Most of the mean, aggressive reputation wasps have seems to come almost entirely from hornets, including yellow jackets, and that’s almost entirely because it’s easy to invade their territory without realizing it. Other animals may hear or smell them and know to steer clear.
Even then, hornets will generally respect you if you respect them. Other nest-building wasps, like paper wasps, are especially mellow and won’t attack unless they truly believe you’re after their young. Different species have different ways of trying to warn you off before they will resort to stinging, which is a desperate measure, since it can result in them dying and a predator attacking the whole nest anyway.
The main purpose of a wasp’s sting is really for hunting prey, and that’s what they’re best at. A colony of paper wasps, hornets or yellow jackets regulates the insect and arachnid populations over a wide area, critically necessary to the health of a local ecosystem. Caterpillars in particular are a major prey for carnivorous wasps, and otherwise easily overwhelm and devour the foliage of whole trees.
And sure, other predators contribute to this, but wasps are definitely one of the most important, especially since the majority of them are specialized parasites who lay their eggs in specific insect species. Plant life actually evolved chemical signals just to communicate with different types of wasp, summoning their aid to take care of different leaf-eaters.
Of course, plant eating insects themselves are also necessary. Without their steady activity, plants can overgrow until they smother one another, break out in diseases or deplete the soil. Nobody ever really talks about the fact that plant life needs its own population control to thrive, just like animal life.
Both the herbivorous insects and the wasps that destroy them need to exist in a balance for everything to run smoothly.
I’m sorry if this turns into a solid text wall, the new tumblr system likes to remove spacing.