These wasps are related to hornets. They gather fibers from dead plants and wood and create nests made of a papery material when mixed with their saliva. These nests are generally a comb-like structure with cells for rearing brood (babies).
Though these wasps can be known for stings, they are not usually aggressive unless they are protecting their nests. They are also not scavengers such as yellow jackets, so they are less likely to aggravate your next picnic. However, they are fantastic pollinators and predators.
Typically most active spring through fall.
Like most insects, they are most abundant in tropical locations but can be found in temperate zones all over the world (except Antarctica).
These may show up in gardens with prime places for their nests or expansive food sources.
Paper wasps readily feed on nectar and pollen. They also hunt larger pests such as caterpillars, beetle larvae, and flies which are often fed to their young. Make sure to plant plenty of pollen/nectar producing plants such as goldenrod to keep these flying predators around. Minimal use of pesticides is also recommended.
The above recommendations should be ignored if you have an allergy to wasp stings. Paper wasps are known to cause anaphylactic shock in people that are allergic. That said, if you are not allergic, stings are rare but can be painful. If you do have these hanging around your plants, use caution when nearing nests to avoid any… well… ouchies.