National Invasive Species Awareness Week is February 23-27, 2026. Invasive species are plants or animals that take over a region in which they did not originate. They may be introduced to a new region intentionally, such as for gardening or landscaping purposes, or accidentally, for example by hitchhiking on goods being shipped from one continent to another. They dominate their new ecosystem through their growth characteristics, like prolific seed production, and/or a lack of natural population controls such as predation or herbivory. Invasive species reduce biodiversity and the health of their new ecosystems. The United States Department of Agriculture estimates that the cost of invasive species to the economy is over $26 billion per year since 2010.
Invasive species impacting our South Central Pennsylvania landscape include bush honeysuckle, multiflora rose, bamboo, garlic mustard, and privet. Last year alone, volunteers removed 600 cubic yards of invasive shrubs and 4,500 gallons of invasive herbaceous plants! Here are some other invasive species that are threatening our natural lands and keeping Lancaster Conservancy Forester Eric Roper up at night:
1. Beech Leaf Nematode (Litylenchus crenatae mccannii)
The beech leaf nematode is native to Asia. It impacts American beech trees in all life stages, damaging buds and newly formed leaves and disrupting the photosynthesis cycle, forcing the affected trees to tap into energy stored in their roots to create new buds and leaves. Within about three to 10 years, the nematode causes the tree to deplete its energy reserves and die.
Dying beech leaves affected by beech leaf nematode (Photo by Eric Roper)2. Sericea Lespedeza (Lespedeza cuneata)
Sericea lespedeza, also referred to as Chinese bush clover, is a member of the legume family that is native to Asia. It’s a prolific seeder, producing 1,000-1,500 seeds per plant, which can then be viable in the soil for 20 years or more. It has an allelopathic quality that allows it to “steal” nitrogen from other surrounding plants, giving it a competitive advantage.
Sericea lespedeza (Photo by Eric Roper)3. Kudzu (Pueraria montana var lobata)
Kudzu is colloquially referred to as “the vine that ate the South.” A plant that is native to east Asia, it was introduced to the U.S. by the Soil Conservation Service as a means of controlling soil erosion. Kudzu can grow more than a foot in a single day, and this rapid growth allows it to quickly take over a site and choke out native vegetation.
Kudzu (Photo by Eric Roper)4. Chinese Yam (Dioscorea polystachya)
Chinese yam, a native of east Asia, is an aggressive perennial vine which forms dense mats that suffocate native vegetation. This species was originally planted as a food and medicinal crop, but it quickly escaped cultivation and began invading other natural spaces. It is especially quick to colonize open or disturbed sites. It reproduces through underground tuberous roots as well as aerial bulbils (small potato-shaped tubes that grow above the ground), which makes controlling this species especially challenging. Birds and other wildlife eat the aerial bulbils, adding to the spread of this invasive plant when they defecate. And when pulling the plant out of the ground, it is important to make sure to remove the entirety of the plant, or the resilient tuberous roots will allow the species to persist.
Chinese yam (Photo by Eric Roper)5. Wavyleaf Basketgrass (Oplismenus undulatifolius)
Wavyleaf basketgrass is a shade-tolerant, fast-growing perennial grass native to Europe and Asia. Locally, it has been documented at Lancaster County Central Park, and a population of this plant was discovered at Kellys Run Nature Preserve in 2024. It is widely distributed across Maryland after being first found there in 1996, but is not yet considered well established in Pennsylvania, so the Pennsylvania Department of Conservation and Natural Resources is working hard with public and private landowners to control the spread of this species. This prolific seeder produces “sticky” awns that can spread by attaching to shoes, clothes, and pets (dogs in particular can be involved in spreading the seeds). The growth and plant characteristics of this species make mechanical control difficult – consult with an expert before removing it.
Wavyleaf basketgrass (Photo by keisotyo, CC BY-SA 3.0 http://creativecommons.org/licenses/by-sa/3.0/, via Wikimedia Commons)Ecological restoration of Lancaster Conservancy preserves involves managing invasive species like these, giving our ecosystems the best chance to thrive. Learn more about restoration on Conservancy preserves in Eric’s recent Nature Hour presentation:
If you’d like to help Lancaster Conservancy fight invasive species and care for our nature preserves, learn how you can volunteer with us at lancasterconservancy.org/volunteer. Also, learn how you can support native wildlife on your property and in your community at lancasterconservancy.org/habitat!