NATURE NOTES.

New Zealand Herald, Volume LXVIII, Issue 20768, 10 January 1931, Page 1 (Supplement)

NATURE NOTES.

A LITTLE IMPOSTOR.

BY J. DRUMMOND, F.L.S. F.Z.S

Small, delicate, fragile, pretty, and waspy, an insect sent by Mr. E. B. Weekes, of Tiriraukawa, Mataroa, Rangitikei County, is interesting for the reason that it represents a very common practice among inoffensive insects of posing as other insects notorious for their aggressiveness and powers to inflict injury. Mr. Weekes found his insect in the chrysalis stage in a mulberry twig. He kept the chrysalis in a jar until it developed into a perfect insect. Its gauzy wings, only three-quarters of an inch in expansion, are transparent, but are prettily tinged with black and orange yellow. The head is black. The body is black, belted with several yellowish-white rings. For all the world it looks like a small wasp. The trust is it is a moth, stingless, defenceless, and harmless as far a other inects are concerned.

Popularly, this insect is called the currant-borer. It has earned its name because, as a caterpillar, white with a pale brown head, it bores into the sterns of currant bushes and into the stems of other plants judging by Mr. Weekes' experience. From autumn until spring the caterpillar feeds on the pith of stems, which take on a sickly appearance and sometimes die. The perfect insect appears in December and January. It may be seen in all its delicate beauty sitting on the leaves of currant bushes, or on flowers near the bushes. Its official title is trochilium tipuliforme, but it belongs to a famous moth family known as the clear wings.

Members of the family are called clearwings because the main parts of both pairs of wings are devoid of scales. The family is not represented by any native New Zealand species. The currant-borer is the only species of the family known 10 be in the Dominion. The family is chiefly characteristic of the Northern Hemisphere, where they are many species. Some of them closely resemble stinging insects, notably wasps and hornets. Several reliable authorities believe that the resemblance is purposeful, the inoffensive insects, by their counterfeit, presentment', escaping the attention of at least some of their enemies.

Entomologists have gone so far as to give larger species of clearwings fanciful names, linking them up with members of the orders of the wasps and of the flies. Among these are two close English connections of the currant-borer, known as the hornet-moth and the lunar hornetmoth. - Even these popular names cannot stand strict criticism, as the species resemble wasps, not hornets. Mr. S. Step, an English entomologist, believes that these resemblances in nature—at, least very strange and hard to explain as merely accidental—are intended for protection. "Anybody not a nsituralist who may conte upon the hornet-moth as it sits quietly on a trunk," he states, " will be justified in thinking that it is a queen wasp. Not only is the general appearance that of a wasp, but the hind-body, instead of being puffy with its covering of long scales, as in most thick-bodied moths, has been reduced to so small a size that the appearance presented is that of the smooth, hard corselet of a wasp. In addition, hornet-moths curve the hind body in such a way that it becomes much more wasp-like than it would be if fully extended, as in other moths. The feelers are exactly the shape of the same organs of a wasp."

Evidence of the value of protective resemblance is found by Mr. Step in the case of the orange-tailed clearwing. Until 1829, it escaped notice as an iqsect of the Old Country. Until a few years ago it was regarded as rare. As a matter of fact, it always has been fairly plentiful. Its reputation for rareness rested on the fact that it resembles a wasp so closely that it imposed on butterfly hunters and moth hunters, who ignored it, under tho impression that it was not a moth. It is attacked by ichneumon-wasps, whoso order of insects it' mimics. Its imposture is not effective against those enemies, because they attack the moth in its caterpillar stage, when there is no pretence.

The latest contribution to the literature of the native crows is by Mr. F. G. Sparrow, Takaka, Nelson. He writes: " Fifty or sixty years ago. I worked for gold on a branch of the Takaka River. Several species of native birds, some of them extinct in the district now, came about looking for food. The South Island crow was the most plentiful of them all. I remember its blue-black plumage, a wattle near each side of the mouth, and the very strong legs and neck, well adapted for turning over pieces of rotten wood. Tho crows seemed to find all their food on the ground an in old rotten logs. They went forward with a long jump, in which they used their wings, short, but very strong. I never heard them utler a call or whistle, but they made a low grunting noise, like little pigs.

" The creek on which we worked was heavily timbered throughout its whole length. The crows seemed to range it from end to end. Although I was there one summer and had good opportunities to study natural history, I never saw a crow's nest or young. Since those days, men have been in that country digging, and it has been fairly well explored, but not a single crow has been seen there for many years. The country is in pretty much the same condition as it was in at the time I mentioned, and I know of no reason for the extinction of these largo birds, so plentiful in the past. It is ten years since I was there on the last occasion. The bush then was very quiet, depressing and desolate, very different from the days when crows, robins, wrens, bush-canaries, parrakeets and many other species were represented abundantly."

Mr. Sparrow's reference to the South Island bush-canary brings to mind the fact that this attractive native bird, sometimes called the yellow-head, still collects in cheerful, chatty parties in many parts of the South Island. For reasons that' have not been explained, it thrives where native crows have failed to retain their position. One of the busiest birds in New Zealand, it seems always to be searching the bark of trees for 'r.sects, or (urning over moss and leaves on the ground. It is sufficiently inquisitive, or friendly, to come close to a visitor to its green mansions; but its curiosity is soon satisfied, and in a few minutes it is off again attending to its own business. Moss, pressed tightly and interwoven with spider-web, is the material it usually select's for its nest, which may be found in the hollow trunk of a broadleaf tree or in a decaying black beech. The yellowhead has a sharp, strident note, and a quick and active demeanour that matches its alert mind. Its habits are' like thoso of its North Island cousin, the white head. They are distinguished superficially by their costumes, the northern bird wearing white where the southern bird wears .golden. The yellow head should not he confused with the yellow hammer, an introduced bird, which also wears a golden crown and a cape of cloth-qf-gold. and which, unlike the yellow head, flocks about stables and barns and in fields near homesteads.