Stibaroma melanotoxa, the grey-caped line-moth, is a species of moth of the family Geometridae first described by Edward Guest in 1887.

The original description by Guest, done on a male specimen, mentions "a handsome, silvery-grey moth".

There is a narrow but sharply defined black line, very acutely angled outwards, one-fourth of the way along the forewing.

[2] Larvae of S. melanotoxa grow up to 4 cm in length, are rough in appearance and range from orange to red-brown in colour.

During the daytime, they either stretch out and press against a stem, or loop the front part of the body such that the head and thorax lie on top of the abdomen.