Radio Script
2000

__________________

Mining Leaves
__________________

Don't have RealAudio player? Download free software.

INTRO: You're not alone if you've noticed that the leaves on many of the aspen trees around Alaska's Interior look a bit strange this year. Our own Arctic Science Journeys Radio producer Doug Schneider gets to the root of the problem in today's report.

STORY: If you haven't already noticed, take a look around the next time you're out in the woods. You'll see leaves with gray streaks forming intricate patterns where there should be the rich green color of chlorophyll. These days, such leaves are hard to miss. Marta Mueller is a pest control expert at the University of Alaska Cooperative Extension Service. She says the patterns are the work of tiny insects called leaf miners.

MUELLER: "Leaf miners is a general term for an insect that feeds in the middle of the leaf. You've got two layers of leaf epidermis that help protect the inside of the leaf. And inside the leaf you've got a layer of nice green cells, their chlorophyll. And so people around Fairbanks and other parts of the state are noticing that their leaves are turning gray, and that there are these strange little tracks, like something has been mining the leaf."

There are hundreds of different leaf mining insects in North America. Some are flies, while others are beetles and moths. In Alaska's Interior, the leaf miner munching on aspen leaves is actually a brown moth in its larval stage. Hatched from eggs laid on the surface of the leaf, the larva burrows into the leaf where it finds the chlorophyll it needs to grow into a caterpillar.

MUELLER: "The egg hatches and the little larva burrows between the layers of the leaf. So, what's actually doing the damage is a caterpillar. A small caterpillar, maybe a quarter of an inch long. Sometimes you can see them in the leaf and sometimes you can't. And this little caterpillar just goes back and forth along inside the leaf, deriving its energy from the chlorophyll. Later on in the summer, the larva will drop out of the leaf and pupate and become an adult moth."

Mueller says that unless the leaf miner infestation is severe and lasts for several years, it's rare that the tree or plant would suffer serious damage. Rather than trying to control them, Mueller recommends enjoying the intricate patterns the insects make in the leaves.

MUELLER: "Most of the time people are just curious. What is causing this intricate design? I'm thankful for that because I can tell people that this is something they can enjoy and be amazed at. There's no reason to control them."

OUTRO: This is Arctic Science Journeys Radio, a production of the Alaska Sea Grant Program and the University of Alaska Fairbanks. I'm Doug Schneider.

For more information visit these web sites:

Alaska Cooperative Extension Service

Leaf Mining Insects

Birch Leaf Miner

Thanks to the following individual for help preparing this script:

Marta Mueller, Integrated Pest Management Technician
University of Alaska Fairbanks
Alaska Cooperative Extension Service
Fairbanks, Alaska 99775-8155
PH: 907-474-2428
Email: ftmrm@uaf.edu