Wasps get more aggressive by July. There's a reason
A colony's behavior changes over the season — and changes significantly by late summer.
The sense that wasps grow pushier and meaner toward the end of summer is not subjective. Their behavior really does change, and the cause lies in the colony's life cycle.
In spring and early summer the colony is growing, and the workers are busy feeding larvae. Larval food is protein — insects, carrion, meat. In this period wasps are useful as predators and take almost no interest in people.
By July and August the picture shifts. There are fewer larvae, the need for protein falls, and the adults want carbohydrates — sweets. That is when wasps show up on tables, at trash bins, at fruit stands, and in kitchens. At the same time the colony's overall numbers grow, and by season's end competition over dwindling resources is added on. Hence the aggression.
What follows from this. First, a nest is better found and removed in early summer, when it is small, than in August, when it holds hundreds. Second, in the latter half of summer the main measure is removing sources of sweets: keep sugary drinks covered, do not leave fruit and preserves in the open, keep the trash containers in order.
And on safety: a wasp, unlike a bee, stings repeatedly, and in doing so releases an alarm pheromone that draws others from the nest. Swatting and flailing is the worst strategy, and next to the nest it is outright dangerous. If the nest is large, sits in a wall, in the attic, or somewhere hard to reach — and especially if anyone in the household is allergic to stings — this is work to hand to professionals.
