Rob in VT

EHD also seems to target mature bucks more than any other age deer. Very strange indeed. One time in Illinois Champlain Islander and myself found a half dozen or so dead deer in a creek on the farm we were hunting.

MudderChuck

Just supposition but if/when you find a large kill you might want to check out local Sheep herds.

We had no Blue tongue at all as far back as anybody could remember until a Sheep herder brought a flock of Sheep through our lease. There may or may not be an association, but I've never been a big believer in happenstance.

Is it possible domestic flocks or Cattle help transmit the disease to unaffected areas and/or more susceptible hosts like Whitetail?

Only two things I can think off to slow down the disease, is culling infected animals and spraying fly brood areas. The stock answer here is to seriously thin out the Deer herds for most kinds of disease and try to slow down the transmission cycle.

Many variations of EHD my thinking is it may be like the flu, constantly evolving.

Maybe one reason we have so few cases here is they spray for Mosquitoes intensively here. I imagine the same spray works on Midges. Maybe the Roe and Red Deer aren't as susceptible? Maybe it is because we rarely let the Deer herds over populate which slows down the Deer to fly to Deer cycle.?

MudderChuck

Some parasites share hormones with the host and the hosts hormones are necessary for reproduction. Is it possible biting flies and blood suckers may have similarly evolved?

rockport

I'd say it has something to do with the behavior and/or requirements of mature bucks but it is definitely harder on mature bucks.

I'm sure big mature bucks require more water which leads to more exposure.

In my area EHD is very clearly related to drought.

MudderChuck

Maybe the water drying up forces the larvae to pupate and turn into mature flies? They are kind of forced to mature all at once or nearly so and the fly density spikes?

They must have some sort of mechanism to survive winter, either the eggs, larvae or pupae must go dormant for long periods. I've seen the same with Maggots, if they run out of food they will pupate early (under size).

rockport

Maybe, Ive always been under the impression that drought just forces deer to use the stagnant water holes where these gnats are concentrated but there could be more to it than that.

The gnats like water, the deer need water, and there is very little water available = lots of interaction between deer and the gnats. Bigger deer need more water = even more exposure.

tatonka

From what I understand, EHD causes the deer to bleed internally, which is why they are usually found near water when they die... The loss of blood causes extreme thirst. In regards to it hitting bucks the hardest, I've also read that antlers in velvet being full of blood are like a huge magnet for the gnats (midges). Bucks tend to lay pretty low when their antlers are in velvet and tend to stay in the low, damp areas were the midges are...they don't move around as much as the does and fawns.