The Bionomics of South African Insects. 539 



ground and was sharply fluttering lior wings to keep off 

 the male which was hovering above her. Whenever she 

 rested for a moment with open wings the male would 

 drop down on her, trying to settle on the costa of her fore- 

 wing in such a position that the badge on his hind-wing 

 came directly down on her head ; and while hovering over 

 her, his position was usually at right angles to hers, which 

 renders it probable that the badge is some sort of scent- 

 gland used for attractive purposes. The female however 

 kept on fluttering pretty incessantl}^ and the male kept 

 bumping down on her. Then anotlier male came round 

 and the first one went off and had a skirmish with him 

 and drove him away. The female then took flight, the 

 male usually keeping above her and trying to beat her 

 down to the g:round acjain. The female, on settling, 

 renewed her defensive fluttering, and the male, apparently 

 getting tired, flew off. The whole observation occupied 

 five minutes. I never saw any use made by the male of 

 his curious terminal tufts. 



B. The possible meaning of the Sac of Female 

 Acrseinm. 



Malvern, May 14, 1897. — The species in which the sac 

 is best developed are Acrxa neohide and A. horta. With 

 regard to the use of the organ, I remember making some 

 observations at Salisbury in 1894 on A. caldarena and 

 A. nohara-liahdi while ovipositing, and I then came to 

 the conclusion that the sac was of no use during laying, 

 being apparently rather an obstruction than otherwise. I 

 therefore rather incline to your second suggestion, that it 

 is probably to prevent copulation a second time. This 

 view moreover seems to be borne out by what I have 

 noticed in the courtsliip of the insects. So far as I have 

 at present observed, Acrseas appear to be the only butter- 

 flies which indulge in the system of " marriage by capture." 

 In such of the Nyniphalinx as I have watched, the males 

 have in no case attempted to seize the females, which, 

 when anxious to escape their addresses, did so either by 

 dodging aixiong the vegetation or soaring. The females of 

 some Picriii/f? (notably Belenois, Pinacopteryx) have a very 

 noticeable method of refusing the males; they settle with 

 wings outspread but with fore-wings directed backwards 

 so as almost to cover the hind-wings, and the abdomen is 



