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Lincoln Square, North Center, Irving Park

Mystery Of What Killed The Grass At Welles Park Is Solved — But Why Thousands Of Grubs Infested The Fields Is Still Unknown

The Park District also confirmed the grubs have infested sections of Winnemac Park, but the damage there isn’t on the same scale as what happened to Welles Park.

A vast number of beetle grub destroyed a swath of Welles Park, as seen on Oct. 22, 2021.
Colin Boyle/Block Club Chicago
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LINCOLN SQUARE — Experts knew the victim and the crime: Welles Park’s baseball fields were destroyed by an insect.

Now, they’ve identified the culprit: June beetle grubs.

But there’s still mystery around why the beetles’ larvae took over the park and damaged its grounds so extensively. Writhing masses of grubs have been greeting visitors to the park in Lincoln Square this month, creeping out neighbors and ruining a large portion of the park’s fields.

The bugs, about the size of a ring finger, chewed up about a third of the popular park’s 15 acres, laying waste to what was once an expanse of vibrant grass between five baseball diamonds on the the eastern half of the park. The infestation at the park at Montrose and Western avenues was first reported by WTTW’s Patty Wetli.

The grubs have also infested sections of Winnemac Park, but the damage there isn’t on the same scale, according to neighbors. 

Experts have confirmed the infestation is from the grubs of bugs known as May or June beetles, the Park District announced Wednesday.

“This is a common agricultural pest. The grubs eat the roots of plants and can quickly destroy large areas of crops — or, in our case, turf,” said Park District spokeswoman Michele Lemons. 

Welles Park will be treated for the infestation Wednesday, and Winnemac Park will be treated as soon as the weather permits the week of Nov. 1.

The district will use Dylox to eliminate the grubs, Lemons said. It’s deemed safe for people and animals, but neighbors should avoid the treated areas for about two hours after crews are done.

Credit: Colin Boyle/Block Club Chicago
A vast number of beetle grub destroyed a swath of Welles Park, as seen on Oct. 23, 2021.

By next week, park staff will begin fertilizing and seeding the fields using a “dormant seeding” technique, which means the grass seeds will likely not germinate until the soil is warm enough in the spring, Lemons said. Another round of seeding will happen in the spring as soon as weather allows.

The fields will remain closed until the grass has adequate root growth to withstand typical use from sports.

“Depending on weather conditions this fall, spring, the fields will reopen for use between late May and late June. We will do our best to get the fields open for play as early as possible,” Lemons said.

Beetle grubs are present in smaller numbers in many parks, but the large scale of the turf damage caused by the grubs at Welles and Winnemac is still being investigated. After heavy rains, thousands of beetle grubs emerged from under Welles Park in Lincoln Square.

“We have not determined the cause for the grub population surge, but experts have suggested that the weather patterns may have contributed to the large numbers,” Lemons said.

Christopher Dietrich, the state’s official entomologist, said this summer’s weather was pretty dry compared to other years, so the beetles would have looked for an extra moist patch of grass to lay their eggs.

If the ball fields were overwatered to compensate for the drought, that would make that grassy area more lush and, thus, more attractive to female beetles looking to lay eggs, Dietrich said. This is why he recommends people don’t overwater lawns during the summer.

combination of warm weather, rainy skies and excess trash earlier this summer led to what some critter specialists are calling an “explosion of pests” like flies

“We have all these weird weather events, with these fluctuations between drought and wet. These are the kinds of things that can cause these types of outbreaks in an insect population,” Dietrich said.

Experts the Park District spoke to also pointed to unusual weather patterns to help explain the infestation. Lemons confirmed park staff water the baseball field grass, but she said they only do so “as needed when new grass is being established.”

In a letter to parents Tuesday, the Welles Park Parents Association — which serves 1,600 kids and teens ages 5-19 — said games at Winnemac and Welles parks for the 2022 season would be impacted by the timeline for the treatments. The group also uses diamonds at Legion Park, Green Briar Park, Mather Park, Hollywood Park and River Park to host softball and baseball games.

“We are in active discussions with the Chicago Park District and also private facilities where we can hold our games and practices,” Ross Kerr, the association’s president, previously told Block Club. “[There’s] some work ahead of us to make it come back together, but we are committed to doing all we can.”

RELATED: 

Welles Park Grub Infestation Will Shut Down Youth Sports Until At Least Next Summer, Parent Group Says

Nightmare On Montrose: Grub Infestation Leaves Welles Park Stinking Of Rot And One-Third Destroyed

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