Dictionary.net

Any one of numerous species of handsomely colored butterflies belonging to Vanessa and allied genera. Many of these species have the edges of the wings irregularly scalloped.

i.e. Phanessa (from Phanes, a mystic divinity in the Orphic rites, known also as Eros). (Entom.) Gen. of butterfly, brightly coloured ; as the Peacock B. Fam. Nymphalidae.

So styled by Dean Swift, who exerted a kind of enchantment over her as he had clone over Stella ; Hester Vanhomrigh, the daughter of a London merchant, who died of a broken heart, 1723. See Stella.