Elachista demogenes is a moth in the family Elachistidae. It was described by Edward Meyrick in 1897. It is found in Australia, where it has been recorded from South Australia.

The wingspan is 7–8 mm (0.28–0.31 in). The forewings are pale grey, irrorated with dark fuscous, sometimes with a suffusion of black irroration towards the dorsum anteriorly and toward the costa posteriorly. The plical and second discal stigmata are black. The hindwings are grey.

...