CICADA CHORUS

Evening Post, Volume CXXVI, Issue 128, 26 November 1938, Page 10

CICADA CHORUS

SIGN OF SUMMER

A NOISY VOCALIST

LONG LIFE UNDERGROUND

"Hark at them locusts!" Made with a fine disregard of grammar and of entomological exactitude, this remark was overheard the other day coming from a workman employed on the new "Evening Post" building in Boulcott Street. "Them locusts" were two cicadas tuning up their strident voices as harbingers of summer, but cicadas are not locusts although they look very much like them. Incidentally, at the moment of the remark quoted above, "them locusts" were making their notes heard above the ear-split-ting din of a pneumatic drill, and it is a fact that cicadas, so penetrating are their voices, can be heard a quarter of a mile away.

These interesting insects make them* selves heard with unfailing regularity every summer, although it is naturally out in the country and not in the cities^ that they are heard in greatest numbers. It seems to take them a little time to get really tuned up to concert pitch: at the beginning of the summer they are a bit hesitant about giving full rein to their vocal powers, but they get warmed up, so to speak, as the weather gets hotter, and day after day and hour after hour (often well into the night) they screech their love songs. At least it is supposed to be a kind of love song. Only the males of the species give voice to it, all lady cicadas being dumb and doing all the listening—quite unlike their human counterpart. But it is a debatable point as to whether the lady cicada listens in the ordinary sense of the word, for search as he may with a microscope the entomologist can find I not the slightest trace of any sort of auditory organ. But it can hardly be imagined that the vocal efforts of the wooing male are entirely wasted. Although without ears, Mrs. Cicada no doubt has some means of appreciating the vibrations set up by the male's screeching.

There is a popular belief, without any foundation in fact, that the cicada makes its distinctive noise by rubbing its barbed legs over the hinder part of its body, using them like a bow on a violin. This, however, is not the case. The cicada's sound-producing apparatus is complex and peculiar. Tucked away in the underpart of its anatomy it has a kind of drum with several tightly-stretched membranes. These are vibrated by muscular movement, and the sound can be modified by the bringing into action of what may be likened to sounding boards.

The cicada is an interesting insect, and fossil remains indicate that they have hardly altered in the course of evolution during the last few million years. They are found in many parts of the world, but are more numerous in the Tropics than elsewhere. New Zealand possesses several species, the largest having a wingspread of about 3&in and being a pretty olive-green insect with black markings. This one has what may be described as a loud chirp, and it punctuates its serenade with clicks of the wings. INTERESTING LIFE CYCLE. The life history of the cicada follows a distinctive routine. The nymphs live underground around tree . roots, upon the sap of which they live. This subterranean existence may last for several years. In one American species it lasts for as long as 17 years, hence the "17-year locust" which, periodically makes itself a nuisance . in the United States. Most species, however, spend only from three to six years underground before becoming complete insects. When the time of the subterranean sojourn is nearly up, instinct causes the nymph to burrow towards the surface of the ground. When the right climatic conditions are present it emerges from its tunnel, looking rather like a strange gnome from the underworld. This thing, with a hunched back and large forequarters, climbs a few feet up a tree. There it pauses and moults, and there emerges the perfect insect. The clothes which have been shed are very noticeable in the early summer months. Having unfolded itself, spread out its legs, and unrolled its wings, the cicada is ready for a brief life and a gay one. It has a strong beak and sharp claws. With the latter it clings to trees and shrubs, and with the former it sucks the sap from the branches. This sucking is capable of doing considerable damage to vegetation, but perhaps even more is done when the time comes for the lady cicada to get busy on the egglaying job. For this purpose she deftly slits the bark, and the eggs are placed beneath it. When the baby cicadas hatch out from the eggs which have survived being made into breakfast dishes for birds, they resemble large fleas, only they don't hop. The first thing the babies do is to scramble down the tree trunk towards the ground, their one desire apparently being to get safely into the protecting earth, and once their objective is gained there they stay until the cycle outlined above starts again. AN EXPERIMENT TO TRY. "Them locusts" are therefore insects of more than passing interest. And there is an experiment which, can be tried on them by those of an inquiring turn of mind. It has to do with the cicada's sensitivity to vibrations (although those which gave rise to the remark quoted at the beginning of this article did not seem at all sensitive to the very marked vibration of the penumatic drill). One writer states that if one goes into the bush or to any place where cicadas abound and are singing and claps one's hands vigorously, they will at once cease their orchestral accompaniment. Furthermore, so it is asserted, they will come and settle on the person who has started the new vibration by clapping. Whether the playing of bagpipes would have the sarr^ effect, this writer does not say. The clapping experiment, however, is one which anyone could try, but no prize is offered to the clapper getting most settlers. However many cicadas may respond to the clapping invitation, there is no need to be alarmed. They won't bite, even if they will tickle.