Natural Resource Conservation


Land Stewardship Program

"The Dirty Dozen": PA's 12 Worst Invasives

These are 12 species, of many, that are posing the most serious threats to the native plants, animals and natural communities of the natural landscape of western PA. WPC is focused on identifying and managing for these species on our natural areas. Please use the form to report any of these species on our natural areas.

Purple Loosestrife (Lythrum salicaria, L. virgatum and varieties)

Purple Loosestrife

Garlic Mustard (Alliaria petiolata)

Garlic Mustard

Japanese knotweed (Polygonum cuspidatum and Fallopia japonica)

Japanese knotweed

Bush Honeysuckles (Lonicera maackii, L. morrowii, L. tatarica and L. x bella)

Bush Honeysuckles

Autumn Olive, Russian Olive (Elaeagnus umbellata and E. angustifolium)

Autumn Olive

Japanese stiltgrass (Microstegium vimineum)

Japanese stiltgrass

Multiflora rose (Multiflora rose)

Multiflora rose

Mile-a-minute weed (Polygonum perfoliatum)

Mile-a-minute weed

Eurasian water-milfoil (Myriophyllum spicatum)

Eurasian water-milfoil

Zebra mussel (Dreissena polymorpha)

Zebra mussel

Hemlock Woolly Adelgid (Adelges tsugae)

Hemlock Woolly Adelgid

Gyspy Moth (Lymantria dispar)

Gyspy Moth

For more information and photos, go to:

A List of Aquatic Exotic Animals & Plants
Invasive Species Initiative
Mid-Atlantic Exotic Pest Plant Council
DCNR Invasive Exotic Plant Tutorial