458 MODERN CLASSIFICATION OF INSECTS. 



insects resting on their four anterior legs during the operation ; the 

 veins of the wing-covers being considerably elevated, so as to be 

 easily acted upon by the rugose inner edge of the thigh. Some spe- 

 cies, according to Goureau, may be observed to execute this move- 

 ment without producing any sound perceptible to our ears, but which 

 he thinks may be perceived by their companions. 



The pupa of one of these insects is represented in fig. 6Q. 14. 

 Many of the species of this family present on each side of the 

 body, near the base of the abdomen, a large cavity, closed on the 

 inside by a very slender skin of a whitish colour i^fig. 56. g. meta- 

 thorax and basal segment of abdomen, — a the femoral cavity, b the 

 membrane.) Latreille has described this organ in the eighth volume 

 of the Memoires du Mus. d' Hist. Nat., and which he (as well as 

 Llnnfeus, Burmeister, and others) considers must have a certain 

 influence either upon the act of stridulation, or during flight. M. 

 Goureau, however, considers that the sound is alone produced by the 

 friction of the thighs and wing-covers. {Ann. Soc. Ent. de France, 

 1837, p. 57.) These cavities exist also, but less perfectly developed, 

 in the larva and pupa states, according to this author, who enter- 

 tains the opinion that they may possibly be the analogues of 

 ears. The genus Tetrix {fig. 5Q- 16.) does not appear to be mu- 

 sical ; neither are the females of the Locustida?, although they may 

 be occasionally perceived rubbing their thighs and wing-covers toge- 

 ther. The females envelope their eggs (which, according to Zet- 

 terstedt, are three lines long in L. migratoria) with a glutinous 

 secretion, so as to form a cocoon-shaped mass, which they are said 

 by Latreille to attach to various plants. Solier, however, states, 

 that they are deposited in horizontal tubes of earth, coated with a 

 glutinous secretion, terminating in a cell an inch and a half deep ; 

 each tube holding from fifty to sixty eggs, or from eighty to a 

 hundred, according to Smernove, in Linii. Trans, vol. xv. p. 507. 

 In the south of Europe rewards are offered for the collection both of 

 the eggs and perfect insects — half a franc being paid for a kilo- 

 gramme of the former, and a quarter of a franc for the same measure 

 of the latter ; at this rate the city of Marseilles paid, in l(il3, 20,000, 

 and Aries 25,000 francs; in 1824-, 554-2, and in 1825, 6200 francs 

 were paid by Marseilles. (Solier, in Ann. Soc. Ent.'de France, torn. ii. 

 p. 486.) The Turks also send out bodies of peasants to destroy the 

 locusts ; and from a curious Chinese document, published in the 



