486 MOTIONS OF INSECTS. 



seem, merely to receive vibrations, or impressions from the atmosphere, to 

 which these laminae, especially in tlie male cock-chafers, or ratlier tree- 

 chafers (^Mdolonthce), present a considerable surface. Yet insects that 

 have filiform or setaceous antennae appear often to use them for explor- 

 ing. When the turnip-flea {Ilaltica oleracae) walks, its antennae are 

 alternately elevated and depressed. The same thint^ takes place with 

 some wood-lice (^O nisei dec), which use them as tactors, touching the sur- 

 face on each side with them, as they go along. This is not however con- 

 stantly the use of this kind of antennas ; for I have observed that 

 Telephorus lividus — a narrow beetle with soft elytra, common in flowers, 

 — when it walks vibrates its setaceous antennae very briskly, but does not 

 explore the surface with them. The parasitic tribes of Hymenopiera, 

 especially the minute ones, when they move, vibrate these organs most 

 intensely, and probably by them discover the insect to which the law of 

 their nature ordains that they should commit their eggs ; some even using 

 them to explore the deep holes in which a grub, the appropriate food of 

 their larva, lurks.^ But upon this subject I shall have occasion to enlarge 

 when I treat of the senses of insects. Antenna? are sometimes used as 

 legs. A gnat-like kind of bug (Ploiaria vagabunda) has very short ante- 

 rior legs, or rather arms ; while the two posterior pair are very long. Its 

 antennae also are long. When it walks, which it does very slowly, with 

 a solemn measured step, its fore-legs, which perhaps are useful only in 

 climbing, or to seize its prey, are applied to the body, and the antennae 

 being bent, their extremity, which is rather thick, is made to rest upon the 

 surface on which the animal moves, and so supply the place of fore-legs.^ 

 Mr. Curtis suspects that Xy da pus ilia, a hymenopterous insect related to 

 Xiphydria, uses its maxillary palpi as legs.^ I have observed that mites 

 often use the long hairs witli wiiich the tail of some species is furnished, to 

 assist them in walking. 



Another mode of motion wrth which many insects are endowed is jump- 

 ing. This is generally the result of the sudden unbending of the articu- 

 lations of the posterior legs and other organs, which before Jiad received 

 more than their natural bend. This unbending impresses a violent rota- 

 tory motion upon these parts, the impulse of which being communicated 

 to the centre of gravity, causes the animal to spring into the air with a 

 determinate velocity, opposed to its weight more or less directly.^ Various 

 are the organs by which these creatures are enabled to effect this motion. 

 The majority do it by a peculiar conformation of the hind legs ; others, 

 by a pectoral piocess ; and others, again, by means of certain elastic 

 appendages to the abdomen. 



The hind legs of many beetles are furnished with remarkably large and 

 thick thighs. Of this description are several species of weevils; for 

 instance, Orchestes and Ramphus ; the whole tribe of skippers (^Haltica), 

 and the splendid Asiatic tribe of Sagra^, Slc. The object of these dis- 

 proportioned and clumsy thighs is to allow space for more powerful mus- 

 cles, by which the tibiae, when the legs are unbent, are impelled with 

 greater force. In the Orihoptera order all the grasshoppers, including 



' Marsham in Linn. Trans, iii. 26. 



2 De Geer, iii. 324. 3 Brit. Eni. i. t. xxx. f. 4. 



* Cuvier, Anat. Comp. i. 396. » Oliv. Entom. n. 90. t. i. 



