In Touch With Nature

Hawke's Bay Tribune, Volume XVII, Issue 218, 29 August 1927, Page 8

In Touch With Nature

(By

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

THE HAWK-MOTH

FAT mahogany-brown chrysalis x sent by Mr W. S Dempsey. Portland School. North Auckland, if it lived would have developed bv a process of metamorphosis into a handsome moth, with dark greyishbrown fore-wings and vellowish-grey hind-wings, and a body conspicuously and handsomely striped with rosecolour and black. A large curved process, spinning from the head of the chrysalis, represents a prodigious proboscis that would have adorned the creature if it leachc 1 the perfect stage of insecthcod. The caterpillar from which the chrysalis developed was about thre inches long* thicker than a fountain pen and green, with a fine, dark spot on each segment, and on top of its body, near the tail, there was a curved horn which looked quite formidable. The caterpillar was found under kumara plants Kumara leaves sumlied to it were devoured “in a style that might be expected from a caterpillar that size.’’ It was placed in a tin with a supply of earth, into which it burrowed. COMMON IN NORTH ISLAND. . This is the Sphinx moth. Sphinx convolvuli, commonly known as the hawk-moth, almost a cosmopolitan, fairly plentiful in the North island, but rare in the South Isfand. Its vast range is throughout Europe. Asia. Africa, Australia and the South Pacific Islands. It has been found far out at sen In the Sphinx family there are twn types of caterpillars One is bright areen. as described by Mr Dempsev: the other is yellowish-brown. The tail-horn always is present. Usually it is dark red, tipped with white. In both colours, the caterpillars are about three inches long, or more. The Perfect moth has a wing expansion of about three inches and a-half. This is a large size fo New Zaland. but is dwarfed by two Australian members of the family. One has an expansion of six inches, the other of piHit inches. The whole family are known popularly amongst collectors of moths and butterflies as the hawkmoths. New Zealand has tv.o species —Australia has no fewer than fiftvfive. PRETTY TO WATCH. The perfect Sphinx moth in New Zealand emerges from its chrysalis stage in the summer it is described as flying with almost incredible velocity at dusk. Poised in the air above flowers, it/inserts into them its Ion; proboscis and sucks the nectar. Numbers of these moths vary in different years. One summary when they were very plentiful at Ohinemutu. they were seen at dusk c!us r ri;r ’bp evening prim-

roses. “It was a p* watch then *;i • movements as thev darted from flower to flower, never alighting and keping up a constant vibration of their wings as thev probed the yellow blossoms.” a writer who was fascinated bv them wrote. “They seemed to he verv local, as I saw them on only a few grassy slopes near the shore of Lake Rotorua. When, two years fater. 1 visited the same place, at the same season. I saw one* only occasionally, although the evening primroses were in full bloom.’’ SMALLER THAN GHOST MOTH. The Sphinx is not the largest New Zealand moth. It is exceeded in size bv a ghost moth which, until recently, bore the official title Heoialus—Greek for. nightmare This splendid moth, often sent by North Island correspondents, has a wingexpansion in the male of four inches and in the female of five inches and a-half. One of its titles, “virisceris,” refers to the dominant bright green in its wings. Mr G. V. Hudson. whose help is desirable when New Zealand moths and butterflies are considered, evidently has had more opportunities to study the ghost-moth than the hawk-moth. He has found the ghost-moth’s metamorphoses very interesting. The female phses very ineresting. The female Jays a great number of verv small round, yellowish eggs. As she deposits them indiscriminately, the young caterpillars must make their way along the ground to the stems of plants on which thev will feed. Many of them, doubtless, perish on the journey. ITS CATERPILLAR HOME A caterpillar tunnels into the stem of a tree, feedin- on the wood, which it bites off with its strong mandibles. The tunnel always has an outlet, covered with a curtain of silk and refuse, spun level with rhe

surrounding bark, and inconspicuous. Later, the caterpillar makes a much more elaborate home. This is a spacious, irregular, shallow cavity. just under the bark, with a verv large Qpemng to the air. completely covered with a thin silken curtain, almost the same shape and size as numerous marks on many treetrunks INSECTS EXCLUDED. Three large tunnels open into the shallow cavity. The central one is marked by much ingenuity. It goes into the centre of the tree. It seems to terminate suddenly there, but if the floor of the tunnel is examined. close to the point at which it seems to terminate, there is disclosed a round trap-door made compactly of very hard smooth silk. 'Mien the lid is raised, there is a Iresh surprise A perpendicular shaft, half an inch in diameter, from fourteen to sixteen inches long, runs down the tree. The upper end of the shaft is lined with silk. This provides a frame-work on which the trap-door rests when closed. As tho-trap-door is larger than the opening it covers, it is almost impossible to force it open from the outside. The owner, living comfortably inside, has no difficulty in raising the trap-door when it wishes to com e out. Spiders, slugs wood-lice, and insects mav be found in the tunnels, but the trap door stops them from reaching the secluded resting-place. EMERGENCE OF THE MOTH The construction of the trap-ciooi is the caterpillar’s last act berore ii is transformed into a higher creature —a chrysalis. The caterpillar is dull yellow, about tw« inches and a halt long, with a large dark hrown head The chrysalis is pale reddishyellow and attenuated. Ready io enter upon a still higher stage of -ife the chiysalis works its wav up the vertical tunnel bv using booklets, forces open the trapdoor, and wriggles along the horizontal tunnel until it reaches the air. The upper parts of its husk break open. The perfect moth emerges from the chrysalis shell, crawls out. expands its wings and rests on the tree until they are strong enough and bar ’ enough For flight. The story of the ghostmoth’s development from egg to perfect insect is as wonderful and f>s interesting as anything in Nature. HOW TO FIND IT. The present is the best time for obtaining the chrysalis of the nhosti moth. The best way to find it. Mr ; Hudson states, is to pass a straw into a horizontal tunnel on a tree, and move it until i. touches the trap-door. This is announced bv a hollow sound, produced bv the straw striking the lid. which acts like a drum. If there is no sound after the straw is moved about, it is evidence that the insect has left the dwelling or that a caterpillar, not a chrysalis, is inside When a chrysalis is discovered, a section of rhe tree should be cut out and taken home, where the emergence of the perfect insect mav he seen. The ghost-moth appropriately, is nocturnal. and Mr Hudson’s experience is that the perfect insects usually emerge about 5 or 6 p.m. AGE OF THE EARTH. In view o f an article in this column some weeks ago on' the age of the earth, a handsome little cheap edition published by Messrs Harper and Brothers. New lork and London is particularly interesting. Dr. A. Holmes, Professor of Geology at Durham University, in it writes on die age of the earth with scientific precision, and vet with a simplicity that robs the subject of all difficulties to people who wish to penetrate thi§ secret of Nature. Dr. Holmes shows, not only how chapters in the earth’s history have been written, but also how thev mav he read It mav not be easy reading at first, but the story is so fascinating that it is worth while going to some trouble to learn the use of the keys. Dr. Holmes states confidently that the earth’s age l _.it likely to be less than I,6oo.ooo,o<years, vet ; it is still young and vigorous, with a long future of activity in front of it. Further than this: “Beyond the earth, receding into an inconceivable remoteness, lies the stellar universe, the stage in which the drama of our earth is set. The anture and the evolution of the stars and the hidden sources of their blazinn ejjergv are being revealed: we are adventuring towards the verv threshold of Creation. towards the birth-time of the universe itself.” This introducion to geologieaj ideas is one of a ‘‘Things to Know” series.