364 Correspondence. 



And also is it seriously contended that the separate sweet scents of the 

 three species of common white butterflies (in all cases possessed by the 

 males only) are used for female attraction ? If it is, my observations on 

 these species during the past summer have been singularly at fault, for 

 it was concluded that the exact opposite was the case. 



Whatever is the cause of sexual attraction in lepidoptera it is some- 

 thing very complex and at the same time completely under the control of 

 the possessor. The summer brood of Vanessa urIiccB pair on, or directly 

 after emergence, but the autumn brood, although the sexes fly freely 

 together during autumn, don't pair until the following spring.* 



This is a common habit also with many species of Autumn moths, of 

 which Cemslh vaccinii is a striking example. The species abound in the 

 large v/oods of the West Riding from early October until the following 

 April, and it is only in the later month when the moths are worn and 

 shabby that the desire to procreate becomes manifest. 



B. MoRLEY, Skelmanthorpe. 

 O^ 



Mr. J. W. Taylor in his able paper on this subject makes one or two 

 points which seem to need further discussion. In the first place he gives 

 to male butterflies scent-producing plume-scales and, secondly, he states 

 that it is the male which supplies the attractive force. The presence 

 of these scales and their specific character are of course undoubted, but 

 to my mind their establishment as secreting structures needs much faith. 

 It is difficult to see how any cell can take on a secreting function at all 

 unless it contains living protoplasm, or how it can carry on that function 

 for any length of time unless supplied with ' raw material ' through the 

 circulation. Are the scales of an insect living cells and do they receive 

 nutriment from the body-fluids ? I think not. 



That female insects attract the males by scent is to my mind in most 

 cases obvious, and the lack of obvious scent-glands cited by Mr. Morley 

 is no proof or indication to the contrary. The genital system is itself a 

 complex glandular structure which, no doubt, produces the scent secretion 

 with the other secretions necessary for the sexual functions. It is surely 

 in' accordance with what is known of vital processes in the. animal kingdom 

 that each system should be largely self-contained. Instances of male 

 animals being attracted by scent produced by female genital organs are 

 too numerous and obvious to need specific mention. 



I have seen nothing in the pairing of pierid butterflies to suggest that 

 the male supplies the attractive force, by which Mr. Taylor seems to 

 mean that scent produced by the androconia of the male attracts the fe- 

 male from a distance. If this be so it is easily capable of proof, but I 

 know of no exeriments or entomological tactics based on this belief. We 

 have all seen P. vapi $ at rest on a twig or the ground. Her wings may 

 be open or shut unless another butterfly flutters over the spot. In that 

 case the wings are held flatly open with the costal margins sloping black- 

 wards. If the visiting insect be a male the abdomen reaches up towards 

 him while he is still a foot or more away, the only evidence I have seen of 

 his attractive force. The male alights and investigates the female, copu- 

 lation following in some cases, but often not. 



In this insect the male seeks the female, finding her, I beUeve, by sight 

 only. At least I have never seen butterflies assembling to a hidden 

 female, as many moths do. Any of the pierids will fly down to investigate 

 a resting insect of their own sex or of different species, or a piece of white 



* Is Mr. Morley sure of this ? It is usually supposed that hibernating 

 lepidoptera pair in the autumn, after which the males largely die off. I 

 have no recollection myself of ever seeing a hibernated butterfly or moth 

 paired in the spring, and if Mr. Morley or any of your correspondents have 

 done so, it will be will for them to record the fact. — G.T.P. 



