Evening Republican, Volume 19, Number 24, Rensselaer, Jasper County, 28 January 1915 — INSECT MUSICIANS AND THEIR AUDIENCES [ARTICLE+ILLUSTRATION]

INSECT MUSICIANS AND THEIR AUDIENCES

tws NSECTS are a silent people ■ in the main. Many of them AtM pass through life without uttering a single sound But there are some interesting exceptions to this rule. yV'k' The harvest flies, or cicala*' das, for example, are notoriously noisy, the “sons” of some species having been compared to the shrill whistle of a locomotive engine. They are very abundant in the warmer regions of both hemispheres. The males alone are tuneful —a fact which was commented upon by certain of the Greek poets and philosophers, one of whom writes: “Happy the cicadas live, since they all have voiceless wives.” Strictly speaking, however, the cicada is not a vocalist, but an instru-

mentalist The sounds that it makes are due to a special_ mechanism which resembles a* pair of kettledrums. These have their place in cavities on each side of the thorax, and are protected beneath by large plates which may possibly act also as sounding boards. The membranes of the drums are not beaten, but are thrown into rapid vibration by a special set of voluntary muscles, the result being the

loud, shrill music for which the cicada is famous. Apart from the cicadas, the only other notably sonorific insects are fouqd in the group which naturalists term the “leaping orthoptera”—i. e. the grasshoppers, crickets and their allies. In these instances the analogy of the drum must be discarded for that of the fiddle. L<et us take "first the grasshoppers. Everyone has listened to their chirping, and perhaps some inquiring spirits have observed that the sound is always accompanied by a kind of swaying of the insect’s body, and an alternate movement of its hindlegs. But the full inwardness of the matter can only be appreciated by the aid of the microscope. On a certain ridge on the inner side of the grasshopper's hind femur—.the thigh of the great leaping leg—there is a row of extremely modified hairs. This ridge represents the bow of the soundproducing apparatus. By the movement of the leg it is rubbed to and fro against a prominent nervure or “vein" of the closed fore-wing; and this fiddling process gives rise to the. grasshopper’s well-known "song.” “Stridulation.” Naturalists call the method "stridulation." In the case of the crickets it is managed in a different way, viz. by rubbing one wing over the other. Each fore-wing of the male is furnished with a vein which is minutely ridged or filelike on its under side; and this bow plays upon a vein on the upper surface of the wing beneath it. As the apparatus is in duplicate—each wing having its vein and bow — the insect is ambidextrous, so to speak. In practice, however, it is found that the right wing is generally, though not always, uppermost. The reverse is true of the long-horn, treefrequenting grasshoppers. Their solitary filelike bow is found on the underside of the left fore-wing, which is always uppermost. In these insects —and in the crickets to a lesser extent —the overlapping fore-wings form a kind of resounding chamber which intensifies the volume Of each note that the fiddler produces. Time and Temperament.

Dr. S. H. Scudder, an eminent observer of insect life in America, has expressed some of the songs of crickets and grasshoppers in musical notation. He has also recorded the curious tact that there is a distinct relation between the rapidity of note production and the temperature. On ■warm days, when the sun is shining brightly, these little musicians fiddle away with all their might, whereas in dull and chilly weather their execution is slow and mournful. Many crickets, however, remain, silent until the shades of evening begin to fall, and then begin loudly to serenade their lady-loves. For this is really the outcome of the whole matter. Only in rare instances do female insects possess the gift of melodious expression. As with the singing of birds, so with the drumming and fiddling of insects, each is essentially the , language of courtship. Loye makes the world go round! Crickets have been observed to listen eagerly—one might say, critically—to the performances of their wooers, as if anxious to get the full

benefit of every note produced. But how does an insect “listen?” In most insects the auditory organs if they can be demonstrated at all, take the form of excessively minute structures connected with nerves. These structures, which are microscopic hairs, and cavities, are found most commonly upon antennae, but they may also occur upon other parts of the body. So far as the writer is aware, the cicadas have not been shown to possess any specialized “ears.” We are thus left to assume that they gain their- impressions of sound by means of scattered sense organs such as those which have just been mentioned. Indeed, some authorities are of opinion that cicadas do not hear at all in our sense of the word, but that they “feel" rhythmical vibrations. Insects With Ears. With grasshoppers and crickets, however, the case is quite different. These insects undoubtedly possess

ears—elaborate structures admirably adapted to receive and transmit pound waves. But the external openings of these organs are most surprisingly located. In crickets and long-horn grasshoppers there are two curved slits In the tibia or shin of the foreleg, one on each side, just below the “knee.” These are the openings of the ears! Each slit gives access to a tympanum, or “drum,” which is connected with air spaces and nerve endings. In the case of the short-horn grasshoppers, the ears occupy an equally unexpected position, viz. at the base of the abdomen. The opening on either side may be found beneath the wings, just above the attachment of the great hind-leg. It will be well, in conclusion, to emphasize the fact that the noises made by insects are strictly instrumental. No insect has a “voice” —that' is, the power of producing sounds by the expulsion of air from the lungs through the throat and mouth. Indeed, insects have no lungs, nor do they use their mouths for breathing. On the contrary, they take in atmospheric air through a number of small openings along the sides of the body. These openings are called "spiracles.” They give access to an elaborate system of minute pipes, or "tracheae,” which ramify among the insect’s living tisi sues and convey to them the oxygen necessary for the discharge of the various vital processes. Just within each spiracle there is an ingenious little valve which is opened and closed by a muscular contraction. The circulation of air, to and fro through the spiracles, is kept up by a constant palpitating movement of the whole abdomen. This may be seen, for example In a wasp that is regaling itself in the dish of fruit on our table; but In the case of a hibernating queen wasp, the body Is practically motionless—the reason being that the insect’s dor mancy is so complete that It requires scarcely any oxygen to continue In being. The nearest approach to a true "voice” among Insects is the humming sound produced by a mechanism within the spiracles. If we shut up a bee in a box, we shall find that it is able to hum loudly, even though it may be unable to agitate its wings. The mechanism is too complicated to describe here; but it may be roughly likened to a wind Instrument, Buch as a cornet.