Merimnetria mendax is a moth of the Gelechiidae family. It is endemic to Kauai, Hawaii. The wingspan is 10-12 mm. The forewings are pale fawn-ocherous, profusely sprinkled and minutely mottled with fawn-brown, almost obliterating the paler ground color, a few blackish specks along the costa, especially before the middle. The hindwings are pale gray.