violet-tip

from The Century Dictionary.

• noun A handsome American butterfly, Polygonia interrogationis, whose wings are reddish with brown mottlings and violet tips. Its larva feeds on hop, elm, and nettle.

from the GNU version of the Collaborative International Dictionary of English.

• noun (Zoöl.) A very handsome American butterfly (Polygonia interrogationis). Its wings are mottled with various shades of red and brown and have violet tips.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun An American butterfly, Polygonia interrogationis, whose wings are mottled with various shades of red and brown and have violet tips.