and lifecycles of pests are outlined in order to better understand the reasons for taking steps in any effort to control a specific pest. Unless otherwise indicated, all pests discussed in this publication are considered to be native to Ontario.
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| Tree Specie | Common Pests | Pest Details (habits, lifecycles, illustrations & control Methods) |
|---|---|---|
| Alder | Woolly alder aphid | PDF, 148KB |
| Apple | Apple-and-thorn skeletonizer Eastern tent caterpillar Apple scab |
PDF, 237KB |
| Arborvitae | (see Cedar) | |
| Ash | Ash flower gall Fall webworm |
PDF, 240KB |
| Basswood | (see Linden) | |
| Birch | Birch leafminer Birch skeletonizer Bronze birch borer Yellownecked caterpillar |
PDF, 263KB |
| Boxelder (Manitoba maple) | Boxelder bug Boxelder twig borer Boxelder leaf blight |
PDF, 119KB |
| Butternut | (see Walnut) | |
| Catalpa | Comstock mealybug Catalpa leafspot Verticillium wilt |
PDF, 127KB |
| Cedar, eastern white | Cedar (Arborvitae) leafminers Cedar-apple rust (see Juniper rusts) |
PDF, 170KB |
| Cherry | (see Peach) | |
| Elm | Elm bark beetles Elm leaf beetle European fruit lecanium Spiny elm caterpillar Dutch elm disease |
PDF, 286KB |
| Euonymus | Euonymus scale Euonymus webworm Crown gall |
PDF, 233KB |
| Hawthorn | Pear sawfly Hawthorn leaf blight |
PDF, 132KB |
| Honeylocust | Honeylocust pod gall | PDF, 113KB |
| Horse-Chestnut | Whitemarked tussock moth Horse-Chestnut leaf blotch |
PDF, 241KB |
| Juniper | Juniper scale Juniper webworm Juniper blight Juniper rusts |
PDF, 186KB |
| Larch | Larch casebearer Larch sawfly |
PDF, 187KB |
| Lilac | Lilac borer Lilac leafminer Oystershell scale Powdery mildew |
PDF, 155KB |
| Linden | Cankerworms June beetles Linden looper |
PDF, 168KB |
| Locust | Locust borer Locust leafminer Locust twig borer |
PDF, 284KB |
| Maple | Cottony maple scale Maple gall mites Maple leafcutter Maple trumpet skeletonizer Norway maple aphid Saddled prominent Anthracnose Dieback of hardwoods Nectria canker |
(see Boxelder for Manitboa maple) |
| Mockorange | Mockorange leafminer |
PDF, 103KB |
| Mountain Ash | Mountain ash sawfly Pearleaf blister mite Rose chafer Fire blight |
PDF, 312KB |
| Oak | Gypsy moth Oak galls Oak lace bug Oak leafshredder Oak skeletonizer Twig pruner Armillaria root rot |
PDF, 659KB |
| Peach, Plum, Cherry | Lesser peachtree borer Peachtree borer Black knot |
PDF, 123KB |
| Pine |
Eastern pine shoot borer |
PDF, 1.52Mb |
| Plum | (see Peach) | |
| Poplar | Forest tent caterpillar Poplar petiolegall aphid Poplar sawfly Poplar vagabond aphid European poplar canker Hypoxylon canker |
PDF, 369KB |
| Spruce | Cooley spruce gall adelgid [aphid] Eastern spruce gall adelgid [aphid] Spruce bud scale Spruce budworm Spruce needleminer Spruce spider mite Yellowheaded spruce sawfly Other spruce sawflies Spruce canker |
PDF, 851KB |
| Walnut | Walnut caterpillar Yellow leaf blotch |
PDF, 122KB |
| Willow | Giant bark aphid Imported willow leaf beetle Poplar-and-willow borer |
PDF, 174KB |
| Yew | Black vine weevil | PDF, 129KB |
Return to Table of Contents (Common Pests of Trees in Ontario)
