UPPER PENINSULA, Mich. (WJMN) – Little caterpillars with a big appetite. The Department of Natural Resources (DNR) thinks these hungry herbivores could be the reason jack pine trees in the Upper Peninsula and Northern Lower Peninsula have brown branches.

The possible offender, budworm caterpillars. The DNR shared that they eat needles on jack pine and red pine trees. Adult moths, are reddish-brown with white markings. Needles that have been chewed on or damaged by the caterpillars will turn reddish brown in July. Once wind and rain take away the dead needles, the trees then look bare, even a little gray. The caterpillars also lay their eggs on jack pine needles.

According to the DNR, the budworm is native to Michigan. Outbreaks happen every six to 12 years, with the population dying off after two to four years.

“What we’re seeing right now is an outbreak that started in 2022 with infestations in the central and eastern Lower Peninsula and some small pockets in the U.P.,” said Simeon Wright, forest health specialist with the Michigan Department of Natural Resources. “The last large outbreak was in 2015.”

About 28,000 acres were defoliated during 2022, compared to 118,000 acres during the last large outbreak in 2015. 

The DNR said severe infestations will kill trees or cause the tops to die back, which can create fuel for wildfires.