84 



KNOWLEDGE. 



[May 1, 1891. 



holes in stockiugs hung before the fire to dry, in order to 

 satisfy their cra\-ings for moisture. Hence, also, it is not 

 an infrequent experience to find them drowned in pans or 

 jugs of liquid. 



The House Cricket is more or less of a pale brown 

 colour throughout, and, unUke the cockroach, it is fully 

 winged in both sexes, and, therefore, has uo need of man's 

 agency to supplement its powers of locomotion. It flies 

 with an imdulatory motion, making long rising curves in 

 the air, and dropping at regular intervals. The wings are 

 extremely beautiful objects ; in fact, the house cricket 

 contains so many exquisite and deUcate structures, that 

 anyone who has a few hours to spare and can devote 

 them, with a good microscope, to the dissection of the 

 insect, will find ample material for interesting study and 

 observation. There are two pairs of wings, the upper pair 

 being more or less horny and exceedingly different in 

 males and females ; and the under pair thin and mem- 

 branous, and similar in both sexes. When closed, the 

 right upper wing partly overlaps the left, and the under 

 wings project in the form of long, tapering, rod-like 

 pieces beyond the tips of the fore wings, extending about 

 half as far again as these. 



The fore wings are much broader than a casual glance 

 would suggest, seeing that only about two-thu-ds of their 

 width lies flat along the back, the other third being bent 

 down at right angles to the rest, and Ijiug close along the 

 side. Those of the female are very regularly veined, 

 there being two systems of nervures proceeding in oppo- 

 site directions, one on each side of the stout ridge at 

 which the wing is bent. But the wings of the male 

 (Fig. 4) are extremely peculiar, and it is in them that the 

 power of chirping resides. There is the same division into 



Fig. i. — Right Fore wing of JIale Ckicket. a, line of bending ; 

 6, file ; c, drum. 



two areas as in the female, but the hinder section, i.e. the 

 one that lies on the back, has its veins distributed very 

 irregularly. A stoutish nervure runs straight across this 

 near its base, and then beyond it a large clear triangular 

 area is left almost devoid of nervures. At the apex of 

 this, nearer still to the tip of the wing, is another similar, 

 but smaller and four- sided, patch, with a single, pale, 

 delicate nervure rimning across it, and the rest of the 

 wing is covered pretty closely with a network of nervures. 

 If, now, these wings be turned over and examined beneath, 

 it will be found that the straight nervure aforesaid is 

 crossed transversely by a large number of little hard 

 ridges, gi\ing it the appearance of an extremely fine file. 

 These are much too small to be seen with the naked eye, 

 but a moderate magnification coupled with careful focus- 

 sing soon brings them into view. When the chirping is 

 to be produced, the insect bends the fore part of the body 

 shghtly downwards, and then slightly raising the fore 

 wings, rubs them rapidly across one another ; durmg this 

 motion, the file of one rubbing against the surface of the 

 other produces a creaking ^-ibration, which is greatly in- 

 tensified by the clear, open plates above-mentioned, w'hich 



are therefore called " drums." It wiU now be evident why 

 the females are mute ; they have neither " file " nor 

 " drum," and hence are physically incapable of " singing." 

 It is clear from the above that the chirping is in no 

 true sense of the word either a voice or a song, being 

 quite unconnected with the respiratory organs ; it is a purely 

 external and mechanical sound, comparable, as a means 

 of expressing sentiments, rather with the human device ot 

 clapping the hands, or flipping the fingers, than with the 

 utterance of sounds with the mouth. Of course it is not 

 to be expected that an insect should make any noise with 

 its mouth other than that produced by eating, since the 

 mouth does not, as is the case with us, commimicate with 

 the breathing organs. The entrances to these are in the 

 cricket, as in aU other insects, along the sides, and any 

 sound that might be produced in them by the passage in 

 and out of the air would be more strictly comparable with 

 the voice of vertebrate animals ; some insects, as for 

 example, the common bluebottle-fly, are able to produce a 

 noise in this way, and may therefore be truly said to 

 possess a voice. But that is by no means the rule, and 

 the soimds insects produce are in general the restilt of the 

 friction of external parts upon one another. 



The hind wings of the cricket are exceedingly delicate, 

 and are each strengthened by about fifty nervures radiating 

 fan-wise from the base. As about half these neirvures are 

 weaker than the rest, the weak ones being placed alter- 

 nately with the strong ones, the whole wing cau be folded 

 up lengthwise like a fan, and this accounts for its pointed 

 form as it protrudes from beneath the upper wing. It is this 

 jjeculiar method of straight, longitudinal folding that has 

 caused the name Orthoptera (N/c'/iV/Zif-winged) to be given 

 to the order. 



Of course the power of chirping implies the power of 

 hearing. It is only natural to suppose that the male 

 crickets would long ago have abandoned the habit of 

 serenading (if, indeed, they had ever perfected it) if their 

 mates had not been able to recognise their attentions. It 

 is rather curious, however, that this insect, notwithstand- 

 ing its hving in our houses, and the con- 

 siderable cm'tailment of its field of quest 

 for partners consequent thereupon, should 

 have preserved almost as strongly as its out- 

 door relative this power of chirping ; one 

 cannot help feeling a suspicion that, if this 

 vigorous minstrelsy be merely of an amatory 

 nature, either the gentler sex in the cricket 

 world have become extremely coy, or else 

 there is a vast deal of wasted energy on the 

 part of their swains. However that may 

 be, as the power of recognition of this call 

 seems as though it must be an important 

 matter in cricket economy, we naturally 

 look about for some special apparatus suit- 

 able for the detection of soimds, of a much 

 more indubitable character than is generally 

 met with in insects. .\nd the search is soon 

 rewarded. It is only necessary to examine the 

 tibia, or shank, of the fore legs, just below its 

 jimction with the thigh, to find an organ to 

 which it is diiiicult to assign any other function. Here, 

 on the flattened outer edge is a long, oval, transparent, 

 membranous disc, stretched over a corresponding aperture 

 in the walls of the leg (Fig. 5), and exactly opposite it, on 

 the other side of the leg, there is a sunilar, but roimd and 

 much smaller disc ; between these two. in the centre of 

 the hollow shaft of the leg, is a bladder-like expansion of 

 the main breathing-tube of the leg. Numerous curiously 

 shaped neiTe- endings, having the peculiar form of those 



