Chap. X. 



Insects. 



*77 



unique as far as known to Mr. Wollaston, of the head of the 

 female being much broader and larger, though in a variable 

 degree, than that of the male. Any number 

 of such cases could be given. They abound 

 in the Lepidoptera: one of the most extra- 

 ordinary is that certain male butterflies 

 have their fore-legs more or less atrophied, 

 with the tibia3 and tarsi reduced to mere ru- 

 dimentary knobs. The wings, also, in the two 

 sexes often differ in neuration, 10 and some- 

 times considerably in outline, as in the Ari- 

 roris epitus, which was shewn to me in the 

 British Museum by Mr. A. Butler. The males 

 of certain South American butterflies have 

 tufts of hair on the margins of the wings, 

 and horny excrescences on the discs of the 

 posterior pair. 11 In several British butter- 

 flies, as shewn by Mr. Wonfor, the males alone 

 are in parts clothed with peculiar scales. 



The use of the bright light of the female 

 glow-worm has been subject to much discus- 

 sion. The male is feebly luminous, as are the 

 larvae and even the eggs. It has been sup- 

 posed by some authors that the light serves to 

 irighten away enemies; and by others to 

 guide the male to the female. At last, Mr. 

 Belt X2 appears to have solved the difficulty ; 

 he finds that all the Lampyridae which he has 

 tried are highly distasteful to insectivorous 

 mammals and birds. Hence it is in accordance 

 with Mr. Bates' view, hereafter to be explained, 

 that many insects mimic the Lampyridae 

 closely, in order to be mistaken for them, and 

 thus to escape destruction. He further be- 

 lieves that the luminous species profit by 

 being at once recognised as unpalatable. 

 It is probable that the same explanation may be extended to the 



Fig. 10. Taphroderes 

 distort us (.much en- 

 larged). Upper fig- 

 ure, male ; lower 

 figure, female. 



10 E. Doubledav, ' Annals and 

 Mag. of Nat. Hist.' vol. i. 1848, p. 

 379. I may add that the wings in 

 certain Hymenoptera (see Shuckard, 

 ' Fossorial Hymenop.' 1837, pp. 39- 

 43) differ in neuration according to 

 sex. 



11 H. W. Bates, in ' Journal of 

 Proc. Linn. Soc' vol. vi. 1862, p. 



74. Mr. Wortfor's observations are 

 quoted in ' Popular Science Review,' 

 1808, p. 343. 



12 'The Naturalist in Nicaragua,' 

 1874, pp. 316-320. On the phos- 

 phorescence of the eggs, see 'Annals 

 and Mag. of Nat. Hist.' 1871/ Nov., 

 p. 372. 



