Macrosaccus neomexicanus is a moth of the family Gracillariidae.

The larvae feed on Robinia neomexicana.

The mine begins as a relatively short, serpentine track which enlarges to an elongate-oval, whitish blotch located on the underside of the leaflet.

As the larva develops and begins laying down silk, the mine becomes strongly tentiform, causing the upper surface to roll over.

This article relating to moths in the subfamily Lithocolletinae is a stub.