A bug to watch for (and if you spot it, call someone fast)

The emerald ash borer is coming. Slowly, yes, but when it gets here, all of our city’s ash trees are in grave danger. It could take as many as 60 years before the Asia-originated beetle, smaller than a dime in size, arrives in Minnesota. Yet tree experts around the state already are taking steps to minimize the damage the bug will ultimately cause. It’s that serious.

The bug

Ralph Sievert, director of the Minneapolis Park & Recreation Board’s forestry division, has a favorite saying when it comes to the bug:

“You won’t even remember Dutch elm [disease] when the ash borer hits,” he says.

Those are powerful words, considering that Dutch elm disease killed millions of trees in Minnesota alone. They’re also powerful because the emerald ash borer is unassumingly small; dimes are bigger.

The exotic beetle showed up in southeastern Michigan in 2002, probably carried there by wood-packing material from its native Asia. The adults don’t cause much damage. The larvae, on the other hand, eat the trees’ inner bark, disrupting their ability to transport water and nutrients.

They’re not picky about their ash: Sievert said ash trees of all types, sizes and ages are susceptible.

They have wreaked havoc in Michigan, Ohio, Indiana, Illinois, Maryland and Ontario. They’re not in Minnesota yet, but the state’s experts anticipate their arrival here within the century.

The battle

There is no known way to eradicate the emerald ash borer. The only action to be taken at this point is preparing as well as possible.

If the beetle migrates naturally, it could take 60 years for it to show up in Minneapolis. In that case, the Park Board would be well set. Treating ash trees is near the bottom of its priority list.

Otherwise, “it just adds to more trees we have to deal with later on,” Sievert said.

The Park Board hasn’t planted any ash since 2005, and it barely prunes them anymore. The board also has lowered the threshold for when it’s appropriate to remove ash.

By letting the species naturally die out, there would be little left for the emerald ash borer to damage when it finally arrives. But that strategy’s success hinges on the beetle taking a half-century to get here.

Many find that highly unlikely.

Some think it’s already here.

Part of the problem is that the emerald ash borer is very difficult to detect. It could infect a tree and take years before it’s spotted. By that time, the fate of the ash it’s inhibiting already has been sealed.

That’s why, Sievert said, a lot of efforts are being put into trying to slow the beetle’s arrival in Minnesota. The forestry division has partnered with the Minnesota Department of Agriculture in planting trap trees, cutting of the bark off select trees to expose its wood. When the tree dies, it releases pheromones that attract the ash borer. The agriculture department then performs an autopsy to test for the bug’s presence.

In the meantime, Minnesota is hoping nobody brings in firewood from emerald ash borer-afflicted states. But, “there’s bound to be someone,” Sievert said.

Where’s our ash?

While ash trees are much more prominent in Northern Minnesota, there are plenty of them in the metro area.

Sievert said Minneapolis is home to about 210,000 ash trees spread fairly evenly around the city. “They’re kind of an ideal tree for an urban area,” he said.

Ironically, many ash were planted in the 1970s as Dutch elm disease destroyed thousands of elm trees.

What you can do

First off, don’t be the one who carries over firewood from one of the afflicted states. But you also can be helpful by keeping your eyes on the trees.

The Department of Agriculture has set up a hotline for people to call in emerald ash borer sightings. Before doing so, however, they have a series of steps they’d like callers to take before dialing the number.

For example, the department would like for callers to first make sure they’re actually looking at an ash tree. Next, they want them to make sure they’re seeing basic emerald ash borer symptoms, such as canopy dieback, larger-than-normal leaves and sprouts growing from the tree’s roots and trunk. Other symptoms can include bark splitting and increased woodpecker activity.

Also, even if the bug looks like an emerald ash borer, it could a look-alike, such as a six-spotted tiger beetle or a caterpillar hunter.

If you feel confident you’ve spotted the emerald ash borer, call the “Arrest the Pest” hotline at 651-201-6684, or e-mail [email protected].

Agriculture department spokesman Mike Schommer said there were about 120 reports of ultimately erroneous emerald ash borer sightings in Minnesota in 2007. So far in 2008, the department has received about 10–15 reports.