There are many thousands of wasp species divided into several families. The species that cause the most problems in Europe, North America, but also in the Southern Hemisphere (Australia, New-Zealand, Southern Africa) are the Common wasp (Vespula Vulgaris) and the German wasp (Vespula Germanica) of the Vespidae family. They are often referred to as yellowjackets, because of their black-and-yellow striped abdomen.
The yellowjacket wasps are social wasps and live in colonies consisting of workers, queens and males (drones). The colonies have an annual life-cycle with only the new produced queens surviving the winter. These queens have been inseminated by the males in late summer/ early autumn and store the sperm in a small sac until next spring when she needs it to fertilise new eggs.
By the time the new queens have mated and start looking for a sheltered place to hibernate, the old nest will be left abandoned. Wasps never return to an old nest.
In the first warm days of spring the queens emerge from their shelters and after a short period of feeding and exploring, they will start to build a small nest from chewed wood-fiber in which the first eggs are laid.
These eggs will hatch into larvae which will be fed by the queen with insects until they pupate and after around 40 days a first adult worker wasp emerges. From then on the queen will stay in the nest laying eggs for the rest of her life and the workers will take care of the queen, the larvae and the expansion of the nest.
The workers will forage for food for the larvae, which primarely feed on proteins and the larvae in their turn secrete a sugary material which is like candy to the workers (that's why they come back). This process lasts until the colony has its peak in the middle of summer (reaching a size of up to tens of thousands workers) and cells are constructed in the nest to house males and new queens.
Then the cycle starts all over again.Wasp nuisance and stings
By the time the wasp life cycle reaches its end in mid-summer, there are no new larvae. This means the wasps will no longer receive a reward in the nest, and look for it elsewhere. That's the time when wasps get agressive and fly to all sweet material they can find.
When wasps fly near you or land on your body stay calm and don't swing or strike them. Move slowly away to a safe area and do not crush the wasp since the released venom will trigger other wasps to attack! Please turn to a drugstore for information about what tot do when stung. Most people consider a sting pump (small vacuum pump) to be very effective. If you are allergic to wasp (or bee) stings, please consult a doctor.