406 THE INSECTA. <§> 327. 



The movements of the wings are produced by two extensor and several 

 smaller flexor muscles, which arise from the middle and posterior thoracic 

 segments, and are inserted on a tendinous process at the base of each wing. 

 The size of these muscles is proportionate to the size of the wings and their 

 mode of use in flight. They are, consequently, all equally developed when 

 the four wings participate equally in the act of flying, as is the case with 

 the Lepidoptera, Hymenoptera, the majority of the Neuroptera, the Libel- 

 ludidae, Perlidae, and finally, the Cicadidae, and the Aphididae. 



The muscles of the anterior wings are comparatively smaller than those 

 of the posterior, when the first are not used, properly speaking, except to 

 cover the latter, as is the case with the Coleoptera, the Bugs, and many of 

 the Orthoptera.*'-' 



With most of the Poduridae, and with the young larvae of Xenos sphe- 

 cidarum, there is a peculiar, fork-shaped, saltatory organ. It is inserted 

 on the posterior extremity of the body or under the abdomen, and, when 

 at rest, points horizontally backwards. By means of a special muscular 

 apparatus, this fork is bent forwards and applied against the abdomen ; it is 

 then returned violently into its original position, thereby tossing the animal 

 a considerable distance. ^^^' 



§ 327. 



Many of the Insecta produce sounds which we perceive partly as clear 

 tones, and partly as confused noises. These are due, sometimes to partic- 

 ular soniferous organs, but more often to vibrations of the cutanous skel- 

 eton produced by special muscular organs, or to the rubbing of certain 

 parts against each other. But in every case, without exception, the sound 

 is due to the action of voluntary muscles, and has no connection with the 

 respiratory organs.*" 



The buzzing produced by many Diptera, and Hymenoptera, during flight, is 

 due, without doubt, to vibrations of the thorax produced by the rapid and 

 successive contractions of the muscles of the wings in this act.*-> Further 

 researches are necessary to show if the sounds produced by certain butter- 

 flies are due to rubbings of some parts of the cutaneous skeleton, or to a 

 special soniferous apparatus.*^' But the sharp sounds of many Coleoptera 



12 For the flight of Insecta, see Straus, Con- of the wings, for it persists sometimes after the re- 

 sider. &c. p. 200 ; but especially the extensive moval of these last. Neither can it be attributed 

 work, illustrated with many figures, of Chabrier, to the rapid passage of air through the stigmata of 

 Mem. du Museum, VX.-VIII. the thorax, causing vibrations in that part of the 



13 See Nico/et, loc. cit. p. 39, PI. III. ; and my body. Burmeister, who has advocated this last 

 Beitrag. zur Naturg. d. wirbell. Thiere. p. 84, Taf. opinion (llandb. &c. I. p. 508, and in Pognen- 

 III. fig. 70. This fork is wanting in the genera dorf's Ann. d. Physik. XXXVIII. 1836, p. 283, 

 Achorutes and Anurophoras, as well as with Taf. III. fig. 7-9), compares these sounds to those 

 the. larvae of Stylops among the Strepsiptera. produced liy a siren ; but this theory has been 



1 Some Insecta produce sounds by striking or fully refuted by Goureau, Solier, and Erichson 

 rubbing certain parts of their cutaneous skeleton (see Silbermanii's Revue Entomol. III. p. 105, 

 against the body. 'ihsraaXes oi Mycterus curcu- and Ann. de la Sue. Entom.de France, VI. 1837, 

 lioidex knock with such violence the extremity of p. 31, and Wiegmann's Arch. 1838, II. p. 193). 

 their body against the boughs on which they have The various sounds of flies and bees may be imi- 

 alighted, that they produce a pretty loud sound, tated, moreover, by placing a vibrating tuning- 

 designed, probably, to call the females. fork in contact with a band of stretched paper, — 



The larvae of Vespa crabro, when hungry, an experiment in which the vibrations of the air 



scratch the walls of their cells with the point of their take no part. 



jaws, and thus call the attention of the parents to 3 It is said that, with Euprepia pudica, the pe- 



their condition. culiar sounds are produced by the rubbing of a 



2 The buzzing of these Insecta has been at- callosity of the two posterior hips against the mid- 

 tempted to be explained in various ways. At die hips {Solier, Ann. de la Soc. entom. loc. cit.). 

 all events, it cannot be due aloae to tlie movements The cry of Acherontia atropos has been attempted 



