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United States Department of Agriculture

Agricultural Research Service

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Can the Stem Borer Help Conquer the Green Invader?

A plant called Old World climbing fern is acting somewhat like a big bully that has just moved into your neighborhood. The climbing fern has moved into Florida from overseas, and is thriving in the Sunshine State. The trouble is, it grows so fast and becomes so thick that it easily smothers other plants, like a thick green mat. The plants under the mat don't get the sunlight that they need, and may die.

But climbing fern isn't just a problem on the ground. It is a problem above the ground, too. As you can probably tell by its name, climbing fern loves to climb and climb. Climbing fern plants on the ground form long stems that climb up cypress trees, for example. Up and up they go, into the tops of the trees.

Why is that a problem? If a fire breaks out, it can use the climbing fern stem as its ladder. Up and up the fire can climb, burning the tree as it goes. That makes the fire more dangerous to the tree than if it didn't have the climbing fern clinging to it.

Agricultural Research Service (ARS) scientists are trying to help trees and other plants in the Everglades fight back against climbing fern. Help may come from thousands of miles away, in Australia. Scientists there are doing tests of a helpful insect that damages climbing fern. The insect is called a stem borer. Like many other insects that you might know about, the stem borer looks very different at different stages of its life.

During one stage, it is a long, skinny worm that chews a hole into climbing fern stems. Then, it chews out a snug little home for itself inside the stem. That might seem uncomfortable to you, but apparently it suits the stem borer just fine.

A stem borer isn't very big. So how can this little insect damage a big climbing fern plant? Scientists like Matthew Purcell, who is the director of the ARS Australian Biological Control Laboratory in Brisbane, Australia, can tell you the answer. When the skinny worm tunnels into a climbing fern stem, it cuts off the flow of food and water that the stem needs. Much of the stem dies. That's how an insect that isn't very long can kill a very, very long climbing fern stem.

Scientists like Matthew Purcell are studying the stem borer very closely to see if it would be a good idea to bring the insect to Florida and put it to work in the Everglades and other places where climbing fern is an invader.

But the scientists first need to make sure the stem borer attacks only Old World climbing fern. It would be a mistake to bring it to Florida if it attacked some other plant, such as someone's favorite roses! That's why the stem borer must pass many tests. In a few years, scientists will have their answer. If the stem borer passes all of those tests, it may become a new hero of the Everglades!

--By Marcia Wood, Agricultural Research Service, Information Staff.

Things To Do To Learn More

Want to learn more? Ask a parent, teacher, or older friend to help you with the following activities.

Scientists give plants scientific names to avoid confusion about the identity of the plant. Plants also have nicknames, called common names. "Old World climbing fern" is a nickname or common name for this plant's scientific name, which is Lygodium microphyllum. Whew! What a mouthful!

  • See if you can find the scientific name of another plant by looking up the plant by its common name in an encyclopedia.

Climbing fern is an invasive species. An invasive species can be a plant, an animal, a microbe, or other form of life that has moved from where it belongs do someplace else, and is causing harm.

  • See if you can find out about another invasive species that is causing problems in your state. Learn why it is a problem.

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Last Modified: 8/12/2016
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