Information adapted from our Bug Blog:
Vespula germanica or the German yellowjacket are the dominant species of yellowjacket that we encounter. Other yellowjacket species are also present in our area, notably the bald-faced hornet (Dolichovespula maculata). This species is very obvious thanks to their unique white and black coloration.
Yellowjacket nests can take several forms, depending on the species; some construct nests in the open, the combs covered by a paper-mache like outer shell. Others build nests in wall voids, old rodent burrows, hollowed-out trees, or within the shelter of a dense bush. Regardless of where they build their nests, all yellowjacket workers (the ones flying around your picnic like it was meant for them, and them alone) can sting, and unlike a bee, they can sting multiple times.
Here in Ohio, our winters dictate that the nest is a one-season affair. The number of workers in a late season nest can approach 4 to 5 thousand individuals, though most nests will only be in the 1 to 3 thousand range. As the cold sets in, the workers die off and the new queens will leave the nest, finding a sheltered place (your attic, for instance) where they will overwinter and wait for spring, when they will locate a new nesting site and begin the process of forming a new colony. The old nest may remain intact through the winter but will not be re-used.
One word of caution, we have encountered several instances of homeowners using kerosene poured into a ground nest and lit aflame in order to eliminate the nest. This can be extremely dangerous and environmentally harmful, as well as being illegal. Here at Bainbridge/SPS Pest Control we have the capability to treat existing nests safely and efficiently. Our Power Spray service option can also provide a measure of long-term deterrence to the building of new nests. We also will be happy to install and service, or sell directly to you, yellowjacket traps, which have proven very effective for temporary control.