IN TOUCH WITH NATURE

Otago Daily Times, Issue 21772, 11 October 1932, Page 2

IN TOUCH WITH NATURE

DAYS OP OLD.

HUNDREDS OF MILLIONS OF YEARS AGO.

By J, Drummond, F.L.S., F.Z.S.

Stating that he was interested in an article in this column bn the ancient lineage of insects, Mr G. V. Hudson, Karori, Wellington, author of “New Zealand , Moths antj Butterflies,” a large volume, beautifully illustrated with coloured plates, has supplied the following additional item on these creatures’ ancestry;—“ Fossil insects are abundant in the Upper Carboniferous rocks in North America and in France; and modern geologists estimate that formation to be 270,000,000 years old.” The Carboniferous Period is well marked in many countries. In New Zealand it is a blank: the coal measures in this Dominion were laid down much later than Carboniferous times. No Carboniferous insects have been reported from New Zealand, probably never will be. Fossils discovered elsewhere seem to show that insects which lived in thpso wild days 270,000,000 years ago, with a few exceptions, were not greatly different from the insects that compose about three-fourths of the animal kingdom in our own times; but Carboniferous dragonflies with a body more than a foot long and a wing-spread of two feet may be accepted as evidence that some early insects were much bigger than any insects present in the world now.

The little silvcrfish, which has been introduced into New Zealand from the Old Country, and makes its way into New Zealand houses, belongs to a group ot wingless insects believed, to be the most primitive existing insects and the earliest of which there is any knowledge._ Mr N. D. Riley, an English entomologist, describes members of the group as active creatures, dwelling usually in obscure places under stones or dead leaves, and mostly so small as to escape much attention. They have no traces of wings, have no metamorphosis, and, in general appearance, suggest the immature forms of other insects, rather than adult forms. He finds in two features of their mouthparts marked affinity with the crustaceans, which include the shrimps, crabs, and lobsters, and which, although called the insects of the sea, are classed lower than insects in the scale of life.

Going back in speculative mood to a time before the Carboniferous Period, Dr R, J. Tillyard states: “Ancestors of plant-life lived in the sea. The insects ancestors almost certainly lived in the sea alongside the. plants’ ancestors, probably feeding on them. When the plants ' came out of the sea and began to live on the land they had to adapt themselves to their fresh conditions of life. It does not require a great stretch of imagination to see the first true insects adapting themselves to the changed condition© in the same way. It is highly probable that the true insects’ first step in evolution was taken because of their association with the speial group of plants that first made good their footing on dry land. From this simple beginning, through many million© of years, a closer and closer association of two great groups, plants and insects, has developed gradually, culminating in some of the most perfect and wonderful adaptations of living organisms to one another for mutual benefit,” The earliest insects known, according to Dr L. O. Howard, an eminent American entomologist, in “ The Insect Menace,” published by the Century Company, New York, lived with vast forests of nonflowering plants. The large forms referred to in this article survived for a long time. When they were blotted out, the cockroach type arose. Judging by their remains in the rocks, the cockroaches almost overran everything. With the cooling of the climate, ages later, smaller insects developed until they swarmed in multitudes. To Dr Howard insects seem the most permanent and persistent type of life evolved on the world. He is very emphatic, and, it must be confessed, disconcerting: “ I am inclined to think, as Maeterlinck does, that insects are our rivals on earth, and perhaps our successors, only I would leave out the 'perhaps’ and accept Dr W. J. Holland’s prophecy that the last living thing ori the globe will be some active insect sitting on a dead lichen that will represent the last of the life' of the plants.” If these speculations-have a solid basis, insects came in with the plants, and will go out with them.

Dr Howard, not very seriously, it is hoped, fears that there may come a terrible cataclysm in which the human species, mere upstarts compared with the insects, may be wiped out. with many other species of higher animals, and-with the flowering plants, making it necessary for long-suffering Nature to begin to evolve something to take their place; but he feels that it is safe to predict “that most of the insects, or such of them as are not dependent on crops carefully raised for them by human beings, or such of them as are not dependent on flowers, will survive the conditions that destroy hs and others.” To support this, he recalls the fact that the insects, since the Paleozoic Era, - have gone through cataclysm after cataclysm. When they are subdued, he concludes, it will be safe for a possible historian on Mars to say: “ This is the end of the world.” He modifies it all by admitting that this line of thought is somewhat futile. His excuse is that he follows it only to indicate boldly the nature of the rivals human beings must check in order to make a great success of their own species.

In the previous article on the insects 1ancient lineage, it was stated that in New Zealand a primitive caterpillar, representing a type that seems to have remained unchanged for millions of years, was found feeding on a liverwort, a type of plant that flourished before flowers appeared. A correspondent has pointed out that this discovery was made by the late Mr A'. Philpott, assistant entomologist at the Cawthron Institute. The caterpillar was the young of a Sabatinca moth, the most primitive genus of moths known. In November. 1921, Mr Philpott noted that a species of liverwort was found growing freely at a place where several species of Sabatinca had been taken. Breeding cages were fitted up in order to discover if the species of liverwort had any connection with the life history of Sabatinca. On December 30 a perfect female of the species Sabatinca incongruglla came from one of the cages. A careful search disclosed a cocoon and the cast skin of a chrysalis, from which, doubtless, the perfect moth had emerged.

Mr Hudson states that the fact that this New Zealand insect, Sabatinca incongruella, is the most primitive known member of the Lepidoptera—the moths and butterflies —was announced by Mr E. Meyrick 47 years ago, in collaboration with Mr 11. M’Lachlan, who determined its close connectoin with caddis-flies belonging to the genus Rhyacophila. Mr Meyrick did much to systematise the study of New Zealand’s moths and butterflies, and Mr M'Lachlan, who lived in England, gave all his time and means to natural history, amassing the most' important collection of nerve-wing insects in the Old Country.

Sixty-three years ago Mr W. T. L. Travers, a clever lawyer, a viscous politician, and an able man of science found near an old Maori midden at Lyall Bay, Wellington, a few pebbles with triangular faces, or facets, which seemed to have been produced artificially. Neither he nor Sir James Hector co.uld assign any particular use to the pebbles. The most feasible suggestion was that they had been used to cut, groove, and polish tiki ornaments, but Maoris to whom they were shown said that they had never seen any other stones like them, and that the grooves on a - tiki were not made in that fashion. Finally, Mr Travers concluded that the facets had been made by the wind, using sand as a tool. The work of the wind in polishing, carving, grooving, striating, and wearing the surfaces of rocks had been noted 15 years previously, but Mr Travers apparently wag the first to draw the attention of men of science to this type of wind-worked pebble.

After a few years, his explanation was accepted by geologists. Some of these believe that the facets are caused by sandcarrying winds that blow from one direction or from two opposite directions. Others believe that the work is done by variable winds. Geologists are less interested in the shapes of these pebbles than in their value as indicating past

climatic conditions. Mr W. H. Schoewe, who recently experimented with faceted pebbles at Harvard University, states that the pebbles usually are associated with desert regions, and their presence in ancient rock formations has been interpreted as evidence of arid conditions when the rocks were formed. The pebbles obviously are evidence of intensive action hy the wind, but he explains that they do not necessarily prove arid conditions; if regarded as bearing on the climates of pasf ages, they should be considered with much caution. New Zealand hag a humid climate, and, as Dr A. Cotton has pointed out, no part of it provides examples of the erosive work done by the wind in excavating, carving,, or modifying large topographic forms. Faceted pebbles etched with the use of sand represent the wind’s finer workmanship.