Before any kegs are tapped, we have work to do. These virmen are no different than the virmen on the Wandering Isle... a nuisance that breeds as fast as the rabbits they resemble.
Sure, we could kill every last virmen we find, but what's the point in needless bloodshed? Let's just take out their alphas, and they'll slow down with their... reproduction.
The three can be found within the Sunsoaked Meadow immediately north of Mudmug's. The first two can be found at the trees (looking behind Mudmug's); the third can be found due west of them in a straight line, sitting atop a small rise.