Yellow Jackets becoming more aggressive this time of year? It’s not your imagination

Anyone outside this time of year, especially if you are eating or drinking something, has noticed the increase in numbers of wasps that seem to be flying around them.

During the summer, a yellow-jacket colony is focused heavily on raising larvae. The workers spend much of their time hunting insects and bringing food back to the nest. The larvae produce sugary substances that feed the adult workers.

By late summer, however, the colony’s priorities change:

The queen slows down egg production. Fewer young are being raised, so the workers aren’t spending as much time caring for larvae.
The colony loses its major source of sugar. With fewer larvae producing sugary food, the adult workers become much more interested in finding their own carbohydrates. This is why they suddenly show up around people. Foods such as meat, sugary drinks, garbage and anything sugary become extremely attractive to them.

As the colony gets older and eventually begins to break down, yellow jackets can become more aggressive about protecting their remaining food and nest.
Warm fall days make them especially noticeable. They’re still active when temperatures are mild, but they’re essentially running out of time before cold weather ends the colony.

One important distinction: the yellow jackets you’re seeing aren’t necessarily trying to attack you. They’re often simply investigating you because you’ve got something that smells interesting. However, because they’re much more food-driven and defensive in the fall, they’re more likely to fly around your face, land on you, or sting if they’re swatted or trapped against your clothing.

And here’s the really interesting part: the workers you see in September and October generally won’t survive the winter. The old colony dies off, while newly produced queens leave to find sheltered places to overwinter and start new colonies the following spring.

So if you’ve noticed, “Where the heck did all these yellow jackets come from?!” — you’re not imagining it. Fall is basically yellow-jacket season.