Beneficial Because:
Adult hoverflies feed on flower nectar and help pollinate some crops, but it is the larvae that are important predators in the garden. The tiny, nearly invisible slug-like larvae scour the undersides of plant leaves for aphids, and eat them as their primary food source. They can be seen with a 10x magnifying glass.
Food and Habitat:
Hoverflies that come to your garden in search of flower nectar will also look for plants that are infested with aphids, and scatter their eggs on leaves where young aphids are hatching.
Attracting More:
Grow plenty of flowers with small florets such as sweet alyssum and members of the carrot family. Tolerate small aphid outbreaks in spring to help support a thriving summer population of hoverflies.