A large family of medium-sized grey flies. Most species live near fresh or salt water. There is a large variety of life styles among the larvae. All species of the extensive genus Hydrellia are miners of (semi) aquatic plants, mainly grasses and Potamogetonaceae (Deonier, 1998a).
The most important species is the polyphagous leafminer Hydrellia griseola, that in tropical regions can be a pest on rice. The larval mandible has but one tooth. The forward pointing arm of the cephalic skeleton is larger than ther rearward pointing arms. The elongated egg is deposited to the outside of a leaf and remains visible at the start of the mine. Clanoneurum cimiciforme mines in some halophytes.