Hodges (1974) described genus Dafa for formosella and noted that Epicallima is an invalid replacement name for Callima. It must be noted that no explanation for moving formosella back to Epicallima or retaining the Epicallima name has been found in the literature afterward. But much recent literature on the Eurasian Oecophorid fauna continues using Epicallima instead of Callima and maintains formosella in Epicallima rather than Dafa.

Pohl & Landry in Pohl & Nanz 2023 and Moth Photographers Group have reviewed the taxonomy and reiterated the conclusion of Hodges that formosella belongs in Dafa. BugGuide follows these sources. And so formosella is moved back to Dafa as its latest placement.

Hodges 1974: http://wedgefoundation.org/6_2.asp, free PDF at http://wedgefoundation.org/publications_paypal.asp
Pohl & Nanz 2023: http://wedgefoundation.org/MONA2.asp
MPG: https://mothphotographersgroup.msstate.edu/species.php?hodges=1048