NATURE NOTES

New Zealand Herald, Volume LXX, Issue 21467, 15 April 1933, Page 1 (Supplement)

NATURE NOTES

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

MOTH'S LONG PROBOSCIS

A few weeks ago correspondents drew attention to two notable features of the hawk-moth, Sphinx convolvuli. The features described are its exceptional power of flight and its conspicuousness in its caterpillar stage, when it is about 3in. long, bright green or light yellow, and when it wears a strange reddish horn on the last segment of its body. Mr. C. H. Taylor, Kaiinata, near Greymouth, has sent an individual moth, with an inquiry as to another feature. It is "a trunk fully 6in. long, curled up like a watch spring, and fitting into place under the head." This remarkable probosicis is a tube, or two tubes, which, interlocking, form a third tube. In its perfect stage, a moth or butterfly abandons the vegetarianism it observes strictly when it is merely a caterpillar. As an adult, living in the air and breathing the scented atmosphere among flowers that beautify fields, pastures, roadsides and gardens, it sips nectar from the blossoms. In the hawkmoth, nectar is sucked up through the proboscis by the action of a bladder in the head. Muscles in the two outer tubes coil and uncoil the proboscis, extending it to its full length, and then it is thrust deep into a calyx from which the hawk-moth, with joy, draws nectar. The outer tubes have tiny airtubes and, at their tips, pimples believed to be organs of taste. Most moths and all butterflies have spiral trunks made on this principle. There are some families of moths in which the' organ is vestigial. As perfect insects, these moths take no food. They seem to rely upon reserves of food stored up when they were caterpillars, greedy, voracious and insatiable. Perhaps even more interesting than its proboscis are a butterfly's antennae or feelers. A searching examination of the antennae • has disclosed in them innumerable microscopical pits. Each pit contains bristles, believed to be associated with the sense of smell or of touch. It has been stated that, in a butterfly or in a moth, these senses may be developed to a degree far surpassing anything with which people are familiar. An English entomologist, Mr. N. D. Riley, believes that a butterfly's sense of touch may be so delicate as to appreciate changes of air-pressure when the butterfly approaches solid objects and that its smell may be so keen as to account for established facts tnat seem improbable on the face of it. Tests of moths and butterflies' senses have had strange results. The insects have been undisturbed by loud noises, but the snapping of twigs and the gentle rustling of leaves at night have sent masses of them off in a fright. Butterflies on a verandah in Africa took hardly any notice when a rifle was fired close to them. A slight rustling noise put them to flight. The conclusion reached by Mr. Riley is that butterflies have some sort of ears, probably capable of appreciating a range of vibrations that differ from those recorded by human ears. Mr. C. B. Walker, Symonds Street, Onehunga, has described an interesting habit which, he states, he observed in a big, fat, pea-green hawk-moth caterpillar. On a caterpillar being pricked with a needle, the peculiar horn on the last section of the body bent forward. A pink whip was shot out of the horn and struck the place pricked with the needle, quickly disappearing into the horn again. The organ is about as thick as a pine-needle and bends as the blow falls like a whip. Mr. Walker suggests that this is the caterpillar's defence against ichneumon-flies. Females of these notorious parasites prick the caterpillars' soft bodies with their long, slender, flexible, threadlike, egglaying instruments. The ichneumons' eggs are deposited in the punctures. On hatching, the young ichneumons feed on the caterpillars' warm flesh and juices, imposing upon them a horrible lingering death. This is true parasitism, which is rare in some groups of the lower animals, but is common in insects. Some creatures seem to have deliberately developed characters to protect themselves against parasites that favour them particularly with undesirable attention. Tough, armoured, or slippery skins, or the secretion of a mucus that drives parasites away, are among the defensive methods. In the case of an ichneumon and a caterpillar, it is not to the parasite's interest, or to the interest of its progeny, that the victim should die immediately. Fresh food is required for the young ichneumons as soon as they hatch from the eggs. It is provided in the bodies of the living caterpillars. Wasps go one better than ichneumons by stupefying spiders before placing them in celis that contain the wasps' eggs. Parasitism is a complicated feature of animal life. One of its strangest features is that 0110 species of insect habitually parasitises another species of insect, which may parasitise a third species. This is called hyper-parasitism. There may be a third, even a fourth, stage of parasitism. There probably is no species of creature, from the humblest up to man, that is not attacked by parasites, some of them merely irritating and annoying, some fatal and ruthlessly cruel.* The horntail borer, since its accidental introduction into New Zealand not very long ago, has spread so far over the Dominion as to alarm foresters and sawmillers. The presence of this large borer from over the water is undesirable, but it should be less dreaded than the common house-borer, which, although small, does greater damage than can be assessed in pounds, shillings and pence. The horntail borer leaves houses and furniture aloue. Its white, fleshy grubs attack old logs and timber freshly felled, but, on Dr. 11. J. Tillyard's authority, not healthy, growing trees. The horntail borer, Sirex juvencus, is a handsome insect. The sexes wear different colours, but the female may be distinguished by her highly efficient egg-laying instrument, with which she bores into wood. A description of this work has been sent by Miss V. Wiseman, Ranfurly Road, Epsom. Her letter is as follows: " When staying at Deep Creek this summer we saw a remarkable insect, with two pairs of wings spread down over its back. The lower part of the body we found to be a kind of sheath. Along it there rested a fine saw, connected by a hinge to the centre of the body. The insect clung by its legs in an inverted position to a log. It began to make holes in the wood between the bark. Its method was interesting to watch. Doubling up its whole body, and feeling for the wood, it pressed its little saw in and worked the saw up and down. We noticed that the saw was composed of two sections, working side by side. During ten or fifteen minutes while we watched, the insect made several holes. We did not see it place any eggs in the holes."