Missouri’s ash trees face destruction at the hands of a tiny insect that has wreaked havoc in the St. Louis area and infested much of Southeast Missouri.

Colonies of the emerald ash borer have been spotted in 23 Missouri counties, including 16 in Southeast Missouri, said community forester Jennifer Behnken of the Missouri Department of Conservation.

The destructive insect has not been detected by the Conservation Department in Cape Girardeau and Scott counties, but Behnken suggested it will happen.

“It really is only a matter of time until it creeps up,” she said.

Twelve of the 16 infested counties in Southeast Missouri were added to the growing list this year, she said.

The Asian bugs are killing ash trees, causing millions of dollars in damage to forest products and ruining the forest and urban landscape, she said.

The city of St. Louis has about 15,000 ash trees planted along its city streets and in its parks. This month, the city started chopping down the trees at risk of attack from the dark metallic-green, half-inch-long insect.

Behnken said ash borer larvae feed on the inner bark of ash trees, eventually killing them.

“When they die, they degrade quickly,” she said.

Missouri’s first confirmed sightings of the insect occurred in 2008 and spread to St. Louis last year.

The ash borer has been found in 26 states, from the East Coast to the Midwest.

A special insecticide can be injected into ash trees, but only if the trees have not been infected, she said.

“It is a pre-treatment measure,” Behnken said.

Such treatments, however, are expensive, costing $100 to $300 per tree. The treatment lasts two years at the most, meaning the insecticide would have to be reapplied again and again over the life of the tree, she said.

Ash had been a popular urban tree, particularly in the nation’s large cities, because it is fast-growing, tolerates a variety of environments and has a nice shape, Behnken said.

Unlike St. Louis, Cape Girardeau and Jackson have not experienced an infestation.

Cape Girardeau parks and recreation director Julia Thompson said the city has a diversity of tree species, making it less vulnerable to such infestations.

Cape Girardeau has not planted ash trees throughout its public spaces as St. Louis did, she said.

Thompson said the city has removed ash trees “if they are ready to come down.”

When Cape Girardeau removes an ash or any other tree, it seeks to plant new trees of species that will thrive in this area.

“We always try to replace them,” she said.

The city has a tree board that advises the local government on care, preservation, planting and removal of trees in parks, along streets and in other public areas. The city lists 48 tree species that can be planted on public land. Ash is not one of them.

“Cape has always really cared a lot about the trees and tried to protect them,” Thompson said.

Shane Anderson, Jackson’s director of parks and recreation, said ash trees account for perhaps 5 percent of trees in the city park.

“We have not seen any emerald ash borer in our city trees,” he said.

Behnken said the Conservation Department encourages local governments to work with a forester to manage ash-tree populations.

Many infestations start when people move infested ash firewood to new locations, she said.

A statewide quarantine, enacted by the U.S. and Missouri departments of agriculture in 2013, prohibits the movement of any part of an ash tree to other states that have not seen the infestation.

The bugs first were detected some years ago in Michigan. Behnken said it is believed they arrived accidentally in shipping and packing materials.

Behnken said she would advise residents to “vaccinate” their ash trees or cut them down if a confirmed infestation is found with 15 miles of their location. Otherwise, she said, they risk losing their trees to the deadly bug.

mbliss@semissourian.com

(573) 388-3641

Pertinent address:

2302 County Park Drive, Cape Girardeau, Mo.