Wasps eat a variety of foods depending on their species and the season:
Adult wasps
Both social and solitary adult wasps eat sugars, such as flower nectar, honeydew, and the sugary liquid produced by their larvae. They also eat fruit, and in the fall, their diets may include garbage, sugary snacks, soda, and meat.
Larvae
Larvae eat killed and chopped-up insects. Velvet ants lay their eggs on the pupae of other species, and when the eggs hatch, the young wasps eat their host.
Bald-faced hornets
These wasps eat fruit juices and nectar.
Yellow jackets
These wasps eat human food, including meats, as well as other insects and spiders.
Wasps are attracted to picnics and sugary foods, and you may find them fighting over your cut fruit, soda, juice, or alcohol. In the fall, when flower food sources dwindle, wasps may search for food around your backyard.