M. hudsoni is very similar in appearance to its near relatives M. fusca and M. fallax but can be distinguished via differences in male genitalia.

[2] The holotype specimen was collected at Ōtari-Wilton's Bush in Wellington in March 1922 by George Hudson and is held at the Museum of New Zealand Te Papa Tongarewa.

[2] M. hudsoni is a small moth with a dark brown appearance with ochreous coloured scales scattered over the forewings.

[2] The antennae of the adult of this species is ochreous yellow and the forewings are greater than 3.4 mm in length.

[2] This species prefers to live in cool shaded areas either deep in native forest or alongside rivers and streams.