Behavior
The common yellowjacket will nest in abandoned tree trunks, and is more often found away from urban areas and in higher elevations. Like other wasps and hornets, it has a beneficial function, because it kills other insect pests, then chews up those pests to feed to larvae in the nest. It will defend its nest when threatened, although perhaps not with the aggressiveness of other species of wasp.
Treatment
If you can, avoid yellowjackets, and avoid disturbing their nests. The common yellowjacket will feed on flies, mosquitoes, caterpillars and other pests, so they can be beneficial. There are aerosolized pesticides you can buy, but using them, especially without knowing the dangers, can be quite risky. Measures you can take: Improve sanitation by keeping food sealed in containers, and by locating garbage receptacles away from where human activity; keep in mind that these insects need water, also. If your yellowjacket situation gets out of hand, call your Clark Pest Control technician, who will handle the wasp infestation for you.