Lymantria dispar moth

What is an Invasive Species?



Invasive species--plants or animals not native to a particular area--can seriously damage ecosystems. Here’s how.

Invasive species develop when a species is introduced to a new environment without a natural predator and rapidly reproduces to all but take over the area. An invasive species can wreak havoc on an ecosystem by suffocating the natural growth of indigenous species, leading to a depleted population and even extinction. There have been a number of famous invasive species across the world in human history, many of which still exist today.

Humans have moved species of plants and animals around, introducing them to new habitats for as long as we’ve been on Earth. However, not every species introduced to a new habitat becomes invasive. Many plants and animals in foreign environments die off. It is the species that can reproduce in new ecosystems that live on to become invasive species. Introduced species multiply too quickly and become invasive or are accidentally released and go on to become invasive. Some examples in the US include Burmese pythons, introduced to Florida as part of the wild pet trade, and Lymantria dispar, a species of moth that was accidentally released in the US and now decimates trees of their leaves, leaving them vulnerable to disease.

This doesn’t mean that every non-native species is invasive. In fact, many introduced species have become commonplace in the US. Think of petunias, which blossom in gardens nationwide, or tomatoes, which the US produces and consumes en masse. Those are both examples of non-native species that are not invasive. It’s important to differentiate between invasive non-native species and non-invasive non-native species. It is also important to note that the term “invasive species” has a nativist bias and can demonize and even lead to the death of non-native species in any given area.

While most people think they will never be responsible for introducing an invasive species to an area, it is a risk that accompanies many human behaviors. Traveling and bringing back a favorite piece of fruit, for example, can introduce species like the Mexican Fruit Fly, which threatens dozens of species of produce grown in the US. The Asian tiger mosquito is native to southeast Asia but has spread all over the world when eggs are in pools of water inside shipments of tires. Like the Burmese python or the Tegu lizard, many invasive species were initially introduced to an environment as pets. When these wild animals escape or are set free into a foreign ecosystem, they can quickly reproduce and dominate at the expense of other species in the ecosystem.

Keep these examples in mind when traveling or adopting a new pet, as you could be contributing to the global invasive species issue. And, of course, never purchase a wild animal as a pet, no matter how cute they may be. Admire them in their natural habitats or rescue a pet in need of a home instead.

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