298 NATURAL HISTORY. 



to it, namely, that of the Bm-ying-beetles, many of which ai - e seen engaged together in interring 

 carcases of small mammals, being only the accidental assembly of a number of individuals, generally 

 of different species, each intent on providing independently for its own young, just as a crowd of 

 Geotrupes will work together at a recent cow-dropping, or a swarm of Bark-beetles be attracted to a 

 newly-felled tree. Without reaching this high stage of development of insect intelligence, however, 

 Beetles display instinctive qualities of great perfection and diversity. This is manifested in the arts 

 resorted to by them in entrapping their prey ; as in the larva of the Tiger-beetle, which stations itself 

 in a hole it excavates in a sandy bank, and traps incautious flies who tread on the broad head of the 

 insect, that closes the orifice of the hole ; and also in the many contrivances adopted by the mother 

 insects for securing a supply of pabulum to their offspring, as in the dung-feeding scarabsei, and 

 the Sitaris, whose habits will be detailed farther on. The extensive prevalence of voice-organs in the 

 male insects of the order is a proof of a considerable amount of understanding between the sexes, the 

 sounds emitted being the calls of the insect to its mate. An excellent resume of this subject is given 

 by Mr. Darwin (" Descent of Man," Vol. I., pp. 378-384). The sounds produced are a kind of 

 stridulation, similar to, but less shrill, than that produced by Crickets and Grasshoppers. Although 

 very diverse in form and situation, the stridulating organs are all on a similar principle, which is 

 that of fiddle and bow, two contiguous parts of the body being mutually adapted for being 

 drawn or rubbed the one across the other. In the great family of Longicorus, the sound is 

 produced by the friction of the hind rim of the prothorax over a finely-ribbed prominence on the 

 mesothorax beneath. These ribs are microscopic, and M. Landois counted as many as 238 on 

 the rasp of Cerambyx heros, a common European Longicorn. Many species of this family will 

 stridulate vehemently from alarm, when held tightly between the finger and thumb. The sound is 

 faint in small species, but in the great Harlequin-beetle of tropical America stridulation is so loud that 

 it may be heard at some distance before the insect is seen. In the Necrophori, or Bury ing-beetles, the 

 organ is situated on the upper surface of the fifth abdominal segment, and consists of two narrow 

 finely-scored bands, which are rubbed by a ridge lying under the apical edge of the shortened wing- 

 covers. In Geotrupes, again, it is the haunches of the posterior legs which bear the fiddle, in the form 

 of a raised band, crossed by fine ribs, across which the hind margin of the third abdominal segment is 

 drawn by a short motion backwards and forwai-ds. These voice-organs exist in both males and females 

 in our common Geotrupes stercorarius, as in some other species of Beetles, and the stridulatiou, there- 

 fore, serves both sexes as a mutual call. It appears also to be used in some large species of Stag- 

 beetles as a note of anger or defiance. Some Beetles, on the other hand, produce a sound evidently 

 intended for communication with others of the same species, not by stridulation, but by ticking or 

 rapping, as in the well-known case of the Anobium, or death-tick, which burrows narrow galleries in 

 the wood of old furniture. When performing, the insect fixes itself firmly on its six legs, and then 

 taps against the wood by a series of hammering movements of the whole body, the hard mandibles at 

 each blow coming in contact with the wood. It is easy to induce the Anobium to tick, by imitating 

 the sound with the finger-nail on the wood, when it raps in response. 



The existence of sound-organs so curiously elaborated in so many Beetles belonging to different 

 families, implies a corresponding development of the sense of hearing. But although much observation 

 and study have been devoted to this subject, physiologists are not yet in accord as to the situation of 

 the hearing apparatus. The preponderance of opinion seems to be in favour of the antennae being 

 the ears in the insect class, although the evidence is not yet clear as to the existence of a tympanum 

 at their base. A fine surface sculpture in many of the joints of these organs, which presents 

 itself generally as minute pores, densely pubescent, is supposed to indicate an apparatus for the 

 reception and transmission of acoustic vibrations. In this point of view the minute structure of 

 the antennae becomes a very interesting study, deserving of more attention than has yet been paid to 

 it, especially as it is constant throughout the minor groups, and offers in those families where it has 

 been attended to excellent characters for natural classification. It is found, on investigation, that the 

 finely-sculptured, pubescent, or porous spaces are not often spread equally over the whole of the 

 organs, but are localised on some few of the joints, and in different situations, according to the species, 

 genera, or groups of genera. According to the celebrated anatomist Landois, the organ of hearing in 

 Stag-beetles is confined to small pits, situated one on each side of the terminal plate of the club. The 



