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 animak 
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.” 
12 For’ the flight of Insecta, see Straus, Con- 
sidér. &c. p. 200; but especially the extensive 
work, illustrated with many figures, of Chabrier, 
Mém. du Muséum, VI.-VIII. 
13 See Nicolet, loc. cit. p. 39, Pl. III. ; and my 
Beitrag. zur Naturg. d. wirbell. Thiere. p. 84, Taf. 
III. fig. 70. This fork is wanting in the genera 
Achorutes acd Anurophorus, as well as with 
the larvae of Stylops among the Strepsiptera. 
1 Some Insecta produce sounds by striking or 
rubbing certain parts of their cutaneous skeleton 
against the body. The males of Mycterus curcu- 
lioides knock with such violence the extremity of 
their body against the boughs on which they have 
alighted, that they produce a pretty loud sound, 
designed, probably, to call the females. 
The larvae of Vespa crabro, when hungry, 
scratch the walls of their cells with the point of their 
jaws, and thus call the attention of the parents to 
their condition, 
2The buzzing of these Insecta has been at- 
tempted to be explained in various ways. At 
all events, it cannot be due alone to the movements 
But the sharp sounds of many Coleoptera 
of the wings, for it persists sometimes after the re- 
moval of these last. Neither can it be attributed 
to the rapid passage of air through the stigmata of 
the thorax, causing vibrations in that part of the 
body. Burmeister, who has advocated this last 
opinion (Handb. &c. I. p. 508, and in Poggen- 
dorf?’s Ann. d. Physik. XXXVIITI. 1836, p. 283, 
Taf. III. fig. 7-9), compares these sounds to those 
produced by a siren; but this theory has been 
fully refuted by Goureau, Solier, and Erichson 
(see Silbermann’s Revue+ Entomol. III. p. 105, 
and Ann, de la Soc. Entom. de France, VI. 1837, 
p. 31, and Wiegmann’s Arch. 1838, IL. p. 193). 
The various sounds of flies and bees may be imi- 
tated, moreover, by placing a vibrating tuning- 
fork in contact with a band of stretched paper, — 
an experiment in which the vibrations of the air 
take no part. 
8 It is said that, with Euprepia pudica, the pe~ 
culiar sounds are produced by the rubbing of a 
callosity of the two posterior hips against the mid- 
die hips (So/ier, Ann. de la Soc. entom. loc. cit.). 
The cry of Acherontia atropos has been attempted 
