Stephen,
According to "Above Flanders' Fields" his name is Joseph Vuylsteke. He received his wings on 13 August 1918. "Steke" as he was known, was first posted to the 4me Escadrille on 8 September. He was posted to the Groupe de Chasse on 16 October, as a substitute for the loss of
Willy Coppens two days before, where Vuylsteke flew his first offensive patrol on the 22nd. Steke flew only 15 sorties, but was engaged in another five aerial combats, four of them attacks on observation balloons. One was destroyed (1 Nov.) for which he received the Croix de Guerre with Palme.
Though his plane -HD68- bore the 11me Escadrille's paper bird insignia, all his patrols were flown with 9me Escadrille.
Why he chose the English name "Butterfly" I don't know.
Jos