Hoverfly [en]
According to Wikipedia "
Many species of hoverfly larvae prey upon pest insects, including aphids and the leafhoppers which spread some diseases like curly top. Therefore they are seen in biocontrol as a natural means of reducing the levels of pests.

Gardeners, therefore, will sometimes use companion plants to attract hoverflies. Those reputed to do so include alyssum, Iberis umbellata, statice, buckwheat, chamomile, parsley, and yarrow."

Syrphidae [fr]
D'après Wikipedia "Le syrphe est un allié naturel de l'homme dans sa lutte éternelle pour la subsistance : sa larve se nourrit de centaines de pucerons, qui dévorent nos récoltes. On plante, en bordure des champs, des phacelia pour nourrir les syrphes, dont les larves dévorent les pucerons, l'œillet d'Inde attire ce genre d'insecte aussi."