The Grasshoppers Cousins

Nature's tendency s to produce groups rather than individuals Any animal you can think of resembles in some way another animal or a number of other animals. An insect resembles on the one hand a shrimp or a crab, and on the other a centipede or a spider. Resemblances among animals are either superficial or fundamental. For example, a whale or a porpoise resembles a fish and lives the life of a fish, but has the skeleton and other organs of land-inhabiting mammals. Therefore, notwithstanding their form and aquatic habits, whales and porpoises are classed as mammals and not as fishes.

When resemblances between animals are cf a fundamental nature, we believe (hat they represent actual blood relationships carried down from some far distant common ancestor; but the determination of relationships between animals is not always an easy matter, because it is often difficult to know what are fundamental characters and what are superficial ones. It is a part of the work of zoologists, however, to investigate closely the structure of all animals and to establish their true relationships The ideas of relationship which ("he zoologist deduces from his studies of the structure of an.mals are expressed in his classification of them. The primary divisions of the Animal Kingdom, wh.ch is generally likened to a tree, are called branches, or phyla (singular, phylum).

The msects, the centipedes, the spiders, and the shrimps, crayfish, lobsters, crabs, and other such creatures belong to the phylum Arthofoda- The name of this phylum means

THE GRASSHOPPER'S COUSINS

"joinled-legs"; but, since many other animals have jointed legs, the name is not distinctive, except in that the legs of the arthropods are particularly jointed, each being composed of a series of pieces that bend upon each other in different directions. A name, however, as everybody knows, does not have to mean anything, for Mr Smith lût 14. Examples of fcur common classes of the Arthropoda ■\(a crab (Crustacea) B, a spider (Arachmda). C, a centipede (Chilopoda) d, a fly (Insecta or Hexapoda)

may be a carpenter, and Mr. Carpenter a smith, A phylum is divided into classes, a class into orders, an order into jamities, a family into genera fcingular, genm). and a genus is composed of species 'the singular of which is also species). Species are hard to define, but they are. what we ordinarily regard as the individual kinds of animals Species are given double names, first the genus name, and second a specific name For example, species of a common grasshopper genus named Melanoplus are distinguished as Melanoplus atlanus, Melanoplus j'emur-rubrum, Melanoplus dijjerentiahs, etc.

lût 14. Examples of fcur common classes of the Arthropoda ■\(a crab (Crustacea) B, a spider (Arachmda). C, a centipede (Chilopoda) d, a fly (Insecta or Hexapoda)

The msects belong to the class of theArthropoda known as the Insect a, or Hexzpoda. The word insect, as we have seen, means "m-cut," while hcxapod'" means ' six-legged '--either term, then, doing very well for insects. The centipedes (Fig 14C) are the Myriipoda, or many-footed arthropods; the crabs (A), shrimps, lobsters, and others of their kind are the Crustacea, so called because most of them have hard shells; the spiaers (B) are the Arachnida, named after that ancient Greek maiden so boastful of her spinning that Minerva turned her into a spider; but some arachnids, such as the scorpion, do not make webs

The principal groups of nsects are the orders. The grasshopper ana its relatives constitute an order; the beetles are an order; the moths and butterflies are another order; the flies another; the wasps, bees, and ants still another. The grasshopper's order is called the Orthopte^a, the word meaning ' straight-wings, but, again, not significant in all cases, though serving very well as a name The order is a group of related famdiss, and, in the Or thoptera, the grasshoppers, or locusts, make one family, the. katydids another, the crickets a third:; and all these in sects, together with some others less familiar, may be said to be the grasshopper's cousins.

The orthopteran families are notable in many ways, some for the great she attained by their members, some for their remarkable forms, and some for musical talent While this chapter will be devoted principally to the cousins of »-he grasshopper, a few things of interest may still be sud about the grasshopper himself, in addition to what was given in the preceding chapter.

The Grasshopper Family

The family of the grasshoppers, or locusts, is the Acndidae All the members are much alike in form and habits, the agh some have long wings and some short wings, and some reach the enormous size of nearly six inches in plate 1

plate 1

Forest Insects List Ppt

A group of insects representing five common entomological Orders. Figure 1 is a damselfly, a kind of dragonfly, from INew Guinea, Order Odonata; 4 is a grasshopper, and 6 a winged walking-stick of Japan, representing two families of Orfhoptera; I and 8 are sucking bugs, Order Hem ptera, which includes also the aphic's and the cicadas; 3 is a wat,p from Paraguay, and 7 a solitary bee from Chile, Order Hjmenoptera; 5 is a two-winged fly of the Order Diptera, from Japan. To entomologists these insects are known as follows: 1, Paryphes laetus; 1, unidentified, 3, Pepsis com-pleta; 4, Heliastus benjamini; 5, P'antophthalmus vittatus; 6, Micadina ■phluctanoides; 7, Caupolicana fulvicolHs; 8, Margasus qfzeli

THE GRASSHOPPER'S COUSINS

length The front w.ngs are long and narrow (Fig. 63, PV2), somewhat stiff, and of a leathery texture They are k.id ov^er the thinner hind wings as a protection to the latter when the wings are folded over the back, and for this reason they are called the tegmina (singular, legmen). The hind Wings, when spread {Wsfa are seen to be large fans, each with many ribs, or veins, springing from the base These wings are gliders rather than organs of flight. For most grasshoppers leap mto the air by means of their strong hind legs and then sail off on the outspread wings as far as a weak fluttering of the latter will carry them. One of our common species, however, the Carolina locust (Frontispiece), is a strong flyer, and when

Fig. 15. A grasshopper, Chloetuns conspersa, that makes a sound by scraping its. hind thighs over sharp-edged ve ns of its wings A, the male grasshopper, show ng the sound making veins of the w.ng (¿) B, nner surface of right hmd leg, showing row of teeth (a) on the femur. C, several teeth of the femur (enlarged)

flushed flits away on an undulating course over the weeds and bushes and sometimes over che tops of small trees, but always swerving this way and that as if unde cided where to alight The great flights of the migratory locusts, described in the last chapter, are said to have been accomplished more by the winds than by the insects' Strength of wing.

The locusts are distinguished by the possession of large

Fig. 15. A grasshopper, Chloetuns conspersa, that makes a sound by scraping its. hind thighs over sharp-edged ve ns of its wings A, the male grasshopper, show ng the sound making veins of the w.ng (¿) B, nner surface of right hmd leg, showing row of teeth (a) on the femur. C, several teeth of the femur (enlarged)

organs on the sides of the bodv that appear to be designed for purposes of hearing. No insect, of course, has ears on its head; the grasshopper's supposed hearing organs are located on the base of the abdomen, one on each side (Fig. 63, Tm). Each consists of an oval depression of the body wall wich a thin eardrumlilce membrane, or tympanum, stretched over t. Air sacs lie against the inner face of tne membrane, furnishing the equilibrium of air pressure necessary for free vibration in response to sound waves, and a complicated sensory apparatus is attached to its mner wall Even with such large ears, however, attempts at making the grasshopper hear are never very successful; but its tympanal organs have the same structure as those of :nsects noted for their singing, which piesumably, therefore, can hear the ir own sound productions

Not many of the grasshoppers arr. muscial. They are mostly sedate creatures that conceal their sentiments, f they have any They are awake in the daytime and they sleep at nigh, commendable traits, but habits that seldom beget much 111 the way of arti tic attainment Yet a few of the grasshoppers make sounds that are perhaps music in their own ears One such is an unpretentious little brown species (Fig. 15) about seven eighths of an nch in length, marked by a large black spot on each side of the saddlelike shield that covers his back between the head and the wmgs. He has no other name than his scientific one of Chioealti s compere a, for he is not Widely known, since his music is of a very feeble sort. According to Scudder. his only notes resemble tetkk-tsikk-tsikk, repeated ten or twelve times m about three seconds in the sun, but at a slightly lower rate in the shade. Chlcealtis is a fiddler and plays two instruments at once. The fiddles are his front wmgs, and the bows his fund legs. On the mner surface of each h>nd thigh, or femur, there is a row of minute teeth (Fig 15 B, a), shown more magnified at C. When the thighs are rubbed over thi edges of the wings, their teeth scrape on a sharp-edged vein indicated by b. This pioduces the

/¿/¿¿-sound just mentnned. Such notes contain little music to us, but Scudder says he has seen three males sing mg to one female at the same cime This female however,

Fig 16 A grasshopper, Mecostelhus gracilis, that makes a sound by sere,ping sharp ridger on the inner surfaces of its hind thyhs over toothed vei ns of the waigs A, the male grasshopper. B, left front wing; the rasping vein is the one marked I C, a part of the rasp.ng vein and its branches more enlarged, showing rows of teeth

Fig 16 A grasshopper, Mecostelhus gracilis, that makes a sound by sere,ping sharp ridger on the inner surfaces of its hind thyhs over toothed vei ns of the waigs A, the male grasshopper. B, left front wing; the rasping vein is the one marked I C, a part of the rasp.ng vein and its branches more enlarged, showing rows of teeth was busy laying her eggs in a near-by stump, and there is no evidence gi/en to show that even she appreciated the efforts of her serenadars.

Several other little grasshoppers fiddle after the manner of Chloealtis; but another, Mecoste.thus gracilis by name (F:g. 16), instead of having the rasping points on the legs, has on each fore wing one vem (B, I) and its branches provided with many small teeth, shown enlarged at C, upon which it scrapes a sharp ridge situated on the inner surface of the hind thigh

In another group of grasshoppers there are certain species that make a noise as they fly, a crackling sound apparently produced in some way by the wings themselves. One of these, common through the Northern States, is known as the cracker locust, Circotettix verruculatus, on account of the loud snapping notes it emits. Several other members of the same genus are also cracklers, the noisiest being a western species called C. cariingiznus. Scudder says he has had his attention dra wn to this grass hopper " by its obstreperous crackle more than a quarter of a mile away In the arid parts of the West it has a great fondness for rocky hillsides and the hot vicimty of abrupt cliffs in the full exposure to the sun, where 'ts clattei ng rattle re-echoes from the walk "

The Katydid Family

While the grasshopper? give examples of the more pnmitive attempts of insects at musical producticn and may be compared in this respect to the more primitive of human races, the katydids show the highest development of the art attained by insects. But, just as the accomplishments of one member of a human family may give prestige to all his relations and descendants, so the talent of one noted member of the katydid family has given notoriety to all his congeners, and his justly deserved name has come to be applied by the undiscnminating public to a whole tribe of smgers of lesser or very mediocre talent whose only claim to the name, of katydid is that of family relationship. In Europe the katydids are called simply the longhcrn grasshoppers. In entomology the family is now the Tettigonndae. though it had long been known as the Locus tidae

The katydids in general are most easily distinguished from the locusts, or shorthorn grasshoppers, by the great length of their antennae, those delicate, sensitive, tapering threads projecting from the forehead. But the two families differ also .n the number of joints .n their feet, the grasshoppers having three (Fig. 17 A) and the katydids four (B). The giasshoppers place the en the foot on the ground, while the katydids ordinarily walk on the three basal segments only, carrying the long terminal joint elevated. The basal segments have pads on their undei sides that adhere to any smooth surface such as that of a leaf, but the terr :nal joint bears a pair ol claws used when it is necessary to grasp the edge of a support. The katydids are mostly creatures of the night and, though usually plain green in color, many of them have elegant forms Their attitudes and general comportment suggest much more refinement and a higher breeding than that of the heavy bodied locusts. Though some members of the katydid family live in the fields and are very grasshopperilke or even cricketlike in form and manners, the characteristic species are seclus;ve nhabitants of shrubbery or trees These are the true aristocrats of the Orthoptera

An insect musician differs in many respects from a human musician, aside from that of being an insect instead of a human being. The insect artists are all instrumentalists; but since the poets and other ignorant people always speak of the "singing of the crickets and katydids, it will be easier to use the language of the public than to correct it, especially since we have nothing better to offer than the word stridulating, a Latin derivative meaning to creak But words do not matter if we explain what we mean by them. It must be understood, therefore, that though we speak of the "songs" of insects, insects do not have true voices in the sense that 'voice" is the production of sound by the breath playing on vocal cords. All the musical instruments of insects, it is true, are parts of their bodies; but they are to be likened to fiddles or drums, since, for the

Fio. 17. Distinct!vt characters in the feet of the three families of singing

Orthoptera A, hind foot of a grass hopper B, hind foot of a katydid. C, hmd foot of a cricket

Fio. 17. Distinct!vt characters in the feet of the three families of singing

Orthoptera A, hind foot of a grass hopper B, hind foot of a katydid. C, hmd foot of a cricket production of sound, they depend upon rasping and vibrating surfaces. The rasping surfaces are usually, as in the instruments of the grasshoppers (Figs. 15, 16), parts of the legs and the wings. The sound may be intensified, as in the body of a stringed instrument, by special resonating areas, sometimes on the wings, sometimes on the body. The cicadas, a group of musical insects to be described in a special chapter, have large drumheads in the wall of the body with which they produce their shrill music. They do not beat these drums, but cause them to vibrate by muscles in the body. The musical members of the insect families are in nearly all cases the males, and it is usually supposed that they give their concerts for the purpose of engaging the females, but that this is so in all cases we can not be certain.

The musical instruments of the katydids are quite different from those of the grasshoppers, being situated on the over

Hic. 18. The front wings, or tegmina, of a meadow grasshopper, Orchelimum lalicauda, illustrating the sound-making organs typical of the katydid family

A, left front wing and basal part of right wing of male, showing the four main veins: subcosta (Sc), radius (R), media (Ai), and cubitus (Ca); also the enlarged basal vibrating area, or tympanum (Tm), of each wing, the thick file vein (/r) on the left, and the scraper (j) on the right

B, lower surface of base of left wing of male, showing the file {/) on under side of the file vein (A,fo)

C, right front wing of female, which has no sound-making organs, showing simple normal venation lapping bases of the front wings, or tegmina. On this account the front wings of the males are always different from those of the females, the latter retaining the usual or primitive structure. The right wing of a female in one of the more grasshopperlike species, Orchelimum laticauda (Fig. 30), is shown at C of Figure 18. The wing is traversed by four principal veins springing from the base. The one nearest the inner edge is called the cubitus (Cu) and the space between it and this margin of the wing is filled with a network of small veins having no particular arrangement. In the wings of the male, however, shown at A of the same figure, this inner basal field is much enlarged and consists of a thin, crisp membrane (Tm), braced by a number of veins branching from the cubitus (Cu). One of these (fv), running crosswise through the membrane, is very thick on the left wing, and when the wing is turned over (B) it is seen to have a close series of small cross-ridges on its under surface which convert it into a veritable file . On the right wing this same vein is much more slender and its file is very weak, but on the basal angle of this wing there is a stiff ridge (¿) not developed on the other. The katydids always fold the

Katydids With Tympanu

Fig 19 Wings, sound-making organs, and the "ears" of a conehead grasshopper, Neoconocsphalus ensiger, a member of the katydid family A, B, right and left wings, showing the scraper (s) on the right, and the file vein \/v) on the left. C, under surface of the file vein, showing the file (/). D, front leg, showing slits (e) on the tibia opening into pockets containing the hearing organs (fig. 20 A)

Fig 19 Wings, sound-making organs, and the "ears" of a conehead grasshopper, Neoconocsphalus ensiger, a member of the katydid family A, B, right and left wings, showing the scraper (s) on the right, and the file vein \/v) on the left. C, under surface of the file vein, showing the file (/). D, front leg, showing slits (e) on the tibia opening into pockets containing the hearing organs (fig. 20 A)

v-ings with the left overlapping the right, and in this position the file of the former lies above the ridge (s) of the latter. If now the wings are moved sidewise, the file gracing on the ri dge or scraper causes a rasping sound., and this is the way the katydid makes the notes of its music, ^he tone and volume of the sound, however, are probably m large part produced by the vibration of the thin basal membranes of the wmgs, which are called the tympana (Tm).

The instruments of different players differ somewhat in the details of their structure. There are variations in the form and size of the file and the scraper on the w: ngs of different species, and differences in the veins supporting the tympanal areas, as shown in the drawings of these parts from a conehead (Fig 27) gi ven at A, 8. and C, of Figure 19. In the true katydid, the greatest singer of the family, the file, the scraper, the tympana, and the wmgs themselves (Fig. 26) are all very highly developed to foim an instrument of great efficiency. But, 111 general, the instruments of different species do not differ nearly so much as do the notes produced from them by their owners An endless number of tunes may be played upon the same fiddle With the insects each musician knows only one tune, or a few simple variations of it, and this he ha.s inherited from his ancestors along 'with a knowledge of how to play it on his inher ted instrument. The stridulatmg organs are not functionally developed until maturity, and then the insect forthwith plays hi? native air. He. never disturbs the neighbors with doleful notes while learning.

;ry curiously, none of the katy dids nor any member of their family ha > the earhke crgans on the sides of the body possessed by the locusts. Wrhat are commonly supposed to be their organs of hearing are. located in their front legs, as are the similar organs of the crickets. Two vertical slits on the upper parts of the shins, or tibiae- (Fig 19 D, e), open each into a small pocket (Fig. 20 A, E) with a tympanumlike membrane (Tm) stretched across its ;nner wall. Between the membranes are a*r cav ities (Tra) and a com-

pl eated sensory receptive apparatus (B) connected by a nerve through the basal part of the leg with the central nervous system. There are several groups of katydids, classed as sub-

0 0

Post a comment