IN TOUCH WITH NATURE

Hokitika Guardian, 9 April 1931, Page 2

IN TOUCH WITH NATURE

EARLIEST FLYERS IN THE (By J. Drummond, F.L.S., F.Z.S.) Often seen hovering over flowers ana slipping nectar with its long proboscis. tho hawk-moth is one ot tho handsomest and most elegant insects in New Zealand. It probably cannot be seen anywhere at present, but vn November, December, and January visiting flowers as stated, or flying in the evening twilight with surprising swiftness, it is fairly plentiful in the northern parts Os the North island, rarer south of NapTer and New Plymouth, and seen only occasionally in and near Christchurch, Blenheim, Nelson and Hokitika. Its somewhat stout body and its rapid evening flight distinguish it at a short distance. Closer it is easily recognised by its light grey body ami black, white and rose-colour-ed stripes on the sides, HAWK-MOTHS TAKE THE PRIZE. Trials in Germany show that members of the hawk-moth’s family are the swiftest flyers amongst insects. The test was made in n room lighted by cum window, The time taken In flying direct from the dark side of the room to the. light was recorded. Hawkmoths flew nit ft speed of fifteen metres about 49ft, a second. A horse-fly came second with about 45ft Gin a second A dragon-fly was third, with 32ft Gin. A house-fly’s speed was Oft Gin., a humble bee’s about 16ft. CAN GO SIDEWAYS. Insects as a class have practised tho art of flying for several hundred million years, according to the way in which paleontologists read th e records in the rocks, and it is not surprising that they ar 0 experts in the art. .At the same time, it is pointed out that there is ample room to marvel at tlieir “stunts” in the air. In addition to steering m forward flight, many of them can go into reverse gear and fly directly backward without altering the position of their bodies. Mori, amazing is the fact that, by using a mechanism of adjustment, they can flv sideways, right or left, at right angles to the bodv t Drone-fliers which in almost all parts of New Zealand often are seen in tho summer hovering over dandelion flowers, and which in appearance mimic bees, have this faculty. It is pos. T L Lv.o:on-flies,

ordinary flies and bia • ''“L'' watch these insects on tim wr are surprised to see them suddeni dart to one side, or go backward, tho head still pointing in the direction of the arrested forward flight, NO STEERING GEAR. Mere ability to pass through the air is pot regarded as efficient flight. Real flight is defined as involving the ability to steer a definite course and to turn in any direction desired. By this test some of the smaller grasshoppers are not experts, although they sustain themselves in the air by using their wings; but most insects that have flight are exports. A hawk-moth poised in the air, extracting nectar from a flower, is held up as the best example of the skill with which insects can use their wings to control their flight. STEER BY WINGS. Insects have no rudders. Experiments failed to prove that they use their bodies or their legs to direct or alter their course in the air. Shadowgraphs of flying insects record no alter ation in the position of the body or of the legs during a change in the direction of the flight. Living insects were impaled on slender pins. Insects in this position vibrate their wings in the same way as in flight, and revolve to the right or left of the pin. In the experiment, the turning movement was never accompanied by movements of the body or of tho legs.

Steering evidently depends on the action of the wings. Mr R. E. Snodgrass, a member of the United States Bureau off Entomology, who has made the flight of insects a study, believes from the evidence, tha a flying insect controls the direction of its flight like a rower in a boat, who, in the absence of a steerer, keeps to his course or alters it by changes in the handling of the oars. OLD-TIME INSECTS. There are wingless insects even now but only winged forms of insects have been preserved as fossils .The geological period at which insects first appear ed is unknown. Their lossil record, in New Zealand is almost a complete blank. In other countries, their ear.ves fossil remains have been found in rocks of the Carboniferous Period, which, according to modern methods of calculating geological time, 'Were laid down some 800.000,000 years ago. There is no evidence that mammals, birds or flowering plants existed then, although there were amphibians ana reptiles of a sort. HAVE CHANGED LITTLE. The dismal swamp-lurests of the Carboniferous Period weiv iavour.ible to the development of insects. The Carboniferous lias been called the Ago J

of Giant Insects. They existed there in great numbers. The strangest tiling about those old-time insects is that they differed comparatively little lro.ni modern insects. All the Carbonilerous insects discovered up to the presenttime had two pairs of wings, well developed. The structure of their wings is so much alike the wings of our own insects that only a specialist can detect the differences. The oldest species

of insects known, like present insects had a head, thorax, an abdomen and six logs fixed to the thorax. Jnvesti. gations have shown that, in bodily (form and structure, there is nothing to distinguish a Carboniferous insect from one of its modern descendants. The conclusion is that the Carboniferous inserts develop from wingless insects; but the evolution must have gone on for millions of years before the Carboniferous Period. The origin of insects’ wings is a mystery.