Common Pennsylvania Pests

Tree and Shrub Pests

There are many things to consider when keeping our arboretum (or your trees) healthy and vibrant. And just as our arboretum is a diverse collection of trees, so too are the pests that call it home. Below you can find links to some of the leading experts on tree health and some brief descriptions of the pests.

Infamous Insects

While all pests can cause issues for trees in one way or another, a few species have received a little more "press" recently. Species like the Emerald Ash Borer and the Spotted Lanternfly have become more of a pressing and prevalent pest since they have been introduced to the area. Below is a little more information about these new and frequently talked about invasive species.

Emerald Ash Borer

The Emerald Ash Borer is a small and slender insect with iridescent green color. The larval stages of these species are very destructive, boring paths under the bark of ash trees, giving the species its common name.

Spotted Lanternfly

The spotted lanternfly is a pest species native to Asia and was recently introduced to Pennsylvania. It is a leaf hopping species that can fly short distances, but its primary means of locomotion is hopping or jumping from plant to plant. The species can stunt the growth or even kill trees by sucking the sap out of plants.

Spotted Lanternfly

Other Pests To Look Out For

Bagworm

Here are some helpful links and guides:

Penn State Extension: Bagworm Factsheet

Morton Arboretum: Bagworms

USDA Forest Service: Bagworm PDF

Birch Leafminer

Here are some helpful links and guides:

Penn State Extension: Birch Leafminer Factsheet

USDA Forest Services: Birch Leafminer PDF

UMass Extension: Birch Leafminer

Boxelder Bug

Boxelder Bug Image

Here are some helpful links and guides:

Penn State Extension: Boxelder Bug Factsheet

Morton Arboretum: Boxelder Bugs

UMass Extension: Boxelder Bug

Bronze Birch Borer

Bronze Birch Borer Image

Here are some helpful links and guides:

Penn State Extension: Bronze Birch Borer Factsheet

Morton Arboretum: Bronze Birch Borer

Missouri Botanical Gardens: Bronze Birch Borer

Brown Marmorated Stink Bug

Brown Marmorated Stink Bug Image

Here are some helpful links and guides:

Penn State Extension: Brown Marmorated Stink Bug Factsheet

Missouri Botanical Garden: Brown Marmorated Stink Bug

USDA: Combatting the Brown Marmorated Stink Bug

Carpenter Ants

Carpenter Ants Image

Here are some helpful links and guides:

Penn State Extension: Carpenter Ants Factsheet

Morton Arboretum: Carpen ter Ants

USDA Forest Services: Carpenter Ants PDF

Cooley Spruce Gall Adelgid

Here are some helpful links and guides:

Penn State Extension: Cooley Spruce Gall Adelgid Factsheet

USDA Forest Service: Cooley Spruce Gall Adelgid PDF

Morton Arboretum: Cooley Spruce Gall Adelgids
Cottony Maple Scale

Here are some helpful links and guides:

Penn State Extension: Cottony Maple Scale Factsheet

Morton Arboretum: Cottony Maple Scale

Ohio State University Extension: Cottony Maple Scale and its Managment
Eastern Tent Caterpillar

Here are some helpful links and guides:

Penn State Extension: Eastern Tent Caterpillar Factsheet

Missouri Botanical Garden: Eastern Tent Caterpillar

USDA Forest Service: Eastern Tent Caterpillar PDF
Elm Leaf Beetle

Here are some helpful links and guides:

Penn State Extension: Elm Leaf Beetle Fact Sheet

Morton Arboretum: Elm Leaf Beetle

Missouri Botanical Garden: Elm Leaf Beetle

Elm Spanworm

Elm Spanworm Image

Here are some helpful links and guides:

Penn State Extension: Elm Spanworm Factsheet

St John's: Elm Spanworm

Elongate Hemlock Scale

Here are some helpful links and guides:

Penn State Extension: Elongate Hemlock Scale Fact Sheet

USDA Forest Service: Elongate Hemlock Scale PDF

UMass Amherst: Elongate Hemlock Scale
Eastern Spruce Gall Adelgid

Here are some helpful links and guides:

Penn State Extension: Eastern Spruce Gall Adelgid Factsheet

UMass Amherst: Eastern Spruce Gall Adelgid

Bartlett Tree Experts: Spruce Gall Adelgids
European Fruit Lecanium

Here are some helpful links and guides:

Penn State Extension: European Fruit Lecanium Factsheet

UC IPM: European Fruit Lecanium
European Pine Sawfly

Here are some helpful links and guides:

Penn State Extension: European Pine Sawfly Factsheet

Missouri Botanical Garen: Pine Sawfly

Morton Arboretum: Pine Sawflies
European Pine Shoot Moth

Here are some helpful links and guides:

Penn State Extension: European Pine Shoot Moth Factsheet

Missouri Botanical Garden: European Pine Shoot Moth

Forest Service USDA: European Pine Shoot Moth
Fall Webworm

Here are some helpful links and guides:

Penn State Extension: Fall Webworm Factsheet

Forest Service USDA: Fall Webworm PDF

Missouri Botanical Garden: Fall Webworm
Fletcher Scale

Here are some helpful links and guides:

Penn State Extension: Fletcher Scale Factsheet

FERA Plant Health Portal: Fletcher Scale Factsheet
Galls on Oak

Here are some helpful links and guides:

Penn State Extension: Galls on Oak Factsheet

Missouri Botanical Garden: Gouty, Horned, and other Twig Galls
Gypsy Moth

Here are some helpful links and guides:

Penn State Extension: Gypsy Moth Factsheet

Bartlett Tree Experts: Gypsy Moth PDF

Missouri Botanical Garden: Gypsy Moth
Hemlock Woolly Adelgid

Here are some helpful links and guides:

Penn State Extension: Hemlock Woolly Adelgid Factsheet

Bartlett Tree Experts: Hemlock Woolly Adelgid PDF

USDA Forest Service: Hemlock Woolly Adelgid
Honeylocust Plant Bug

Here are some helpful links and guides:

Penn State Extension: Honeylocust Plant Bug Factsheet
Leaf Galls on Maple

Here are some helpful links and guides:

Penn State Extension: Leaf Galls on Maple Factsheet
Magnolia Scale

Here are some helpful links and guides:

Penn State Extension: Magnolia Scale Factsheet

Morton Arboretum: Magnolia Scale Information
Mimosa Webworm

Here are some helpful links and guides:

Penn State Extension: Mimosa Webworm Factsheet
Native Holly Leafminer

Here are some helpful links and guides:

Penn State Extension: Native Holly Leafminer Factsheet

Missouri Botanical Gardens: Native Holly Leafminer Information
Obscure Scale

Here are some helpful links and guides:

Penn State Extension: Obscure Scale Factsheet
Oystershell Scale

Here are some helpful links and guides:

Penn State Extension: Oystershell Scale Factsheet

US Forest Service: Oystershell Scale Information
Peachtree Borer

Here are some helpful links and guides:

Penn State Extension: Peachtree Borer Factsheet

Missouri Botanical Gardens: Peachtree Borer Information

US Forest Service: Peachtree Borer Factsheet
Pine Needle Scale

Here are some helpful links and guides:

Penn State Extension: Pine Needle Scale Factsheet

US Forest Service: Pine Needle Scale Factsheet

Bartlett Tree Experts: Scale Insect Factsheet

Missouri Botanical Gardens: Information on Pine Needle Scale
Spruce Spider Mite

Here are some helpful links and guides:

Penn State Extension: Spruce Spider Mite Factsheet

Missouri Botanical Gardens: Info on Spruce Spider Mites

Bartlett Tree Experts: Spider Mite Factsheet
Tuliptree Scale

Here are some helpful links and guides:

Penn State Extension: Tuliptree Scale Factsheet

Bartlett Tree Experts: Tuliptree Scale Factsheet

Missouri Botanical Gardens: Magnolia and Tuliptree Scale: Factsheet
Twospotted Spider Mite

Here are some helpful links and guides:

Penn State Extension: Twospotted Spider Mite Factsheet

Bartlett Tree Experts: Spider Mite Factsheet

US Forest Service: Spider Mite Fact Sheet
White Pine Weevil

Here are some helpful links and guides:

Penn State Extension: White Pine Weevil Factsheet

US Forest Service: White Pine Weevil
Yellow Necked Caterpillar

Here are some helpful links and guides:

Penn State Extension: Yellow Necked Caterpillar Factsheet

More Information