by
Wednesday, July 31, 2013
There are a couple places in Virginia where the deer kill last season was down 30 percent, enough to impact the success of hunters. Virginia Department of Game and Fisheries' officials say much of the decline can be blamed on Epizootic Hemorrhage Disease, succinctly known as EHD or just HD.
HD occurs late summer and early fall and is carried by biting insects commonly known as midges, sand gnats/flies and no-see-ums of the genus Colicoides. They are so small that they are difficult to see, but they feel like burning cinders when they contact your skin. They are an irritant to people but can be deadly to deer.
Annual outbreaks of HD are common in Virginia and many other states. Often they are mild in intensity, but sometimes they are bad enough to take a bite out of the deer herd. The two high-impact areas in Virginia last year were the Caroline-King George County area and the Patrick-Henry County area including some spillover along the Franklin County line.
I have been wondering if the wet summer of 2013 might be the beginning of a major HD year. I known there have been many places where I've experienced swarms of gnats and stinging flies that gnaw at my ankles and dive-bomb my bald head. I figure these pests have benefited from a wet season that enhanced their breeding opportunities, so why not the same for midges, the vector of HD?
I ran this concern by Matt Knox, deer project leader for the DGIF.
"I think we may have had our first report of HD from Bedford County last week at Smith Mountain Lake," he said. "This is early."
But according to a weather profile put together by biologists including Knox, midges benefit from a mild winter, a hot summer and drought conditions during early summer. Major HD outbreaks occurred in 1999, 2002 and 2005. In 2005, 5.2 percent of the deer examined were impacted by HD, the highest ever recorded. Last year, that number was 2 percent.
"We had a fairly normal winter this year and obviously we did not have a June drought," said Knox.
In reality, drought appears to benefit midges and the spread of HD more so than an abundance of rain. But this summer rainfall has set records, so who knows?
"I have no idea what to expect," said Knox.
Drought appears to create favorable conditions for HD by enhancing the environment for midges, which breed along the edge of water, and by drawing deer to the very places midges are most abundant. The spread of HD is from insect to deer; not deer to deer.
Drought appears to create favorable conditions for HD by enhancing the environment for midges, which breed along the edge of water, and by drawing deer to the very places midges are most abundant. The spread of HD is from insect to deer; not deer to deer.
There is no way to prevent or control HD. It is seasonal, peaking somewhere between August and October, and ending with the first heavy frosts of autumn, which take care of the midges.
In some states, kills of up to 50 percent of the deer have been reported. The herd bounces back, but it takes time and hunters feel the impact and often express alarm.
For a time, HD was just a problem in Virginia east of the Blue Ridge Mountains, but in 2007 it showed up in the west in a big way, and the same thing occurred last year.
Hunters who participate in Virginia's deer management assistance plan are major contributors of information on the severity of HD. They help monitor deer, checking for signs of HD on their property and in their kills. Those signs include deer with swollen heads, necks, tongues or eyelids, along with lameness and emaciation. In some instances, death appears in a few days.
Humans cannot contract HD from fly bites or from eating venison, so evidence or threat of the disease should not disrupt scouting and hunting. Most hunters probably aren't even aware of the problem even in impacted areas; they just know they aren't seeing as many deer as normal.
