VI IIETEROCERA HEPIALIDAE 399 



are swollen, being filled with glands for secreting the 

 odorous matter.^ This structure has led to the suggestion of 

 the generic name Phymatoims for the Insect. Turning to 

 other species of the genus, we find that the normal rela- 

 tive roles of the sexes are exhibited, but with considerable 

 diversity in the species. In H. lupulinns the males fly about 

 with rapidity, while the female sits on a stem and vibrates 

 her wings ; she thus attracts the males, but they do not 

 perceive her unless happening to come within three or four 

 feet, when they become aware of her proximity, search for and 

 find her. It is doubtful whether the attraction is in this case 

 the result of an odour ; it would appear more probable that it 

 may be sound, or that the vibration of the wings may be felt by 

 the male. 



In IT. sylvinus, H. velleda and H. pyrenaicns less abnormal 

 modes of attracting the males occur, the individuals of this latter 

 sex assembling in great numbers at a spot where there is a female. 

 In the first of the three species mentioned the female sits in the 

 twilight on the stem of some plant and vibrates the wings with 

 rapidity ; she does not fly ; indeed, according to Mr. Eobson, she 

 does not till after fertilisation move from the spot where she 

 emerged. In H. pyrenaicus the female is quite apterous, but is 

 very attractive to the males, which as we have said, assemble 

 in large numbers near her. Tlius within the limits of these 

 few allied forms we find radically different relations of the 

 sexes. 



1. The male attracts the female — (A) by sight {H. Jiurnuli) ; 



(B) by odour (H. hectv.s). 



2. The female attracts the male — (A) by vibration of wings 



(H. lupulinus and H. sylvinus) ; (B) without vibration, 



but by some means acting at a distance (^H. velleda, 



H. pyrenaieus~). 



Little or nothing is known as to the habits of the great 



majority of the more remarkable forms of the family. The 



gigantic Australian forms are believed to be scarcely ever seen on 



the wing. 



The Hepialidae differ from other Lepidoptera by very im- 

 portant anatomical characters. The absence of most of the 



^ Bertkau, SB. Vcr. Rlieinland, xxxvi. 1879, p. 288 ; and Arch. Naturg. 

 xlviii. i. 1882, p. 362. 



