Chap. X. Hemiptera and Homoptera. 281 



Order, Himiptera (Field-Bugs). — Mr. J. W. Douglas, who has 

 particularly attended to the British species, has kindly given me 

 an account of their sexual differences. The males of Kome species 

 are furnished with wings, whilst the fpmales are wingless ; the 

 sexes differ in the form of their bodies, elytra, antennse and tarsi ; 

 but as the signification of these differences are unknown, they 

 may be here passed over. The females are generally larger and 

 more robust than the males. With British, and, as far as 

 Mr. Douglas knows, with exotic species, the sexes do not 

 commonly differ much in colour ; but in about six British 

 species the male is considerably darker than the female, and 

 in about four other species the female is darker than the male. 

 Both sexes of some species are beautifully coloured; and as 

 these insects emit an extremely nauseous odour, tlieir con- 

 spicuous colours may serve as a signal that they are unpalat- 

 able to insectivorous animals. In some few cases their colours 

 appear to be directly protective : thus Prof. Hoffmann informs 

 me that he could hardly distinguish a small pink and green 

 species from the buds on the trunks of lime-trees, which this 

 insect frequents. 



Some species of Eeduvidse make a stridulating noise; and, in 

 the case of Pirates stridulus, this is said"^ to be effected by the 

 movement of the neck within the pro-thoracic cavity. Accord- 

 ing to Westring, Beduvius personatus also stridulates. But I 

 have no reason to suppose that this is a sexual character, ex- 

 cepting that with non-social insects there seems to be no use 

 for sound-producing organs, unless it be as a sexual call. 



Order, Bomoptera. — Every one who has wandered in a tropi- 

 cal forest must have been astonished at the din made by the 

 male Oicadse. The females are mute; as the Grecian poet 

 Xenarchus says, " Happy the Cicadas live, since they all have 

 " voiceless wives." The noise thus made could be plainly heard 

 on board the " Beagle," when anchored at a quarter of a mile 

 from the shore of Brazil ; and Captain Hancock says it can be 

 heard at the distance of a mile. The Greeks formerly kept, and 

 the Chinese now keep these insects in cages for the sake of 

 their song, so that it must be pleasing to the ears of some men.^' 

 The Cicadidae usually sing during the day, whilst the FulgoridsB 

 api,iear to be night-songsters. The sound, according to Landois,''^ 



'" Westwood, 'Mocern Class, of also, on the Fulgoridse, Kirby an( 



Insects,' vol. ii. p. 473. Spence, ' Introdact.' vol. ii. p. 401. 



*3 These particulars are taken ^^ * Zeitschrift fiir wissenschaft 



from Westwood's ' Modern Class, of Zoolog.' B. xvii. 1867, s. 152-158. 

 'jisects,' vol. ii. 1S40, p. 422. See, 



