The most commonly known wasps are yellowjackets and hornets. These typically live together in a nest with an egg-laying queen and non-reproducing workers. The majority of wasp species are solitary, with each adult female living and breeding independently. Wasps play many ecological roles. Some are predators or pollinators, whether to feed themselves or to provision their nests. Many are kleptoparasites, laying eggs in the nests of other wasps. Many of the solitary wasps are parasitoidal, meaning they lay eggs on or in other insects (any life stage from egg to adult) and often provision their own nests with such hosts. Unlike true parasites, the wasp larvae eventually kill their hosts. Solitary wasps parasitize almost every pest insect, making wasps valuable in horticulture for biological pest control of species such as whitefly in tomatoes and other crops.