MOTIONS OF INSECTS. 451 
concealed, instantly appear, and the laminze which terminate them being 
separated from each other as widely as possible, they begin their march, 
They employ their antennz, however, not as feelers to explore surround- 
ing objects,—their palpi being rather used for that purpose,—but, it should 
seem, merely to receive vibrations, or impressions from the atmosphere, to 
which these laminz, especially in the male cock-chafers, or rather tree- 
chafers (Melolonthe), present a considerable surface. Yet insects that 
haye filiform or setaceous antennz appear often to use them for exploring. 
When the turnip-flea (Hallica oleracea) walks, its antenne are alternately 
elevated and depressed. The same thing takes place with some woodlice 
Oniscide), which use them as tactors, touching the surface on each side 
with them, as they go along. This is not, however, constantly the use of 
this kind of antenne ; for I have observed that Telephorus lividus, —a nar- 
row beetle with soft elytra, common in flowers,— when it walks vibrates 
its setaceous antenne very briskly, but does not explore the surface with 
them. The parasitic tribes of Hymenoptera, 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.1_ But upon 
this subject I shall have occasion to enlarge when I treat of the senses of 
insects. Antenne are sometimes used as legs. A gnat-like kind of bug 
(Ploiaria vagabunda) has very short anterior legs, or rather arms; while the 
two posterior pair are very long. Its antenne 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 antenne 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 Xyela 
pusilla, a hymenopterous insect related to Xiphydria, uses its maxillary 
palpi as legs.§ Ihave observed that mites often use the long hairs with 
which the tail of some species is furnished, to assist them in walking. 
Another mode of motion with which many insects are endowed is 
jumping. This is generally the result of the sudden unbending of the arti- 
culations of the posterior legs and other organs, which before had received 
more than their natural bend. This unbending impresses a violent rotatory 
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 deter- 
minate velocity, opposed to its weight more or less directly.4 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 process; and others, again, by means of certain elastic ap- 
pendages 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 in- 
Stance. Orchestes and Ramphus ; the whole tribe of skippers (Haltica), and 
the splendid Asiatic tribe of Sagra®, &c, The object of these dispropor- 
tioned and clumsy thighs is to allow space for more powerful muscles, by 
1 Marsham in Linn. Trans. iii, 26. 
2 De Geer, iii. 824. ie 03 5 Brit. Ent. i, t. sxx. f. 4, 
* Cuvier, Anat. Comp. i. 396, ® Oliv. Batam. n. 90. t. i 
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