Erechthias crypsimima is a species of moth in the family Tineidae. It was described by Edward Meyrick in 1920. This species is endemic to New Zealand and has been observed in the North Island. This species inhabits native forest and has been observed in Nothofagus fusca forest. The larvae likely feed on either deceased plant detritus or tough leaves of plants such as palms or flax. Adults are on the wing commonly from January to March. During the day, adults are known to rest on tree trunks where the moth's colouration helps provide protection by camouflaging the moth.

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