452 MOTIONS OF INSECTS. 



which the tibiae, when the legs are unbent, are impelled with greater force. 

 In the Orthoptera order, all the grasshoppers, including the genera Gryl- 

 lotalpa, Gryllus, Tridactylus, Locusta, Acrida, Pterophylla, Pneumora, Trux- 

 alis, Acrydium, Tetrix, &c., are distinguished by incrassated posterior 

 thighs ; which, however, are much longer, more tapering and shapely 

 (they are indeed somewhat clumsy in the two first genera, the crickets), 

 than those of most of the Coleoptera that are furnished with them. When 

 disposed to leap, these insects bend their hind leg so as to bring the shank 

 into close contact with the thigh, which has often a longitudinal furrow 

 armed with a row of spines on each side to receive it. The leg being thus 

 bent, they suddenly unbend it with a jerk, when, pushing against the plane 

 of position, they spring into the air often to a considerable height and 

 distance. A locust, which, however, is aided by its wings, it is said will 

 leap two hundred times its own length. 1 Aristophanes, in order to make 

 the great and good Athenian philosopher Socrates appear ridiculous, re- 

 presents him as having measured the leap of a flea. 2 In our better times 

 scientific men have done this without being laughed at for it, and have 

 ascertained that, comparatively, it equalled that of the locust, being also 

 two hundred times its length. Being effected by muscular force, without 

 the aid of wings, this is an astonishing leap. There are several insects, 

 however, which, although they are furnished with incrassated posterior 

 thighs, do not jump. Of this description are some beetles belonging to 

 the genus Necydalis (CEdemera Oliv.), in which this seems a peculiarity 

 of the male, and amongst the Hymenoptera, not to mention others, several 

 species of Chalcis, and all that are known of that singular genus Leucospis. 

 Many insects, that jump by means of their posterior legs, have not these 

 thighs. This is said to be the case with Scaphidium, a little tribe of 

 beetles 8 : and one of the same order, that seems to come between Anobium 

 and Ptilinus, found by our friend the Rev. R. Sheppard, and which I have 

 named after him Choragus Sheppardi, is similarly circumstanced. In the 

 various tribes of frog-hoppers (Cercopidcs, &c.), the posterior tibiae appear 

 to be principally concerned in their leaping. These are often very long, 

 and furnished, on their exterior margin, with a fringe of stiff hairs, or a 

 series of strong spines, by pressing which against the plane of position they 

 are supposed to be aided in effecting this motion. On this occasion they 

 bend their legs like the grasshoppers, and then unbending kick them out 

 with violence. 4 Many of them, amongst the rest Anthrophora spumaria, 

 have the extremity of the above tibiae armed with a coronet of spines ; 

 these are of great use in pushing them off when the legs are unbended. 

 This insect, when about to leap, places its posterior thighs in a direction 

 perpendicular to the plane of position, keeping them close to the body ; 

 it next with great violence pushes them out backwards, so as to stretch 

 the leg in a right line. These spines then lay hold of the surface, and by 

 their pressure enable the body to spring forwards, when, being assisted by 

 its wings, it will make astonishing leaps, sometimes as much as five or six 

 feet, which is more than 250 times its own length ; or as if a man of 

 ordinary stature should be able at once to vault through the air to the 

 distance of a quarter of a mile. Upon glass, where the spines are of no 



i Swamm. Bill Nat. Ed. Hill, i. 123. b. 



8 Aristoph. Nubes, Act. i. Sc. 2. 



* Trost, Beitrage, 40. 4 De Geer, iii. 161. 



