260 S. (>. MAST 



five seconds. The relatively long abdomen hangs down nearly 

 vertically, with the posterior end turned slightly up, so as to- 

 fully expose the luminous tissue to creatures below. The females, 

 on the other hand, ordinarily remain quiet and do not glow 

 unless they are stimulated. If a male glows within a radius of 

 five or six meters of a female she usually responds almost im- 

 mediately 3 by producing a flash of light. The male then turns 

 directly toward her in his course and soon glow r s again. Fol- 

 lowing this the female again responds by glowing and the male 

 again apparently takes his bearing, turns and directs his course 

 toward her. This is repeated usually not more than two or 

 three times before he gets near her and lights. Then he runs 

 about in an apparently excited manner, glowing at irregular 

 intervals, but orienting after each response of the female and 

 proceeding toward her until his antennae come in contact with 

 her, after which copulation takes place at once and all lumi- 

 nescence ceases. It is a very simple matter to follow a series 

 of responses like this ending in copulation. The whole process 

 as described was seen in very many different cases. There 

 cannot be the slightest doubt as to the significance of the pro- 

 duction of light in the creature studied. 



If there is no wind the male usually lights within a few centi- 

 meters of the female, sometimes actually striking her. Thus 

 they may come together in a very short time. But if it is windy 

 the male frequently lights some distance from her and, especially 

 if he becomes entangled in grass and other vegetation, as often 

 happens, it may require many flashes of light, responses and 

 reorientations and repeated flights before he actually finds her.. 

 After the male lights he apparently becomes much excited, 

 as stated above, and usually runs about waving the antennae 

 quite actively. The intervals between the flashes of light pro- 

 duced are much more irregular than when he is on the wing. 

 During or immediately after each glow he stops, raises the an- 

 tennae, takes an attitude of apparent attention and remains per- 

 fectly quiet until after the female answers with a flash, then 

 he turns until he faces the direction in which the flash occurred 



3 McDermott says (1911, p. 400): " The answering of the female does not occur- 

 immediately after the Hash of the male, but at a period — apparently approximately 

 constant for all females of this species — of about three to four seconds after the 

 flash of the male. This slight delay occurred in every normal case of mating ob- 

 served with this species, pyralis." 



