A frend of mine and I were scrambling up the Talus slope below Eagle cliff and stopped on a large flat rock about half way up. We were talking qiuetly, and eating when all hell broke loose. I was looking at my friend when the first wasp nailed him in the back of the head. I got up and started running and jumping up and over boulders as large as houses, while getting stung about a dozen times (including in the ear and on my nipple). The wasps followed me for over 100 feet. The odd thing was we never saw a nest, we were quiet, we were still, and got stung before any "swatting" began. I was wondering if anyone else had a similar experience or or an opinion as to what triggered them.