11 described species and a few undescribed
Larvae feed on seeds of goldenrods (Solidago) and sometimes asters.
The first instar larva feeds in the ovules without a case. The case is made by the second or third instar (it is not known which), and is very flimsy at first. It gets progressively enlarged as the larva grows, and pappus is often attached to the outside. Larvae mature late in the season with the seeds of their host. When feeding is completed, they move down to the ground and find a suitable place to attach their case and overwinter. The adults emerge the following year, usually in synchrony with the flowering of their host because they lay their eggs in the flowers.
According to JF Landry, the Coleophora duplicis complex and comprises the following species: acuminatoides, bidens, dextrella, duplicis, ericoides, intermediella, nemorella, puberuloides, rugosae, subapicis, triplicis. Species identification requires examination of genitalia; these species cannot be differentiated based on larvae, larval cases, or external features of adults. The larval cases of these species are all roughly cigar-shaped with a trivalved anal end (the non-feeding end where the frass pellets are expelled).
The information on this guide page was taken from JF Landry's note to MJ Hatfield here