EHD in Idaho: What Hunters Need to Know

As hunters, we care deeply about the health of Idaho’s deer and elk populations. One disease that occasionally makes headlines is epizootic hemorrhagic disease, or EHD. While not new to Idaho - and usually limited in scope - it’s important to understand what EHD is, how it spreads, and what it means for hunting seasons.

EHD is a viral disease spread by tiny biting midges, often called “no-see-ums.” When these insects bite deer, they can transmit the virus, sometimes causing fatal illness. The disease can affect elk and mule deer, but it’s usually only fatal to whitetail deer. In bad years, EHD can cause population-level impacts in localized areas where whitetails are most vulnerable.

Most outbreaks in Idaho are small. A few deer may die in a given area, but overall populations remain healthy. However, when conditions line up just right, more significant outbreaks can occur. During drought years, limited water forces deer to congregate around the same sources, increasing exposure to biting midges that thrive in stagnant water. Under these conditions, EHD can spread rapidly through a localized herd.

Fortunately, outbreaks don’t last long. Because the virus depends on midges, a hard frost or a stretch of cool, wet weather quickly knocks back the insect population. That’s why EHD outbreaks are usually short-lived and confined to specific regions.

While EHD can be alarming, it does not wipe out deer populations statewide. Whitetail hunting opportunities remain strong across Idaho, and even if one area is affected, nearby regions often see little to no impact.

This year, both the Panhandle and Clearwater regions have confirmed reports of EHD and while reports of dead deer have recently increased, we’re still a long way from the numbers reported in the 2021 outbreak. With cool and wetter weather in the forecast, we’re hopefully nearing the end of this year's cycle and we will escape without a major die-off. Our whitetail deer have weathered EHD outbreaks for generations. While it can cause significant local losses, the disease usually runs its course quickly and populations bounce back. As hunters, keeping an eye out for signs of EHD and sharing what we see with wildlife managers ensures we’re doing our part to support healthy herds and sustainable hunting for the future.

EHD is part of the natural cycle for Idaho’s deer populations. While hunters can’t prevent outbreaks, we can stay alert, report what we see to wildlife managers, and do our part to support healthy herds. By staying engaged and informed, we help ensure sustainable hunting opportunities for years to come.

If you come across a dead or sick deer, please report it to IDFG on their wildlife health reporting page here, https://idfg.idaho.gov/species/whl/report