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2 corrections, most recently by tobyyy - Show corrections

THE CICADA.

(Written for the "Town and Country 'Journal.")

(UV HOWARD ASHTON.)

Summer has come headlong upon us, and In the forehead of summer HveB the cicada, whose song makes the warm dusk seem still warmer. A beautiful and interesting insect, this,-digni fied by name in scng and story as far' back as Anacreon, who likens him to a king In that he ls happy, and lives upon dew. Whether kings are happy ls a moot point, but none that I can recall have lived upon dew, any more v..an does the cicada. These poets are so Inaccurate. Our cicada ls quite erroneously styled a "locust." For he belongs to the same order as the aphis and frog-hopper, while tho true locust is a relative of the grasshopper and cricket. And, unlike the locust, he does little damage.

It is doubtful whether one Australian In a thousand has failed to notice the cicada's song. It is equally doubtful whether one Aus tralian in a thousand knows how that song ls produced. . The general opinion suspects an air instrument. But if one considers that all stridulating Insects produce their sound by me chanical means, usually friction of a ridged sur face over a hard plate; If, moreover, one con siders the size of the common green cicada (Cyclochila australáüiae), ono muBt como to the conclusion that in such a small body the pro duction, of a current of air sufficient for a sound which ls audible at half a mile ls very unlikely, indeed.. The sound itself ls a lure, a signal to the female. Only the male sings, though, the female possesses, the rudiments of sound organs, It is produced by the rapid ac tion of powerful abdominal muscles* upon a curiously constructed membrane. So far as I know, a popular description of this membrane and muscle has not been so far essayed.

The following description is the result of some dissections I made last year. The subject was, Altria perulata (Figure 1), commonly known as the Floury Baker, on account of the two white sacks (b b) and the powdering of white under the abdomen. Inside these structures, which

The Cicada (Altria Perulata).

are apparently sounding-boxes, are placed the drums. These consist of membranous discs, concave outward from the insect's body, and supported by a strong framework upon the first abdominal segment. They are built in over lapping ridges, which gives them greater strength and resiliency. One of them is shown In Figure 2; (a) is a section of the membrane, lt attaches to the muscle (c) by means of the tendon (b), and the convexity is plainly shown

outwards into the resonator (d). It will be noticed that the attachment of the tendon is at some distance from the contre of the drum.

If ene takes a broken celluloid ball, and ce ments a strip of linen on the concave side, well awáy from the centre, a model is formed of the tympanum of the cicadn. If the linen be pulled, the dome of the arch will give way with a snap; as the linen is released it will spring back into position with another snap. But if the linen be glued directly to the centre, although it will give way and spring back, there will be no sound, for upon the free play of the centre de pends the vibration which is responsible for that sound. ThlB, thon, explains tho uncentral attachment of the cicada's tendon. It must be understood that the note of the cicada does not depend at all upon the frequency of the con traction and relaxation of the muscle controll ing tho tendon. Ono contraction gives the same note as 100. But the rapid reactions of the muscio give the continuity of the song. Indeed, it seems possible that euch libre of tho muscle works independently of the rest, the con traction and relnxntion being thus carried along at a hugo rate from fibre to fibre.

So much for the production of tho sound. But that is by no means all that Nature has done for this favoured Insect. While many species depend upon the unaided sound of these organs, a few have special contrivances for augmenting and increasing the noise. Tho species illus trated hns such an arrangement in the white bags abovement ioned. Several have hollow abdomens. I have one from Oeylon which has such a hollow abdomen, swollen out greatly be yond the limits of ordinary species, and in deed beyond that of the fomalo of its own kind. And a Northern River species (Cystosomn) has Its belly distended into a monstrous bladder of air. Some of the true locusts and grasshoppers also rejoice in similar sounding boxes.

Thoro is another point of mechanical interest In tho structure of tho cicada. The nervure, or vein, marked a in Figure 1, the last ono on tho fore-wing, engages by means of a hook with the first vein of the hind wing. The Insect can unhook or hook these nervures at will, thus converting himself from practically a four winged into a two-winged creature. In thlB respect ho ls similar to the wasp, as also In tho matter of the three ocelli, or little eyes, upon his forehead. Another thing which may not bo popularly known Is that, tn tho same Bi'OcloB, the veins of tho wing uro idontlcal In number nnd place; and that oven in dlfforont Bpuolos and genera from wldoly different coun tries the popular eye can discover very little difference In this rospect. So similar are they

timi a certain interruption on tho norvuro, murker! c in Figure 1, occurs in overy spoclot which I have so far examined. This slmllnritj of struciuro points inovltably to a common ori gin, and adds ono more confirmation to the thcorj of Charles Darwin.

In tho family of Cieadidae this country ls In deed rich. I certainly do not overstate the cas», ii. saying that In New South Wales there aro at least IOU well-marked and distinct species. The largost in my collection ls Thopha saccata; measuring 5%ln from wing-tip to wing-tip. The smallest measures IViln, a species living on the coast, and classified by Mr. Froggatt as Pauro psaltn annulatn. This little thing is not larger in body than a blowfly, but ho makes a deal of noise withal. He is the first cicada to emerge from tho ground this year, and last year he was the last lo Btirvive In the frosty grip of advanc ing winter. He who desires to catch this one must have patience, and sharp sight.

In. conclusion, the cicada, unlike the butter fly, ha3 but two stages of existence. The but terfly logins SB a grub, passes into a more or less inert chrysalis, and from thence emerges into the thing of beauty which flaunts Its bril liance among the trees. The cicada, on its emorglni; from the egg, laid in the bark of the trees by a careful mamma, crawls down Into tho ground. He is In the same shape as that from which he later emerges, but of course much smaller. He looks rather like a little lobster,' his wings, of course, are curled up in this pupa-case until such time as, after succes sive castings of his tight skin as he grows, he ls ready to cast the last one upon the tree trunk. Then his wings unfold, and he is ready for Nature's great business of reproduction, filled with fine wings, and a loud voice. The common green cicada is underground for, in all probability, three years. But this record ls broken by an American species (C. septemde cim), whose pilgrimage from egg to winged per/ection lasts the astounding period of 17 years. Specimens of Cyclochlla, which I have kept in confinement on living trees and shrubs, have survived from two to three weeks. Of cc ni se, under free conditions, they may sur vive longer, but I think that three weeks is about their period. Three years as gnomes, and three weeks as vocalists, and then death. The wasps and sparrows are their chief ene

THE SOUNDING DRUM.

mles;' and the small boy. with the-.gaping trousers pocket, and the hot, moist hand.

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