Monochroa monactis is a moth of the Gelechiidae family. It was described by Meyrick in 1923. It is found in North America, where it has been recorded from southern Ontario and North Carolina. The wingspan is 9-11 mm. The forewings are whitish, sprinkled grey except towards the costa anteriorly, suffused grey on the posterior third. The plical and second discal stigmata are black and distinct and there is a very oblique whitish striga from the costa at two-thirds to the termen beneath the apex, preceded and followed on the costa by dark grey suffusion, between this and the apex three or four whitish costal dots separated by dark grey suffusion. The hindwings are light grey.