INfltODUCTlON, 



vii 



that m6st Writers on the subject, notice that only certain atmospheric 

 conditions are suitable for the purpose. I have myself noted that 

 warm evenings with a little wind are most suitable for the "assembling '* 

 of moths such as lodia vernaria etc., a condition one might suppose 

 favourable to the diffusion of the scent. Writing of " assembling " 

 with Amphidasys prodromaria, Mr. Hope Alderson says : " I have 

 seldom found the same $ of much use on the second night " and " one 

 slightly windy night I attracted a good number of males, and took the 

 same ? on the following evening, which was quite mild and warm 

 contrasted with the previous one. I waited by the bag fully two hours 

 without any result " (' Ent. Bee.,' i., p. 18). These statements appear to 

 point conclusively to two facts, first, that the males are attracted by 

 some scent, or why should not a virgin $ be as attractive on the 

 second night as the first ; secondly, that the odour is only of brief 

 duration in this species and soon disappears. Two dozen male Staur- 

 opus fagi, were attracted on one evening by a single female by the Kev. 

 Bernard Smith (< Ent. Rec.,' vol. i., p. 67), whilst almost every record 

 of " assembling " gives some hint as to some odour being the attraction. 

 Thus Mr. J. E. Eastwood records the capture of nine males of Bombyx 

 rubi in a few minutes, attracted by a female in cop. which proves that 

 " sight could not have led the males there," whilst Mr. Robson records 

 male Hepialus sylvinus flying down to the sand, to a spot whence a female 

 had emerged, the scent probably remaining sufficiently to attract the 

 males, and Mr. A. Robinson refers to the fact that species of Sesia will 

 not attract the males unless " restless " and " excited." Possibly 

 here, the scent is only diffused by the movement of the wings. This 

 would account for the fact that " restless " females attract readily, 

 whilst lethargic females fail to do so. It is beyond question, at any 

 rate, that these scent receptacles or glands are of direct sexual value, 

 and that certain butterflies and moths do emit odours. Scudder says 

 that they are " in a large measure confined to the male sex, and are 

 emitted through microscopic canals, which course through microscopic 

 glands at their base within the wing membranes." On the contrary, 

 in moths, I believe they are chiefly confined to the female sex, and I 

 will take Scudder's own illustration to prove my point. He says : 

 " Since these insects emit odours, they must also be able to perceive 

 them. The males of certain species among the Bombycidce will, of an 

 evening, enter in great numbers an open room, within which a female 

 of the same kind has been disclosed from its cocoon, entirely out of 

 sight and often at a great distance from her visitors. It is plain, that 

 in instances of this kind, known to every entomologist and too nume- 

 rous to mention, the sense of smell must be the sole directing agent " 

 (pp. 1051-1052). Just so, but surely it will be granted that it is the 

 females in these cases that attract the males. It is the females that 

 are hidden. It must be the scent from them that guides the males to 

 their hiding places. In many of these instances, certainly, there is no 

 odour which is perceptible to us, but it appears beyond question that 

 they have a delicate sense of smell by means of which they can detect 

 odours altogether inappreciable as far as we are concerned. But the 

 male does sometimes attract the female. It is the male Hepialus Jiectns, 

 that gives out its pineapple scent whilst gently hovering, and attracts 

 the female, which, when she comes within the scented area, flies against 



