The life cycle of the wasps is such that the nests become very large in late summer and the nest becomes populated with adult wasps that will readily defend the nest. Fortunately the wasps rarely sting when passing near the nest, but accidently stepping into or on a nest in late summer is a hazard.
I managed to avoid stepping into any nests last summer and thus far have a avoided doing so this late summer. Last week a client helpfully alerted me to a nest along a survey path cut through the brush prior to my field venture. I noted the small fast flying wasps near the nest shown above before spotting the entrance.
My last encounter with stepping into a nest was on a very steep slope. The usual fast escape via running was impeded by the slope conditions which meant I had to crawl up the steep slope as fast as I could and likely further disturbed the nest as I began my escape. Once I reached the top of the slope, I was able to run, but continued to be stung. The next step was to shed my shirt and pants as fast as I could. Wasps release odors when they sting which stimulates additional stings and additional wasps to attack. My car was not far away and I had extra clothes (a typical habit as I often get wet doing field work). Even a half hour after my encounter there were still wasps stinging my dropped shirt.