What destructive creatures thrive in the summer after warmer winters?

SIOUX FALLS, SD (KELO) – It’s summer and among us small, destructive creatures are thriving in South Dakota’s mild winter temperatures.

“Warmer winters provide better habitat for Emerald Ash Borers (EAB) to reproduce, move, lay eggs and find ample food,” says Chris Ernster, co-owner of Prairiescapes Tree Service and Landscaping.

The last two winters have missed several days or nights with temperatures of minus 25 and minus 30 degrees. Cold temperatures can kill most EAB larvae.

EAB beetles have been spreading across South Dakota and numerous other states for years, killing about 100 million ash trees.

“Forty percent of the trees, or about 80,000 trees, in the Sioux Falls area are Emerald Ash,” Ernster says. “That provides a lot of food for the borer beetles.”

According to the city of Sioux Falls, the one-inch-long, green beetles emerge from infested trees and fly to other nearby ash trees to lay their eggs on the bark. The larvae waste no time growing and hatch into flat, white worms within a week or two. The worms immediately go to work and dig into the inner bark of the tree to feed.

The worms create tunnels that cut off the movement of food from the leaves to the roots. This weakens the trunk and limbs. In high winds, it is common for an affected tree to lose limbs and branches.

Once the tree is affected, it can survive for one to seven years, but it is normal for it to die after five years.

Since the inception of the EAB program in 2018, Sioux Falls has had a tree removal/treatment plan in place. If the tree is on the boulevard, the city will cut the tree down at no cost to the landowner. Removal of the stump is not included.

EAB treatment, courtesy of Prairiescapes Tree Service and Landscaping

To save the tree, it must be treated by a commercial applicator every two years until the outbreak is over. Depending on the size of the tree, costs can vary from €150 to €400 per treatment. It is recommended to treat the tree biannually. After the tree has been treated, an EAB metal plate is placed in the tree as treatment documentation.

Because there are more larvae present this year, Ernster recommends treating the trees earlier – in June instead of July – to limit the damage caused by the EAB.

“There are areas in the Sioux Falls area that are heavily contaminated, such as along the bottom of the Big Sioux River,” he said. “If you travel along the I-229 corridor and continue north of 10th Street to I-90, these areas have been heavily impacted by EAB. The ash trees in the 63rd & Cliff area are also severely degraded and damaged.”

“We have had a lot of rain this year and most of the trees look vibrant and healthy. But when an ash tree is infested, you can physically see the tops dying and the tree not leafing out. That is a clear sign,” Ernster said. “Another sign is that as the tree tries to survive, it sends out shoots toward the bottom of the base.”

Heather, treated Emerald Ash tree

Ernster said the city is doing a good job removing infected ash trees from city-owned areas. It is an expensive and labor-intensive process, but treating and saving the trees has many benefits.

Trees are good for the environment and ecosystem because they provide shade, emit oxygen so we can breathe and absorb CO2 from the atmosphere. Trees also provide shelter for many species of birds and other animals. Aesthetically, trees benefit homeowners’ properties, communities and the earth as a whole.

According to the National Forest Foundation, a single tree can remove and absorb half a ton of CO2 over a 100-year lifespan.

Do Emerald Ash Trees Need to Be Treated Indefinitely?

“We are currently looking at a ten-year period (of EAB treatment). We will never eradicate the borer, but we expect that treatments can be reduced to every three years in the near future,” Ernster said.