400 THE CANADIAN ENTOMOLOGIST. 



year, observations and experiments have been made which leave little 

 doubt that in at least four species in two of the genera, Lecoiitea and 

 P/ioiinus, grouped under E. Olivier's sub-family F/iotini?ii, the photogenic 

 function serves as a mating adaptation. 



The first observations were made upon Photinus pyralis. It was 

 soon found to be easy to recognize the flash of a female in answer to that 

 of a male flying above her, but it was not so readily determined that her 

 answering flash had any effect upon the actions of the male. The flash of 

 the female, while of the same colour as that of the male, is easily recog- 

 nized after a little practice, being slower — or rather of longer duration — 

 and less intense. Persistent watch, however, was rewarded by seeing the 

 male drop, following the answering flash of the female, flash again and 

 drop still lower after her second answer, alight a few inches away from 

 her, crawl toward her slowly, flashing at intervals — to each of which 

 flashes she responded — and finally locate and copulate with her. The 

 complete mating process was not followed until after several failures, 

 where the male, after dropping, would rise again, or would simply fail to 

 locate the female definitely, and fly away ; but since being observed once, 

 the same entire process has been witnessed a number of times, and under 

 somewhat diff'ering conditions. Apparently the males frequently locate 

 the females by flashing before either has flown, since insects may be taken 

 in copulation before the beginning of the period of flight in the evening. 

 In fact, on one cool, damp evening, when but few insects flew, while the 

 majority crawled to the tops of blades of grass and remained there, 

 flashing at intervals, several instances were witnessed of this mating with- 

 out flying. But the usual process appears to be as described first — the 

 male flies over the tops of the grasses, weeds, etc., dropping down 

 between them and flashing ; any females that come within the range of his 

 flash, answer by their slower flash ; if the male sees this answering flash from 

 one, he approaches her, flashes again, to which she answers, and he then 

 finally locates her definitely by means of subsequent flashes. The 

 answering flash of the female does not occur immediately after the flash 

 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 

 observed with this species, /_)/;'«//.?. 



To test this matter further, and to see if the females were sensitive to 

 flashes of light in the field, as had been observed in the laboratory, a 

 number of safety matches were ignited at irregular intervals, above an 



