[4][2] In 1875 Cajetan von Felder and Alois Friedrich Rogenhofer, thinking they were describing a new species, named it Platyptilus haasti.
[1] The lectotype specimen, collected in Nelson, is held at the Natural History Museum, London.
He described the larva: The larva, which feeds in the opening leaf and flower buds of Hebe salicifolia, is about 1 inch in length, fairly stout, slightly tapering at each end, with segments well defined; head small, greenish, mottled with brown; segment 2 with obscure ochreous dorsal plate; rest of body yellowish-green, darker on sides and under-surface; a broad, slightly irregular, deep red dorsal line from segment 3 to anal extremity; several slightly darker green subdorsal lines; warts minute, emitting short slender blackish bristles.
Hudson also stated that the larva of A. facatalis had black legs which appeared to be characteristic for this species.
In form it is very like the pupa of P. aeolodes; the dorsal appendages are slightly shorter and flatter, with a small spine projecting from the extremity of each; general colour rather dull reddish-brown, a little paler on ventral surface, and faintly mottled with darker brown; an obscure paler lateral line; abdomen with four rows of conspicuous whitish warts.
[12] Prior to pupation the larva will retract its head and move the anterior segments of its body in a humping action.
[12] The pupa is formed by the larva after it attaches itself to a leaf or twig with a silk pad, hanging head down.
[9] The adults of this species have been observed on the wing all year round but is more commonly seen in late summer and autumn.
[13] Research undertaken prior to the introduction of Trigonospila brevifacies into New Zealand as a bio control, indicated that this species of fly uses A. falcatalis as a larval host.