New queens spend the winter in logs, piles of leaves and other sheltered areas, emerging in spring to look for places to build their nests. (Yellowjackets rarely reuse old ones.) Eastern yellowjackets typically choose underground sites in covered, out-of-the-way areas that are normally easy to avoid, unless they’re in landscaping, compost piles or frequently mowed areas. German yellowjackets, on the other hand, prefer natural cavities and spaces in man-made structures, making them more likely to be in walls, doorways or sheds.
Inside the nest the queen builds stacked rows of hexagonal paper cells using pulp she makes from her saliva and chewed-up bits of wood. In each cell she lays a single egg. When the first few hatch, she feeds the developing larvae protein-rich caterpillars, earwigs, spiders, worms and carrion (decaying animals). After the first 20 or so workers take flight, her only job will be to remain in the nest and lay eggs until she dies. Her ever-growing family of winged workers, now on a diet of sugars from fruits, flowers and unguarded soda cans, will be responsible for building new cells and feeding the larvae inside.
Each sealed cell of a yellowjacket nest contains a single egg. After the eggs hatch, the growing wasps remain in their cells for about 20 days before emerging as winged adults. Image by Thomas Bresson/CC BY 2.0
Most yellowjackets go unnoticed by humans in spring and summer and even provide unintended benefits. One nest can remove nearly 2 pounds of insects in a single summer and protect many gardens and flowerbeds from insatiable caterpillars.
German yellowjackets can be an exception. These highly aggressive wasps fiercely defend their nests, harassing and chasing intruders for long distances, and are likely the ones interrupting picnics or buzzing around trash cans. They’re also the ones most likely to sting (and a yellowjacket can do so multiple times).
Once fall arrives, though, all types of yellowjackets become more conspicuous. Colonies are their largest, and because developing drones and fertile females inside each nest need far more protein than earlier broods, workers are their busiest.
Yellowjackets have been going through this cycle for thousands of years, so the best way to deal with them is to be prepared. Cover sugary drinks and garbage cans, and keep an eye on anything you’ve pulled off the grill. (To a yellowjacket looking for protein to feed the colony’s larvae, a piece of barbeque chicken is just as good as carrion.) And if you see yellowjackets around, don’t assume they’re out to get you. Give them space and they will most likely do the same for you.