Why care about invasive species? Because they are everywhere, in your yards and gardens (unless you’ve conscientiously removed them), bordering your walking paths and parks, they keep you company on all escapades, they’re ornamental trees planted, they creep in and ravage a farmer’s land, and on top of all that—they simply are not enticing to your livestock, your insects, not your native birds who require insects for fuel during long-distance flights, nor your deer. Deer love natives (preferentially feeding on natives over invasive species), and we all know deer populations in the Chesapeake Bay watershed are wildly out of control. With increased use of native species by our animals, coupled with invasive species’ intense ability to out-compete natives, we see a predictable decline in biodiversity and therefore a disruption to the complex and co-evolved food web. In other words, an ecosystem trapped in a horror film.

I know what you all are thinking—some definitions please! What are invasive species? Are they the same as non-native species? All invasives are non-native, but not all non-native species are invasive. Confused? Me too. Except think spooky, scary, think of invaders. While both were intentionally or accidentally moved from their native home ranges and into a new environment, invasive species usually represent the havoc wreckers, the toxic occupiers. Examples of the non-native and non-invasive species overlap include many agricultural crops.

According to the Plant Invaders of Mid-Atlantic Natural Areas field guide, they describe an invasive species as one that causes economic and/or environmental harm to the health of plants, animals, and humans. Invasives take great satisfaction in colonizing environments without natural predators, parasites, or pathogens that’d normally keep a species like them from explosive spreading. As a contributor to diseases in humans, natural disasters, crop damage, degraded infrastructure, and native species extinction, invasive species cost the United States an average of 120 billion per year.

Let’s go back to the beginning. Now that we know why they’re in our spooky season newsletter, let’s dive into their origin story. Let’s go back to as early as the 1500s. Colonialism brought colonizers. Feral pigs were one of the first to come over. English ivy (Araliaceae) was introduced in 1727, now covers most, if not all, of the United States.

Globalization and the export and import of goods and services furthered the introduction of invasive species. With the transport of materials in and out of Asia, some invasives were spread accidentally, such as Japanese stiltgrass (Microstegium vimineum), originally used as packing material in Japan. Invasives from Asia thrive in the United States as we share similar climates and do not possess the natural predators and pathogens to control growth as Asia, where these species originated, does. Mile-a-minute or devil’s-tail tearthumb was introduced to Pennsylvania in the 1930s from Asian. This vine smothers native plants, blocking precious sunlight from their reach. Let’s not forget how Kudzu vine (Pueraria montana), Autumn olive (Elaeagnus umbellata), honeysuckle (Lonicera), porcelain berry (Ampelopsis glandulosa), princess tree (Paulownia tomentosa), Japanese barberry (Berberis thunbergii), and wineberry (Rubus phoenicolasius) among many others, were introduced purposefully by the U.S. government. In many cases, these plants were introduced as ornamental plants, to “restore” old mining areas, reduce erosion, or provide wildlife habitat, all of which proved frighteningly destructive. The Soil Conservation Service paid farmers in the 1930s to plant Kudzu to counteract soil erosion caused by deforestation. Instead, invasives such as kudzu push out and block native plants, topple trees with their sheer weight, deter native animal consumption, and some, such as Amur honeysuckle’s chemical toxin,s actually harm native insects, kill or cause behavioral changes in amphibians, and harbor ticks, increasing mammals’ susceptibility to illness.

Fast forward, 2014. Spotted lanterflies (Lycorma delicatula) were first introduced to the United States from China in 2014. The lanternfly will feed on and kill native vines, hardwood trees, hops, and crops. Dangerous for its honeydew mold left behind post feeding, the lanternfly, in this story, is our villain who colludes with other villains.

Tree-of-heaven (Ailanthus latissimus), a preferred host of the lanternfly, thrives in harsh conditions—it is drought-tolerant and can even be found growing out of rocky surfaces like pavement. Like the lanternfly, there are too many of them. Tree-of-heaven forms colonies or “fraternal stands” that produce the chemical ailanthone, acting as an herbicide, which effectively deters growth of nearby native plants.

A healthy ecosystem is vital to maintaining natural cycles and therefore ecosystem services such as reducing erosion and runoff into the Chesapeake Bay watershed, providing clean air and water, shade, and habitat. Healthy ecosystems are made up of native species that’ve co-evolved with their environment for thousands of years, so that no one species dominates over any others. This perfectly balanced system requires checks and balances, sways and rocks and steadiness. A wide diversity of native plants, for example, hosts an increasing number of different species of herbivores such as rabbits, which are preyed upon by foxes. Plants also host a variety of pollinators, such as bees and butterflies, to bring further life to other plants. They host insects that are calorie-dense and nutritious enough to support a variety of small native predators such as frogs, birds, and bats, notably known to reduce mosquito population sizes.

Bats the stereotype for bad omens, signify that classic horror film trope; they’re blood-crazed and bonkers, and did I mention their unpredictable flight pattern? Creepy. But in this story, they aren’t vampires or rabies, they’re our heroes.

Present day, 2025, researchers from various universities discover lanternfly DNA in bat guano. Bat poop! Imagine, a small (mostly not thought about), native predator to save the day. Not only are they wildly unappreciated for their mosquito-controlling abilities, but now, lanterflies as well. Bats are a keystone species, which means they have a disproportionately positive effect on ecosystem health. Not only do they control insects, but they also pollinate the very crops we survive off of. Unfortunately, white-nose syndrome and habitat degradation of forests and tree cavities have led to their decline.

Bats prefer adult lanternflies, which usually take form between July and September. Will we notice a significant decline in the invasive species by October 31st? Can they make a dent in this wildly uncontrollable population of lanternflies? Bats cannot do it alone. Saving bats is a priority, and while the Alliance for the Chesapeake Bay is working hard to restore forests, those at home in cities may benefit this Halloween by installing bat boxes to create more functional habitat. Happy Halloween, everyone!