I've only had one experience with ground nested bees. I was with a small group miles from anywhere heading for the final climb and cache of the day...heat index over 105...first time EVER wearing shorts caching. I stepped straight into the nest and was stung by every bee in the nest, or so it seemed. Fortunately I have no reaction to bee stings (or poison ivy either), so other than an extraordinary amount of welts I excaped OK.