While some Wasps are pests in and around the home and garden, there are many Wasps that are beneficial, including parasitoid and predatory Wasps.
A parasitoid Wasp is a female adult Wasp which lays an egg on, in or near a host such as a scales, caterpillars, whiteflies, mealybugs, flies, weevils, grasshoppers and other Wasps. The Wasp egg hatches into a grub-like larvae and feeds on it's host, eventually killing it. Wasp eggs which are laid inside the host, at the end of feeding, pupating and exiting, leave behind a skeletonised host body, a common example is mummified aphids. A very gruesome process, but effective nonetheless.
A predatory Wasp is a Wasp which catches, kills and feeds on it's prey, whether to feed on the prey itself or to feed the prey to it's young. Wasps feed on other animals such as caterpillars, moths, soft scales, and spiders.
Wasps can also be pollinators as they feed on nectar from flowers. Pollinators are a real asset for fruiting plants in the garden and are essential for the environment.