Small Actions, Big Impact: Five Ways to Help Stop Invasive Species

Invasive species are a global problem with local impacts. In fact, they pose a significant threat to Pennsylvania's natural areas, agriculture, and forestry sectors. These species can cause a range of negative ecological and economic impacts, including biodiversity loss, habitat degradation, altered ecosystem dynamics, increased management costs, reduced recreational opportunities, and risks to human health. Invasive species include plants, animals, fungi, and other organisms that are introduced—either intentionally or accidentally—outside their native range, and cause, or are likely to cause, harm to the environment, economy, or human health. Examples of high-profile Pennsylvania invaders include spotted lanternfly, spongy moth, flathead catfish, zebra mussel, jumping worms, European starling, hydrilla, Japanese stiltgrass, tree-of-heaven, and Callery pear.

Thinking about the volume and distribution of invaders and their impacts in the Commonwealth can be overwhelming, but there are simple actions you can take to help stop the spread of invasive species. The most effective way to combat invasive species is to prevent their introduction and stop the spread of those already present. You can do this by:

1. Make informed choices when selecting plants or pets.
2. Dispose of garden waste responsibly and never release bait, aquarium fish, or pets into the wild.
3. Clean your boots, gear, and boats before moving between recreation areas.
4. Ensure you don't accidentally transport pests, weeds, and pathogens when traveling ("Don't Pack a Pest").
5. Look for opportunities to volunteer to help remove invasive species and educate others about the threat.

A list of links to resources will be provided at the end of this article.

1. Make Smart Choices When Selecting Plants or Pets

The primary pathways for the introduction and spread of invasive plants and animals are horticultural escapes and the pet trade. Most of the traits that make a plant desirable for landscaping, such as fast growth, hardiness, low maintenance, resistance to pests, and the ability to thrive in a variety of conditions, are often the same traits that enable it to become invasive (Figure 1). Most animals moved outside their natural habitats to be sold as 'exotic' pets, stay in captivity, and never form wild populations. However, some escape or are intentionally released, and in some cases, they become invasive species that threaten native wildlife and ecosystems^[1]. Many pets are "tank-busters," starting out small and growing much larger than expected, while others can live for decades and require a long-term commitment from their owners (Figure 1). Some of these owners might not be prepared for the time, cost, or effort involved in long-term care or may not be able to care for animals that grow to be larger than expected.

When selecting plants for your yard or garden, plants native to Pennsylvania are always the best option. However, if you opt for nonnative plants, select well-behaved, non-invasive varieties with a proven track record of safe use in your region, including sterile cultivars. Before planting, be sure to consult local invasive species lists from trusted sources such as Penn State Extension, the PA Invasive Species Council, or the PA Department of Conservation and Natural Resources to make informed decisions. And if you're considering a nonnative pet, take the time to research and plan carefully to ensure you are up for the commitment and can provide lifelong care. You can find more information at "Don't Let it Loose," a resource provided by the US Fish and Wildlife Service.

2. Properly Dispose of Garden Waste and Never Release Bait or Pets into the Wild

The introduction of invasive species often occurs through everyday actions, but they can be prevented with a few mindful practices. Dispose of garden waste responsibly and avoid tossing unwanted plants, soil, or clippings over fences, into vacant lots, or into nearby woods. Invasive plants can easily take root and spread in new environments. For noxious weeds or potentially invasive plant material, double-bag them and place them in the trash to prevent further spread. Similarly, never dump aquarium fish, plants, or water into lakes, rivers, or other natural bodies of water, as they may contain nonnative species or pathogens.

Releasing unwanted pets into the wild is also harmful—many cannot survive, while others may thrive at the expense of native species. Instead, rehome pets through responsible adoption networks or surrender them to a shelter or appropriate facility. Allowing cats to roam freely outdoors is a debated topic, but research clearly shows that free-ranging domestic cats have significant impacts on native wildlife. In the United States alone, they are estimated to kill between 1.3 and 4.0 billion birds each year. As cats are not a natural part of most ecosystems, their presence can disrupt local biodiversity and threaten vulnerable species. To protect wildlife and keep your pet safe, it's best to keep cats indoors. For a healthy compromise, consider building a portable or permanent "catio"—an enclosed outdoor space that allows your cat to safely enjoy fresh air, sunshine, and the sights and sounds of nature.

3. Clean Your Boots, Gear, and Boats Before Moving Between Recreation Areas

Programs such as "Play Clean Go^®" powered by NAISMA and The Pennsylvania Fish and Boat Commission's "Check. Clean. Drain. Dry."  promote responsible outdoor recreation by encouraging people to remove plant and animal hitchhikers from clothing, pets, gear, vehicles, trailers, and boats. These efforts aim to prevent the introduction and spread of invasive species during recreational activities (Figure 2). Before traveling to new areas, inspect and clean your trailers, off-road vehicles, and recreational vehicles, and clean your horse's hooves. Clean hiking boots, clothing, and gear before you enter or leave an area, and use boot brush stations where available or handheld boot brushes to help remove seeds and pathogens. Stay on designated roads and trails when visiting state and national parks.

While enjoying watersports, fishing, or other activities on the water, take time to thoroughly inspect your boat, trailer, and fishing gear before leaving any body of water (Figure 2). Remove and leave behind any plants, mud, or aquatic organisms to prevent unintentionally transporting them to new locations. Some species may live for months in water that has not been removed, so be sure to drain water from all equipment before leaving the area you are visiting. Do not release unused bait into the waters you are fishing. Dump unused bait in a trash can. Even if your gear looks clean, it's important to clean it thoroughly. Finally, allow all gear and equipment to dry completely before entering a new water body to help stop the spread of aquatic invasive species.

4. "Don't Pack a Pest" When Traveling

When traveling, it's important to avoid unintentionally carrying invasive species like insects, seeds, or plant diseases on your clothing, gear, or souvenirs. For international travel, you can check the "Don't Pack a Pest" website before traveling to find out what can and cannot be brought into the United States, and look for signage at the airport for information while traveling. You may also see detector dogs in the international terminal that play a critical role by helping to intercept hidden agricultural pests and prohibited items at points of entry (Figure 3).

On a local scale, inspect your vehicles to avoid transporting invasive hitchhikers like the spotted lanternfly (Figure 4). Egg masses of invasive insects can resemble mud and often hide in wheel wells or undercarriages. When camping, buy firewood where you plan to burn it, ideally within 10–50 miles, and look for certified heat-treated options. The "Don't Move Firewood" campaign promotes this practice to prevent spreading pests like the emerald ash borer (Figure 4). Leave any unused firewood at the campsite. By checking your belongings, cleaning your gear, and following travel guidelines, you can help protect both the places you visit and your own community from the damaging effects of invasive species.

Figure 4. An adult spotted lanternfly hitchhikes on a vehicle (Left). The public outreach campaign Don’t Move Firewood encourages people to “Buy it where you burn it” (Center). Stacks of firewood showing distinct S-shaped feeding galleries, a clear sign of emerald ash borer infestation. Credit: PA Department of Agriculture (Left); The Nature Conservancy, Don’t Move Firewood (Center); Troy Kimoto, Canadian Food Inspection Agency, Bugwood.org.

5. Volunteer to Remove Invasive Species and Raise Awareness About Their Impact

Volunteering and educating others about the dangers of invasive species are powerful ways to protect local ecosystems and prevent the spread of harmful plants, animals, and pathogens. By participating in community efforts such as invasive species removal events, habitat restoration projects, or educational outreach, you help reduce the impact of these species. Just as importantly, spreading awareness empowers others to act in their yards, neighborhoods, and workplaces. Many people unknowingly contribute to the spread of invasives, so education plays a key role in changing behaviors and building a broader culture of stewardship and prevention. Together, we can make a difference and stop the spread of invasive species in the Commonwealth.

For more information:

Invasion Pathways Webinar: This webinar discusses how invasive species are introduced and provides relevant examples.

How To Properly Dispose of Invasive Plant Species article

[1] Lockwood, Julie L., et al. "When pets become pests: the role of the exotic pet trade in producing invasive vertebrate animals." Frontiers in Ecology and the Environment 17.6 (2019): 323-330.

Peer reviewed by Dr. Patricia Prade, Horticulture Extension Entomologist, Penn State Extension.