Larva: feeds in two generations (August to April and again during July and August). In the autumn, and after overwintering in a hibernaculum, feeds on the basal leaves of both Rumex species, either folding the leaf edge into a slight tube or, sometimes, windowing the leaf from below. On Rumex acetosa in the autumn, has been found in a long, linear, often sinuous mine, with sometimes more than one mine on a leaf. Also reported in a silken gallery spun on the upper part of the roots, or along the stem, or among the seeds. See also note on a beetle larva in the 'Similar Species' section below. For reference details, see 'Publications - Published Papers - Teleiopsis diffinis - Heckford and Beavan, 2019'. It seems that feeding habits of the summer larvae have not been observed.
Adult: most frequently encountered at light, sometimes in good numbers, flies late in the evening, can be swept or smoked from amongst the foodplant during the day. Has been noted flying over heather and amongst Teucrium scorodonia (wood sage).