NATURE NOTES.

New Zealand Herald, Volume LXIX, Issue 21112, 20 February 1932, Page 1 (Supplement)

NATURE NOTES.

STICK-INSECTS.

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

Having found a stick-insect about five inches and a-lialf long, Mrs. A. Farrell, Owen River, Murchison County, Nelson, asks if it is an unusual length. It doubtless is a member of New Zealand's! largest species of stick-insects, Acanthoderus horridus, an ugly, spiny creature, as its official title implies. Five inches or six inches is the regulation length for an adult. It is nob a pigmy, but it is small compared with some members of the family in Australia, which are eight, nine and ten inches long, the largest stickinsects in the world. As a whole, stickinsects are among the strongest creature:! on earth. Resembling sticks, twigs, grassstems, mosses or pieces of lichen-covered bark, they are startlingly like common products of the vegetable kingdom, and in variety of form they have few rivals in their own kingdom. The numbers of this species is small compared with the numbers in large insect families, but no other family probably equals them in multiplicity of form and diversity of appearance. All New Zealand's species of stickinsects are wingless. This defect adds to their remarkable resemblance to twigs. Their thin legs often are at right angles to the body, like shoots from twigs. Stickinsects are related to the bright green mantises. These find protection from enemies in their resemblance to green leaves, almost to the same degree as stickinsects are protected by their resemblance to twigs. The forelegs and claws of_ a mantis are adapted to seizing other insects, on which they live. Stick-insects are strict vegetarians and their limbs are not made for attack. Although they are voracious, a pair destroying much foliage, no complaints of their ravages have been made in New Zealand. Australia, where stick-insects and their relatives, the leafinsects, reach their highest development, suffers from their presence. In parts of the Commonwealth they denude gum-trees of all foliage. Dead and dying insects have been found beneath the trees almost in heaps. The male stick-insects are much smaller than the females, also slenderer and less spiny. Besides this, most individuals found are females. Males are rare. A species of Indian stick-insect has been reared in captivity in large numbers in England. Among many thousands born in England there has not been one male recorded. Yet the females continue to produce fertile eggs. Mr. E. Step, an England entomologist, states that breeders of these insects in England, after supplying all their friends •with eggs, or young, soon do not know what to do with the surplus. Close observers of stick-insects report that the insects' Only occupation seems to be feeding, pursued mainly at night. Mr. G. V. Hudson, who has watched Acanthoderus horridus, states that it is taken at night, when it can be readily discovered feeding on the leaves of shrubs. As soon as a light is turned .on to it, it becomes absolutely motionless. Large numbers of little stick-insects, according to Mr. Hudson, may be seen on parasitical ferns that cover tree-stems in New Zealand forests. He describes them as strange little creatures, their antics when they mimic twigs being very amusing. He recommends any New Zealander who wishes to study a fascinating branch of entomology, almost untouched, to keep stick-insects in captivity and watch their developments and their habits. Students probably will find that the life-histories of New Zealand insects are much the same as life-histories of stick-insects elsewhere. Each egg of an Indian stick-insect, Dixippus, is enclosed in a horny case, which might easily be mistaken for the seed of a plant of the pea family.' On one side of the case there is a_ scar that resembles the scar on the leguminous seed, marking the attachment to the pod. When a young Dixippus hatches,, it pushes off the lid of its case and escapes from its prison into the world. Growing rapidly, it casts its skin several times before it becomes a grown-up. In moulting there is difficulty sometimes in getting one limb free from the old skin, and the limb breaks off. If this early in life, on a reduced scale a new limb is disclosed at the following moult. When yet another moult occurs, the limb is closer in size to the other limbs. If the accident happens later in life, Mr. Step finds, there are not sufficient moults for the process to be completed. The eggs are laid on the ground. Leaving the egg, and wearing homely brown, a young stick-insect climbs a stem, feeds on the leaves and puts on a coat of green. Later, it may change into brown again, or into a dull grey, to make its costume match the colour of a twig on which it rests. In the Tropics some stick-insects wear brown mottled with green, resembling liverworts that cover jungle stems and leaves. Several naturalists have been surprised at the resemblance between the history of a stick-insect's egg and the history of a seed. The eggs are shed like seeds. They are dropped loosely, and remain on tlfie ground without any covering except their cases. Another remarkable feature of a stick-insect's life-story is that, as soon as a young one leaves, its eggs, its body expands prodigiously, the expansion affecting the parts of the body unequally. The expansion is so great that it seems almost impossible for the egg to have contained the creature. No fossil stick-insects have been found in New Zealand. In other places ancient members of the family were entombed in amber. In carboniferous rock, laid down perhaps 200,000,000 years ago, there are the remains of gigantic insects that may have been connected with living stickinsects. They -were about twenty inches long, horrid, but, no doubt, harmless, falling victims to the equally gigantic and more formidable contemporary dragonflies, which measured two feet across their oxpanded wings. The rare, caterpillar-like, slow-moving, light-shunning, publicity-avoiding, inconspicuous, bluish-grey peripatus is believed to bo the survivor of an ancient type of insect, a living link between tho worms and a group that includes the insects, the spiders and their allies. When the Challenger Scientific Expedition was in Wellington fifty-seven years ago, members of tho expedition collected almost fifty specimens of peripatus in the Hutt Valley. Some years later tho first living peripatus were sent from New Zealand to London by Mr. Noel Barraud, of Wellington. The first two lots died soon after the vessel 011 which thev were consigned reached Rio do Janeiro, "in the third attempt. Mr. E. ,T. Evans, chief officer of the Tamui, found a place near tho cold chamber where tho atmosphere in the Tropics was not too high for the distinguished travellers. Thev lived to see England, and were handed over to Professor Adam Sedgwick, who wrote a classical monograph on the peripatus family. To him, all the members of the family, so far from being repulsive, were creatures of exceptional beauty. Mr. F. J. O'Regan, solicitor, of Wellington, when living on tho West Coast, says he saw a tui wantonly done to death by a kingfisher. The tui was sitting on a withered limb singing carelessly, with feathers ruffled. The kingfisher, which sat directly above, suddenly dropped quickly and struck the tui a savage blow on the head, causing it to fall to the ground, hopelessly wounded. An examination showed that its head had been crushed. The shocking deed, evidently, was merely the expression of a devilish impulse to kill, as the slayer made no effort to keep its victim. It flow away, happy in the knowledge that it had destroyed one of the brightest and most talented dwellers in tho forest.