An infected moose | Michigan Technological University
Michigan's Upper Peninsula moose population has faced tough times for years, remaining largely stagnant despite suitable habitat and conservation efforts. One major culprit of the decline is believed to be the presence of winter ticks, a relentless parasite that infests moose in massive numbers, causing severe health issues and contributing to poor calf survival. With more warm-weather winters than usual, these ticks are able to thrive, as extreme cold no longer kills them off effectively.
As state biologists, hunters and wildlife advocates scratch their heads about how exactly we ought to deal with such an unstoppable rebel force, some innovative student-led research at Michigan Technological University is exploring a natural, plant-based solution. Native to the area and common in moose habitat, researchers are turning to the essential oil found in balsam fir trees as a possible solution. Building on prior studies showing the effectiveness of balsam fir oil against other tick species, this new initiative offers a glimmer of hope for a low-impact way to combat this growing threat.
Winter ticks are single-host parasites with a one-year life cycle, fueled largely in part by engorged females that drop off moose in spring and lay thousands of eggs in leaf litter. Larvae then hatch and climb vegetation in fall to "quest" for hosts, often latching onto moose in huge clusters, and feed through larval, nymph, and adult stages over winter before dropping off in spring.
A heavily infested moose can carry a whopping 20,000 to 75,000+ ticks, leading to severe blood loss, anemia, and malnutrition. These infestations also result in intense itching that prompts excessive grooming and hair loss and thus reducing the animal’s insulation against cold, increasing vulnerability to hypothermia and death.
An infested moose | Lindsey Welch, National Park Service
Calves suffer the most, with high tick loads linked to poor survival rates. In Michigan's U.P., recent DNR surveys (including 2025 aerial and drone data) have shown unexpected population drops and visible signs of tick-related hair loss. This compounds other pressures like habitat changes and limited food sources, such as overbrowsed balsam fir—the moose's preferred winter browse.
Balsam fir, abundant in northern forests, has shown tick-killing potential in earlier research, including a 2022 study found that balsam fir needles and their essential oil (rich in compounds like β-pinene) effectively killed overwintering black-legged ticks at cold temperatures, with near-100% mortality in days—more effective in winter conditions than at warmer temps.
Grace Moeggenborg, a 2025 MTU graduate in applied ecology and environmental science (from St. Johns, Michigan), hypothesized this could extend to winter ticks, especially vulnerable larvae. Mentored by MTU faculty, Moeggenborg secured funding from a Garden Club of America scholarship to launch the project.
Fieldwork began last summer and saw Moeggenborg conduct a number of tick-drag surveys in moose-frequented U.P. forests, dragging a white cloth through vegetation to collect questing larvae (often jumping onto her or the cloth, which she removed with tweezers and vialed for lab transport).
In the lab, she then exposed collected larvae to balsam fir essential oil in controlled vials.
Initial results were mixed with the first round of testing showing no statistically significant mortality from the oil. Moeggenborg notes potential confounding factors like humidity, temperature, or lighting may have influenced outcomes. However, she remains optimistic.
Grace Moeggenborg, with the guidance of @mtuforestryenv faculty Tara Bal and Sarah Hoy, is researching a way to reduce winter tick populations using essential oil from balsam fir trees native to the region.
“I think long range, it is feasible to test the ticks in more controlled conditions and find a more concrete answer about the balsam fir essential oil and its efficacy,” she said. “My hypothesis is that it does work, especially in the larval stage, where they’re young, they’re small, they don’t have a lot of defenses up yet.”
When it comes to implementation, delivering the oil in the wild poses challenges as moose don't naturally rub on trees like some animals. To help them along, researchers are mulling over a number of proposed ideas such as cow brushes or other self-application devices in forests that could be loaded with diluted oil to help spread the solution as animals like moose pass by.
Enclosed bait stations could also be used to mist or spray moose as they feed or pass through.
An alternative approach would come from above. Researchers believe that an aerial or targeted application, such as low-concentration spraying or crop-dusting over leaf litter in the fall would hit eggs and larvae before they begin to quest, while carefully avoiding broad environmental harm.
Moeggenborg has applied to continue as an MTU master's student, planning refined lab tests under stricter controls for clearer efficacy data on larvae and other stages.
This research aligns with ongoing efforts by the Michigan DNR, Keweenaw Bay Indian Community, Northern Michigan University, and others—using GPS collars, drones, and surveys to understand moose declines. If balsam fir oil proves effective, it could offer a biodegradable, native-plant-based intervention that leverages local resources without relying on synthetic pesticides that might affect beneficial insects.
