There are concrete reasons for why people have come to dislike wasps. They're highly territorial and easily roused in defense of their nests, descending in a stinging swarm upon anyone they feel is a threat to their home and larvae — and since it's far from rare for them to build their nests in places like fruit orchards or under the eaves of houses, where people can easily anger them by mistake, people quickly learned to associated the strikingly colored flying insects and their distinctive paper nests with angry swarms and impending pain.
This is especially notable when contrasted with bees. Due to their similar appearances, colonial natures, abilities and behaviors, wasps and bees are easy to associate and compare with each other. Bees produce honey and are thus useful to humans: a beehive is either a welcome discovery in the woods or a beekeeper's carefully farmed possession. Wasps, however, produce nothing of significant value to humans, and the discovery of a wasp nest does not thus offer anything beyond painful stings and a great deal of trouble. Bees also tend to be somewhat less aggressive, as their barbed stings remain fatally embedded in their victims, thus making bees less likely to sting their targets than wasps tend to be. Exceptions to this occur in the form of the smooth-stinged bumblebees and the notoriously aggressive Africanized bees, but the former live in small colonies and are not especially aggressive while the latter are, in terms of human history, a fairly recent development.
A dichotomy thus arises where bees, alongside ants, have come to symbolize selflessness, hard work and the fruits thereof, whereas wasps come to be seen as aggressive robbers and predators. When ants and bees appear as protagonists, wasps are common antagonists, menacing their fellow eusocial insects with fierce raids, invasions and attacks. The opposite — heroic wasps faced off against villainous bees — almost never happens.
Many wasps are also predators by nature, and, as fiction often reminds us, Predators Are Mean.
In terms of physical appearance, fictional wasps typically have the classic black-and-yellow coloration of the yellowjackets
and of some hornets, and the paper nests and physical build of these two groups as well. Real-life wasps are an immensely diverse group, including numerous different strains of insect with distinct appearances and lifestyles — some wasps are solitary, some are parasitic and some build nests out of mud, many have distinctive colorations that include white, red and green alongside or instead of black and yellow, and both ants and bees are technically specialized branches of the greater wasp family — but don't expect to see this diversity referenced in fiction terribly often.
