At this time (up to mid July) of the year, wasps are not so disturbing as at the end of the summer. Currently, they are still busy with taking care for the next generation. Some are collecting pollens and some are getting water and the others are building the nest or defending it while the queen produces more and more eggs.
Like hornets or bees, most of the insects in a wasp-state are infertile females. They have a lot of work with collecting pollens for feeding the breed and hunting other insects as food for themselves. They are expanding, repairing and defending the nest. The only purpose of the males is copulating with a female to-become-queen and state-founder at a certain date in the later summer (in my region it’s often at the end of August or early September). After that event the state breaks into pieces: the males leave the nest and die, the fertilized young females also living the nest get inseminated and searching for a safe place to survive winter, even the old queen, the mother of the whole state, usually dies because of exhaustion from laying all the eggs (several thousand up to 50,000 during one summer). And the infertile females? They are now unemployed, because all of their duty was to prepare this one day when all the males and the fertile females are leaving the nest and starting to their wedding flight.
Without their necessities for caring for the state they are bored and have a lot of time to enjoy the rest of their lives. And, … for their entertainment, they are about to annoy the humans by disturbing the barbecues, taste cakes (i.e. plum or apple cake), soft-drinks and many, many more things.
Although, adult wasps eat other insects, they are still interested in everything sweet and in meat.