Host plants
The leafminer flies which belong to the genus Liriomyza, especially the species L. trifolii, L. bryoniae and L. huidobrensis, are cosmopolitan pests of vegetables and other field-crops such as tomatoes, cucumbers, celery, carrots, potatoes, alfalfa, melons and watermelons, as well as ornamentals such as Gypsophila, Chrysanthemum and Gerbera.

Morphology and biology
Adults of different leafminer species are difficult to distinguish. They are relatively small black flies (2.5 mm long) with yellow spots on the thorax between the wings. Adult leafminers feed on the leaf sap produced when the female fly inserts her ovipositor into the upper leaf surface to seek a suitable site for inserting an egg within the tissue. Only some of the punctures are eventually chosen as egg-laying sites.

Biology
Each female lays more than 100 eggs during a 2-3 week lifetime. After about a week the eggs hatch into small larvae that tunnel within the leaf tissue. Each larva forms a pale white tunnel or mine. The larvae feed for up to 10 days during which they go through three instars. As the larva becomes larger, the mine also becomes larger, longer and broader. Mature larvae emerge from the mines and fall to the ground where they pupate safely. After about 9 days, adult flies emerge to repeat the cycle.

The leafminer is capable of breeding throughout the year especially in heated greenhouses. It is an extremely virulent pest and when in outbreak proportions it may severely disrupt photosynthesis in the plant leaves that eventually dry out and defoliate.