?92 



THE CAUSE OF THE ATTRACTION IN THE 

 PAIRING OF LEPIDOPTERA. 



B. MORLEY. 



To Major Smart's interesting note on the pairing of Hepialus hectus, in 

 The Naturalist, p. 269, I should hke to make an observation. The species 

 in question pairs about sunset, and the couples hang from the underside 

 of the bracken fronds, but although they are fairly well concealed, the 

 quick eyes of the night-jar detect the easily obtained food supply, and by 

 gliding under the ferns, takes the unsuspecting moths into its spacious 

 gape as it flies along and procures a good meal without much trouble. 

 Although this takes place while it is still quite light, I have never noticed 

 the birds hawk after the flying moths of this species. 



With regard to the cause of attraction in the pairing of moths, in The 

 Naturalist for July, pp. 234-5, is a note of mine on the pairing of Hepialus 

 lupuliniis, where a suggestion is made that the wing vibrations of the 

 female are the means used for attracting the male to her. Anent this 

 suggestion is an editorial note unceremoniously sweeping it aside as a 

 fairy tale. Fairies, like ghosts and mermaids, are creatures that only 

 exist outside the hmits of cognition, and are the creation of minds which 

 think irrational thoughts, but why communication by means of vibration 

 should be classed with such mythical creatures is hard to understand. 

 Surely communication by means of the human voice and the various forms 

 of telegraphy are only possible by reason of vibrations. As regards sound 

 vibrations, they travel much further and more freely with the wind than 

 against it. Much research has recently been made into biological structure 

 of the various interior organs, and especially the genitalia of Moths, but 

 by the published accounts of the discoveries made scent glands are not 

 present in the bodies of the females, or if they are nothing is said about 

 them, \^'hy then, should the wing vibrations, which we know by ob- 

 servation are actually made, be discounted, and primary importance be 

 given to a scent which we cannot detect. Experience teaches us that 

 where scent is present in animals it is exuded from a gland, and the only 

 logical way of reasoning is by experience, otherwise it is mere speculation : 

 consequently, until such times as scent glands are proved to exist the scent 

 theory of attraction must be banished into the region where fairies dwell, 

 and in the meantime it may not be altogether profitless to work out the 

 possibilities of communication by vibrations as a necessary preliminary to 

 moth copulation. 



For a number of years the writer has been sceptical as to the generally 

 accepted theory of the cause of moths being attracted to light. One 

 fully realizes the gravity of attacking an old established theory and 

 expects much unreasonable condemnation for his temerity. Nevertheless, 

 for the sake of truth, risks are worth taking. The reason given as the 

 cause of this attraction is that all the facets composing the eyes become 

 filled or flooded with the rays of light, thus rendering the insect totally in- 

 capable of seeing anything except the light ; therefore, if it flies at all, it is 

 bound to fly to the light, because it is the only object it can see. Strange to 

 say, however, it is a fact that most of the moths thus attracted are males, 

 indeed, the extreme rarity of a female being found at light may safely be 

 dismissed as accidental. One has never seen a convincing explanation of 

 this well-known fact. Now, the females of each species of night-flying 

 moths have eyes identical in structure with those of the males, and so 

 far as one knows, they can see just as well as the males ; that they also fly 

 freely is manifest, for they visit the ' sugar ' patches in about the same 

 numbers as the males. While in the act of flying it is supposed that they 

 are just as liable to fly into the region near a light as the males are, and if 

 the illuminated facet theory is correct they should be just as liable as the 

 males are to light attraction, but the truth is that they are not so, and one 



Natu.au:>tr 



