It’s August, and you’re about to enjoy a lovely picnic in the sunshine with your friends. But then, a vexatious buzz signals the arrival of a tiny gatecrasher, who, after terrifying the weaker members of the group, makes a beeline for your iced tea. But why do wasps suddenly appear in greater numbers in late summer, persistently preying upon our sugary snacks? Well, it’s all to do with how adult wasps feed and how their colonies change throughout the year.

Despite their antisocial presence at barbecues and picnics, wasps are social insects, living and working together in large colonies. Most wasps are female workers that can’t reproduce, so they spend their time raising their sisters and improving the structure of the nest. These workers are produced by a single queen wasp, who founded the colony in spring.

Why armadas of wasps descend from the skies in late summer has to do with food, notes Sussex Wildlife Trust. As worker wasps have such tiny waists, they struggle to digest the tasty soft-bodied insects that they collect to feed the colony’s young. Therefore, they need an alternative – when they feed the food to the larvae, the grubs produce a sugary spit that the worker wasps can drink. Delicious.

The colony grows and grows throughout the summer months, but then the queen switches from producing female workers to producing fertile males and other queens. These individuals then fly off to reproduce and start new colonies. The new queens hibernate over winter and initiate a colony in springtime.  

After producing her new heirs, the queen stops laying eggs completely, meaning that the worker wasps have nothing to eat as there are no more larvae. Therefore, the wasps head out into the wilderness in search of other sugary substances to drink. Naturally, they go for rotting fruit, but unfortunately a jam sandwich or a can of coke will tempt them just as much.

The wasps’ propensity to consume rotting fruit also has another unwanted effect. The fermented fruit can actually make them drunk, meaning that the insects descending upon your dinner might seem a little rowdier than your average T-total early summer wasp.

But these little grievances don’t last long. Colder temperatures cause the entire colony to die off – including the original queen – leaving only the new, hibernating queens to continue the species with brand-new colonies come the spring.   

While they might be a nuisance, wasps are important pollinators and great at getting rid of annoying pests that destroy our plants. So, if an unwelcome wasp does attend your picnic, please don't squish it.  

[H/T: Sussex Wildlife Trust]