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Elachista
''For the genus of Chordariaceae brown algae, see Elachista (alga). As invalidly described by V. Kollar in 1832, Elachista refers to the Lyonetiidae moth genus '' Lyonetia.

Elachista is a genus of gelechioid moths. It is the type genus of the grass-miner moth family (Elachistidae). This family is sometimes (in particular in older sources) circumscribed very loosely, including for example the Agonoxenidae and Ethmiidae which seem to be quite distinct among the Gelechioidea, as well as other lineages which are widely held to be closer to Oecophora than to Elachista and are thus placed in the concealer moth family Oecophoridae here.

These grass-miners are very small moths with the " feathery" hindwings characteristic of their family. They are essentially found worldwide, except in very cold places and on some oceanic islands; as usual for Gelechioidea, they are most common in the Palearctic however. They usually have at least one, sometimes as many as three light bands running from leading to trailing edge of their forewing uppersides. Some species, however, have upper forewings that are mostly white.