Workers/defenders will aggressively defend their nest by stinging anything causing a disturbance, this is not generally bad behaviour by wasps but a natural part of their instincts. They can sting repeatedly. The venom of a wasp sting contains a pheromone which acts as an alarm causing other wasps to become more aggressive when a wasp has stung something or been killed. So it is a bad idea to swat a wasp near its nest.
Wasps are not normally aggressive to humans, but as a result of overcrowding and temperature in the nest, they can become so.
The internal temperature of a wasp’s nest is 5 – 10ºC above the outside temperature. When outside temperatures reach 25 ‘s 30ºC the temperature inside a wasp nest can be very high indeed.
In late Summer/early Autumn when the workers’s job is done, they gorge themselves on the food they collect, especially sweet foodstuffs like fruit, and often gets drunk when the fruit is fermenting.
Consequently, on a hot day, when the nest has more than a thousand inhabitants, and a foraging wasp has had a little too much fruit and nectar, he will be bad tempered, hot and bothered, slightly the worse for wear, and may well react badly when being prevented from tasting your cola, beer, or wine, or from sampling your barbecue or picnic.
In the absence of effective wasp Asbos, Waspinator is the only thing which will make them go away, if only to next door’s.