i got thinking of this word again and went looking on Google Books. Found citations not entomological, but botanical. The Botanical Register, 1817, describes a gloxinia bloom (with a kind of poetry):
Style white, ascendent, an inch long, tubular, bearded at the base : stigma hiant, broadest crossways, frosted within.
another text, Principia Botanica: Or, Beginnings of Botany from 1960:
... in which the ovary remains hiant into the fruit stage ; and in early ontogeny many ovaries are hiant), and another genus already technically angiospermous by the ovary closing, and the style being already fully formed.