Invasive plants are non-native to a region, grow rapidly, spread aggressively, and displace native plants and wildlife, thus negatively impacting ecosystems. The impact of invasive plants has been linked to critical population declines in native birds, pollinators and other insects, increased erosion impacting water quality, and inhibiting successful forest regeneration and natural succession. Additionally, invasive plants cause economic and human health concerns by impacting industries such as agriculture, recreation, and tourism and can increase risks associated with Lyme disease and other illnesses.
While many of these species are planted to add beauty and ornamental value to a landscape, numerous unsuspecting homeowners and commercial landscapers may not realize the negative ecological and economic impacts these species can have on nearby natural areas.
Numerous landowners across Pennsylvania are incorporating native plants into their landscapes; however, plenty of invasive plants still exist in countless yards, gardens, and other portions of privately owned properties. The Pennsylvania Invasive Plant Replace-ive Program is a new initiative that will give residents the option to remove invasive trees and shrubs from their property and replace them with native trees. Doing so will help reduce the likelihood of these species becoming unwanted “escapees” into neighboring properties, parks, and forests, and native trees help diversify the urban landscape.
Invasive species are non-native plants, animals, and other organisms that cause harm when introduced to new ecosystems. In Pennsylvania, invasive species are increasingly becoming a major threat to native plants, animals, and entire ecosystems. According to the Pennsylvania Governor’s Invasive Species Council, there are now over 300 invasive species established across the state, and more arrivals are expected in the coming years.
In this article, we will examine some of the most problematic invasive species in Pennsylvania, the threats they pose, and what is being done to manage these unwelcome invaders.
Top Invasive Animal Species in Pennsylvania
Pennsylvania has been invaded by numerous non-native animal species that compete with and prey upon native wildlife. Here are some of the most destructive invasive animals in PA:
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Spotted Lanternfly: This invasive planthopper from Asia is causing serious damage to agricultural crops and ornamental trees. First detected in Berks County in 2014, it has now spread to 34 counties and threatens Pennsylvania’s $19 billion agriculture industry.
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Northern Snakehead This vicious predatory fish from Asia has been found in some Pennsylvania waterways It competes with native fish and can devastate aquatic ecosystems
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Emerald Ash Borer Native to Asia, these metallic green beetles have killed millions of native ash trees across Pennsylvania since their detection in 2007.
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Gypsy Moth: Since the 1860s, outbreaks of these invasive moths from Europe have repeatedly defoliated forests across Pennsylvania. Extensive damage occurs during outbreaks.
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Quagga & Zebra Mussels: These prolific filter-feeding mussels have invaded all of Pennsylvania’s major waterways. They disrupt ecosystems, damage infrastructure, and spread disease.
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Feral Swine: Also called wild boars, these escaped domestic pigs degrade natural areas, prey on native wildlife, and spread disease. Their populations are growing across Pennsylvania.
Most Problematic Invasive Plants in Pennsylvania
In addition to animals, Pennsylvania is battling numerous invasive plant species that outcompete and smother native flora:
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Tree of Heaven: Native to China, these rapidly growing trees in the sumac family form dense thickets that overwhelm native vegetation across the state.
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Mile-a-Minute Weed: Introduced from Asia as a horticultural plant, this sprawling vine has vicious barbs and smothers native plants. It occurs in at least 33 counties.
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Kudzu: The “vine that ate the South” is increasingly problematic in Pennsylvania. Kudzu grows up to 60 feet per year, enveloping and killing trees and native plants.
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Japanese Stiltgrass: This aggressive Asian grass invades forests, fields, and roadsides. It crowds out native plants and can dominate forest understories.
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Japanese Knotweed: A large, dense plant from Asia that escapes cultivation. It pushes out stream-side vegetation and alters natural ecosystems.
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Purple Loosestrife: With its beautiful purple flowers, this European wetland invader outcompetes native plants that provide better wildlife habitat.
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Common Reed Grass: Dense stands of this tall European grass dominate wetlands, crowding out native plants. It occurs across two-thirds of the state.
Impacts of Invasive Species in Pennsylvania
From disrupting native ecosystems to damaging the economy, invasive species cause a multitude of harmful effects in Pennsylvania:
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Reduced Biodiversity: Invasives compete with native species for resources, and can drive declining native populations towards extinction.
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Degraded Habitats: Invaders like kudzu and purple loosestrife form mono-cultural stands that severely degrade natural habitat quality.
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Forestry Damage: Pests like the emerald ash borer and gypsy moth have decimated native tree species like ash and oak across Pennsylvania forests.
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Agricultural losses: The spotted lanternfly invasion is a severe economic threat to vineyards, orchards, and many other agricultural sectors across Pennsylvania.
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Recreational impacts: Invasive aquatic plants like hydrilla can choke waterways, making boating, fishing and swimming difficult.
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Infrastructure damage: Prolific zebra mussels clog pipes and other infrastructure, with control costs up to $500 million annually across the Great Lakes region.
Management and Control of Invasive Species
With invasive species wreaking havoc across Pennsylvania, federal and state agencies are taking steps to manage and control their spread, including:
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Prevention: Restricting imports and pathways of potentially invasive species, and early detection of new arrivals before they spread. Public education on invasive risks is also key.
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Mechanical control: Cutting, mowing, hand-pulling and carefully using herbicides when necessary to remove invasive plants. Trapping and culling programs target animal invaders.
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Biological control: Using specialized insects, diseases or other natural enemies from the invasive species’ native range to control populations. Must be carefully researched for safety.
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Legislation: Pennsylvania regulates the import, sale and possession of certain high-risk invasive plants and animals. More legal authority is likely needed.
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Partnerships: Cooperation between government agencies, conservation groups, land managers, and the public is required for effective invasive species management.
Looking Ahead: The Expanding Threat of Invasive Species
With increasing global trade and climate change, Pennsylvania will likely continue seeing more invasive arrivals that threaten our state’s native biodiversity and economy. Preventing new invasions will be crucial. Ongoing research, education, monitoring, and integrated management efforts are needed to minimize the impacts of both new and established non-native species. Concerted action from government, land managers, researchers and the public will give Pennsylvania’s vulnerable native ecosystems a fighting chance against these relentless invaders.
What is the Pennsylvania Invasive Replace-ive Program?
At its core, the Pennsylvania Invasive Replace-ive Program will provide education by distributing native trees at five regional events to replace removed designated invasive trees and shrubs. The program and distribution events complement the Pennsylvania Native Species Day, an initiative of the Pennsylvania Governors Invasive Species Council, that will be celebrated on May 20th.
The 2025 Invasive Replace-ive distribution events are scheduled to take place in northwest (Erie), northeast (Scranton), southeast (Darby), southwest (Greensburg) and central (Carlisle) Pennsylvania. Any Pennsylvania resident can register for a distribution event to adopt up to five native trees as replacements for removing one or more qualifying invasive trees or shrubs anytime between 2020 and now. Photographic proof of removal can be uploaded via each distribution events respective site registration form. Native tree replacements will be on a first-come, first-served basis while supplies last.
What invasive trees and shrubs qualify?
The following lists indicate which invasive trees and shrubs can be removed by property owners or others wishing to participate in the program. We encourage the removal of selected, high priority (Tier 1) species when possible; however, other woody invasive species are also acceptable. Removal should follow recommended practices, such as those included in the links below. The removed invasives can be on the registrants property or elsewhere if participants have landowner permission to remove them.
Invasive Species of Pennsylvania Waterways
FAQ
What are 3 invasive species in PA?
Almost 60 invasive aquatic animals are identified as of greatest concern for Pennsylvania, from highly impactful emerging species, like zebra mussels, quagga mussels, and northern snakehead, to not-yet-present but potential major concerns, including silver carp and bighead carp.
What is the #1 most invasive species?
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Feral Cats (Felis catus):Domestic cats that roam freely or are abandoned have a significant impact on native wildlife, preying on birds, mammals, and reptiles.
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European Starling (Sturnus vulgaris):Introduced to North America from Europe, they compete with native birds for resources and can damage crops.
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Cane Toad (Rhinella marina):Introduced to Australia to control cane beetles, they proved to be a disaster, as they are poisonous and outcompete native species.
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Burmese Python (Python molurus bivittatus):A large, non-native snake that has established populations in Florida, posing a threat to native wildlife.
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Introduced to North America for aquaculture, they outcompete native fish species and can damage infrastructure.
What fish are invasive in Pennsylvania?
- Bighead carp (Hypophtalmichtys nobilis)
- Black carp (Mylopharyngodon piceus)
- Crayfish (all species) except when they are either transported: …
- European rudd (Scardinius erythropthalmus)
- Quagga mussel (Dreissena bugensis)
- Round goby (Neogobius melanostomus)
- Ruffe (Gymnocephalus cernuus)
Is Tree of Heaven invasive in Pennsylvania?
Learn about the invasive tree-of-heaven, commonly found in Pennsylvania, and how you can use it to help control another invasive species, spotted lanternfly. Tree-of-heaven is an invasive tree species found in much of the United States.
How many invasive species are in Pennsylvania?
The Pennsylvania Governor’s Invasive Species Council has identified about 300 invasive plants, insects, pathogens, and animals as having the greatest current or potential negative impacts for Pennsylvania. This list is provided to inform development of regulation, policy, and education to protect our agricultural and natural resources.
Does Pennsylvania have an invasive species management program?
The Pennsylvania Governor’s Invasive Species Council announced that a pilot test of a regional invasive species management program will launch this summer. This follows the findings from the first statewide survey of impacts from invasive plants, insects, pathogens, and animals.
Are invasive animals a problem in Pennsylvania?
Almost 60 invasive aquatic animals are identified as of greatest concern for Pennsylvania, from highly impactful emerging species, like zebra mussels, quagga mussels, and northern snakehead, to not-yet-present but potential major concerns, including silver carp and bighead carp. These must be prevented from being introduced.
What is the Pennsylvania invasive species webinar?
Pennsylvania has identified over 150 invasive plants, insects, pathogens, and animals that significantly impact both the environment and agricultural production, resulting in annual economic losses amounting to hundreds of millions of dollars. The Pennsylvania Invasive Species webinar is committed to addressing this critical issue.
Are invasive plants swallowing Pennsylvania?
“Invasive Plants are Swallowing Pennsylvania”. PennLive, The Patriot-News. Retrieved October 15, 2019. invasivespecies.gov United States Government.
How are invasive species grouped?
Invasive species are often grouped by threat levels that vary from county to county from very high impact to remarkable increased growth. The species below are by no means comprehensive and are listed in type order rather than level of threat