Abstract.

The genus Declana contains some of the most beautiful of New Zealand moths. They are not, however, generally decked in gaudy or vivid colours, but owe their attractiveness to a pleasing arrangement of white or brown and grey. When resting on tree-trunks amongst lichen and moss they would be quite inconspicuous, and, as they are chiefly forest-frequenting forms, their colouring is probably highly Protective. Being nocturnal insects, they are not liable to much persecution from birds, though when found in the daytime they are eaten with relish. One member of the genus, however—D. glacialis Huds.—differs altogether from the others, and is, I believe, an example—the only one known at present among our native moths—of protective mimicry.

D. glaciulis, unlike any of its congeners, is brightly coloured, orange and red predominating. It is, I have no doubt, mimetic of the genus Metacrias. Of this genus we have three forms. They are all black and orange or black and red. They fly by day in the hottest sunshine, and when on the wing they appear to be bright yellow or reddish insects. They are, I believe, nauseous in taste; birds do not appear to attack them, and I have seen them untouched in spiders' webs. Declanae in general are quite opposite in appearance and habit to Metacrias, yet we find that D. glacialis has acquired a singular resemblance to the latter genus. It flies by day: Mr. Hudson found it flying commonly in bright sunshine at Mount Cook, and Messrs. Oliver and Pasco met with it under similar circumstances on Ben Lomond, Wakatipu. On the wing the markings will not be noticeable, and it will appear of the same reddish type as Metacrias. So unlike a typical Declana and so superficially like a Metacrias is the species that its describer, Mr. G. V. Hudson, had placed it in the latter genus, and only discovered the error by an examination of the wing-nervures, which are quite different in the two genera. There is, I think, a very strong presumption that Declana glacialis is mimetic of the genus Metacrias, though not perhaps of any particular species of that genus.