Bald-faced Hornet

While working on the Routt National Forest this week, I saw more bald-faced hornets (Dolichovespula maculata) than ever before.  Has there been a population boom?  Like most stinging insects, these won't bother you as long as you leave them alone.  Unfortunately, it is difficult to leave them alone.  When you're walking cross-country through the forest, especially where the brush is thick or there are downed logs, it is not inconceivable that you will brush, crush, or step-on one of their nests.  On Wednesday, I stepped over a log and onto a large rolled piece of bark that was housing a colony.  Fortunately, there was about 100 meter clear area in front of me, so I sprinted away (Usain Bolt wouldn't have believed his eyes).  I wasn't stung, but it scared me.  The two nests pictured (above and below) were near each other in a little clump of aspen.  I noticed them without mishap, but they would have been easy to brush or bump as I walked between the trees.