During Invasive Species Awareness Week, we ask the question, “What does it mean to be an invasive species?”, and “What can we do about them?” Fortunately, both questions are relatively easy to answer.
First we need to define Native Species. These are plants and animals that are indigenous to a local area and have specially adapted and co-evolved alongside wildlife and other plants, and climate.
Invasive species are introduced plants and animals (whether by accident or on purpose) who have established themselves in the new area AND cause ecological harm. Many plants were introduced for specific agriculture purposes such as food sources, hedgerows, ornamental value, or even as erosion controllers. Over time, many of these species grew out of control and became invasive. Some have no natural herbivorous predators, diseases, or ways to manage seed dispersal. Others are aggressive girdlers, meaning that as they climb trees, they suffocate them. Today, invasive plants and animals are considered some of the leading threats to biodiversity, as well as to our own health.
Many animals are introduced as globalization continues. They find their way aboard cargo ships, planes, and other vehicles, then get deposited far, far away from home. These are animals with no natural predators or diseases to manage populations and they turn from wonderful animal in their home country to invasive pest.
Below are some invasive animals in Pennsylvania, however they may be found throughout a large geographical region.
Spotted Lantern Fly (Lycorma delicatula)– These colorful jumping insects were originally native to China before making their way overseas on cargo ships. While many think they are beautiful, they can cause ecological harm by devastating fruit and ornamental tree populations. Yellow Jackets and invasive Praying Mantids have been seen eating Spotted Lantern Flies, which can help manage the population. Another way to manage them is to find the egg cases (which look like lines of mud) on trees in the winter and scrape them off into jars of alcohol.
Rusty Crayfish (Orconectes rusticus) – This crayfish was suspected of being used as live fishing bait, which then escaped into Pennsylvania waters. It’s a highly aggressive, large-growing crayfish, which outcompetes native, Eastern Crayfish. The Eastern Crayfish is digs holes and tunnels which provides homes for many native aquatic lifeforms that can’t dig on their own. As the Eastern is outcompeted, that tunnel habitat disappears. Rusty Crayfish also grow too quickly and too large for many standard crayfish predators to eat them, which means that their populations grows without check. By ensuring that any live bait is only used in areas where that bait is native to, or by using non-live bait, you can help ensure that fishing bait species don’t become invasive!
Japanese Beetle (Popillia japonica)– In their native ranges in Japan, these beetles are talented pest managers, however in PA, that is not the case. These invasive insects were introduced in the early 1900’s and have since run rampant, causing devastation to the agriculture industry – both commercially and in homeowner’s gardens! To get rid of them, simply hand-pick the adults off of the plants and put in a bucket of soapy water. If the adult has a white dot on it’s back (near the head), you can leave that one be. The white dot is a parasitic fly egg. When the egg hatches, it will consume the beetle, so allowing those adult beetles to live will ensure that the parasitic fly population also survives and continues it’s job as a pest manager.
Below are some invasive plants in Pennsylvania, however they may be found all over North America.
Japanese honeysuckle (Lonicera japonica) – This invasive honeysuckle is native to Eastern Asia, and was introduced to North America in the 1806. It is a rapid-growing vine that can strangle vegetation, and will out compete native plants for sunlight. Infestations can be controlled by mowing twice a year or just removal of vines by hand. Some wonderful alternatives are the Coral honeysuckle (Lonicera sempervirens) and the Pink honeysuckle (Lonicera hispidula).
Garlic Mustard (Alliaria petiolata) – Originally from Europe and parts of Asia, Garlic Mustard has prolifically spread in North America forest edges and shaded meadow areas. Their small flowers produce many seeds which are easily spread. The garlicky taste deters herbivores, so they don’t have a natural predator. As garlic mustard plants spread, herbivores turn to eating native plants, and as the number of native plants dwindle, so do those animal populations. Garlic mustard also prevents trees from forming beneficial connections with fungal mycorrhizae, which aids in nutrient sharing and communication between tree populations. Therefore, as garlic mustard populations increase, tree health decreases. Fortunately, these are easy to dig up by hand before they go to flower and spread seeds. Being able to make pesto and delicious foraged foods with their leaves is an added bonus!
Porcelain Berry (Ampelopsis brevipedunculata) – These are multicolored berries that bloom in the late fall, and are highly invasive. Originally from Northern China and Japan, porcelain berries were introduced to North America as an ornamental plant in the 1800s. This plant grows rapidly and abundantly, and it can quickly kill native plants by blocking out sunlight access. Removing these plants by their roots before their berries ripen will reduce the future growth of the plant!
Getting rid of invasive animals is a lot harder than getting rid of plants, however with many of the insect species, we can easily scrape away egg cases and quickly smoosh or drown them when we find them. Killing insects may be difficult to do, since people tend respect animal life in a different way than plant life. Fortunately, insects such as the invasive Japanese beetle don’t seem to like garlic and other alliums, so planting garlic around your garden may deter them. This doesn’t mean that the beetle is eradicated, but that they have ventured off to eat and breed in another location. Be mindful as you encounter these species and keep in mind that in their own homes, they are wonderful, but here they cause catastrophic damage to our ecosystems.
Cutting back, preventing seed-dispersal, burning, and digging up invasive plants can help to slow and mitigate their spread. Once the plants have been removed, many make delicious drinks, desserts, and side dishes! Some invasive species that are also edible include Garlic Mustard (seen here as a pesto), Wineberry, Autumn Olive, Japanese honeysuckle flowers, and Dame’s Rocket flowers.
Are you interested in learning more about creating and sustaining healthy ecosystems, both for plants and wildlife? Check out my upcoming in-person & virtual events! Visit my shop to find some conservation-themed merch. A portion of the proceeds supports habitat conservation efforts and invasive removals.