Ball Game Over?

Few things say springtime in America America like hearing the crack of a baseball bat at a neighborhood ballfield. But the wooden bats long used to play this national pastime may disappear. That’s because North American ash trees—the source of the most-commonly used wood to make bats—are being attacked by insects called emerald ash borers.

The company Louisville Slugger has made bats from ash wood for 135 years. But “in one to two years, we won’t have enough ash to fulfill demand,” says Brian Boltz, general manager of the company’s timber division in Pennsylvania. The problem began 17 years ago. That’s when people in southeast Michigan began noticing unfamiliar shiny green beetles on and around dead ash trees. After cutting through the trees’ bark, scientists saw zigzagging tunnels, called galleries, created by the insects. The beetles had eaten the trees alive.

Today, emerald ash borers have spread to 35 states and several Canadian provinces (see Bug Invasion). They’ve killed tens of millions of trees, and nearly 9 billion more are at risk. It’s the most destructive insect infestation in North American history—and it could spell the end of baseball’s most popular type of bat.

What sound says springtime in America? For many people, it’s the crack of a baseball bat at a neighborhood ballfield. Wooden bats have long been used for this national pastime. But these bats may disappear. That’s because most of the wood used for bats comes from North American ash trees. And these trees are being attacked by insects called emerald ash borers.

The company Louisville Slugger has made bats from ash wood for 135 years. But “in one to two years, we won’t have enough ash to fulfill demand,” says Brian Boltz. He’s general manager of the company’s timber division in Pennsylvania. The problem began 17 years ago. People in southeast Michigan started seeing strange, shiny green beetles on and around dead ash trees. Scientists cut through the trees’ bark and saw zigzagging tunnels. These galleries were made by the insects. The beetles had eaten the trees alive.

Today, emerald ash borers have spread to 35 states and several Canadian provinces (see Bug Invasion). They’ve killed tens of millions of trees. Nearly 9 billion more are at risk. It’s the worst insect infestation in North American history. And it could mean the end of baseball’s most popular type of bat.

The emerald ash borer is an invasive species. The beetle came to the U.S. from China in the mid-1990s. Scientists believe the insects hitched a ride aboard ships carrying crates made of infested wood. It took nearly a decade for anyone to realize that ash borers were here, allowing the insects to spread through forests unchecked.

“It’s very difficult to tell when a tree is infested by ash borers,” says Kathleen Knight, an ecologist at the U.S. Forest Service in Ohio who studies the insects. The sneaky beetles can stay hidden for years inside a tree without detection. “One of the first signs of infestation are woodpeckers feeding high up at the tops of trees,” says Knight. The birds love to gobble up the emerald ash borers’ larvae—the immature insects—living beneath tree bark (see Ash Borer Infestation).

After about two years, larvae go through a metamorphosis, or maturation into adults, and tunnel out of the tree. Adult ash borers then lay eggs in a different place on the same tree or on one nearby, starting the cycle all over again. Eventually, the tree becomes so damaged that it dies.

The emerald ash borer is an invasive species. It came to the U.S. from China in the mid-1990s. Scientists believe the insects arrived on ships carrying crates made of infested wood. No one knew the ash borers were here for nearly a decade. That allowed the insects to spread freely through forests.

“It’s very difficult to tell when a tree is infested by ash borers,” says Kathleen Knight. She’s an ecologist who studies the insects at the U.S. Forest Service in Ohio. The sneaky beetles can stay hidden for years. No one sees them inside a tree. “One of the first signs of infestation are woodpeckers feeding high up at the tops of trees,” says Knight. The birds love to eat the emerald ash borers’ larvae. These young insects live under trees’ bark (see Ash Borer Infestation).

After about two years, larvae go through a metamorphosis. They change into adults and tunnel out of the tree. Then they lay eggs in a different place on the same tree or on a nearby tree. That starts the cycle all over again. Over time, the tree becomes so damaged that it dies.

Scientists are trying many approaches to fight ash borers, says Knight. One tactic is using insecticides. These chemicals kill off larvae and adult insects. But with so many thousands of trees already infested, it’s difficult to identify and treat every tree.

Because ash borers don’t travel far from an infested tree, explains Knight, it’s people who introduce the insects to new areas. That can happen, for example, if people travel with infested wood for campfires. “We see new outbreaks pop up in campgrounds and along roadways where firewood logs are left,” says Knight. That sometimes leads authorities to establish a quarantine, making it illegal to transport wood out of infested regions and into new areas.

Scientists are trying many ways to fight ash borers, says Knight. One method is using insecticides. These chemicals kill off larvae and adult insects. But many thousands of trees are already infested, so it’s hard to find and treat every tree.

Ash borers don’t travel far from an infested tree. But people bring the insects to new areas, says Knight. For example, people may travel with infested wood for fires. “We see new outbreaks pop up in campgrounds and along roadways where firewood logs are left,” says Knight. That’s why authorities sometimes put a quarantine in place. This makes it illegal to move wood out of infested areas and into new ones.

A small number of ash trees in the U.S. are resistant to ash borer infestation, says Knight. Different species of ash trees grow in China, where most have also evolved a resistance to the insects. Scientists are studying these resistant trees to develop new ways to defend against ash borers in the U.S.

The U.S. Forest Service has also tried releasing wasps from China that prey on emerald ash borers into North American forests. But, unfortunately, none of the current methods have been powerful enough to stop the insects’ spread. That’s bad news for forests—and bat makers like Louisville Slugger.

A few ash trees in the U.S. are resistant to ash borer infestation, says Knight. Different species of ash trees grow in China. Most of them are also resistant to the insects. Scientists are studying these resistant trees. They hope to find new ways to defend against ash borers in the U.S.

The U.S. Forest Service has also tried releasing wasps from China into North American forests. These wasps eat emerald ash borers. Sadly, none of these methods has been powerful enough to stop the insects’ spread. That’s bad news for forests. It’s also bad news for bat makers like Louisville Slugger.

About 60 percent of Louisville Slugger bats are made of ash, says Boltz. These bats, which are less expensive than those made of other types of wood, are used by most youth-league players. While they would feel the effect of the loss of ash trees, says Boltz, “at the major league level, you won’t see as much of an impact.” That’s because about 80 percent of professional players currently use bats made from maple wood. But maple trees aren’t completely safe from insects either.

Like ash borers, Asian longhorned beetles snuck into the U.S. in wooden shipping crates during the 1990s. The beetles, named for their long antennae, burrow into maple trees to lay eggs. After a year, larvae mature into adults and chew a round tunnel to exit the tree. “It looks like someone drilled holes in the tree,” says Melody Keena. She’s an entomologist who studies insects at the U.S. Forest Service.

About 60 percent of Louisville Slugger bats are made of ash, says Boltz. These bats cost less than those made of other types of wood. They’re used by most youth-league players. Those leagues would feel the effect of the loss of ash trees. But, says Boltz, “at the major league level, you won’t see as much of an impact.” That’s because about 80 percent of professional players are using bats made from maple wood. But maple trees aren’t completely safe from insects either.

Asian longhorned beetles also snuck into the U.S. Like ash borers, they arrived in wooden shipping crates during the 1990s. The beetles are named for their long antennae. They tunnel into maple trees to lay eggs. After a year, larvae change into adults. Then they chew a round tunnel to leave the tree. “It looks like someone drilled holes in the tree,” says Melody Keena. She’s an entomologist who studies insects at the U.S. Forest Service.

Fortunately, longhorned beetles don’t do as much damage to maples as ash borers do to ash. But in areas like Worcester, Massachusetts, where there have been large longhorned beetle infestations, neighborhoods have been forced to remove their iconic maple trees.

Boltz is confident that the threat of these insect infestations won’t take his company out of the bat-making game. Louisville Slugger is already preparing to replace ash with maple and birch, he says. Because the future of ash trees is so uncertain, Boltz adds, “newer bat makers don’t even offer ash bats now.”

Luckily, longhorned beetles don’t hurt maple trees as much as ash borers hurt ash. But some areas have faced large longhorned beetle infestations. One is Worcester, Massachusetts. In places like that, neighborhoods have been forced to remove their maple trees.

These insect infestations are a threat, but Boltz is sure they won’t stop his company from making bats. Louisville Slugger is already preparing to replace ash with maple and birch, he says. Because the future of ash trees is so uncertain, Boltz adds, “newer bat makers don’t even offer ash bats now.”