58 



THE CANADIAN ENTOMOLOGIST 



when observed close at hand, is se'en not to be a continuous steady 

 flash, but a series of very rapid pulsations, or a flash of very rapid 

 variations in intensity, such as may be observed in a moving 

 mirror image of an arc-lamp operation on alternating current. (See 

 diagram). As compared with the phenomenon of the alternating 



1. Pyractomena 

 borealis. 



2. Pyractomena 

 angulata. 



.3. Pyractomena 

 iucifeia. 



4. Photinus 

 pyralis. 



o. Photinus 



consanguineiis. 



6. Photinus 

 scintillans. 



7. Pnotinus 

 marginellus. 



S. Photinus 

 castus. 



9. Photinus 



pennsylvanicus. 



Pig, 6. — Chart showing relative intensities and durations of flashes of American 

 Lampyridae. d cm. vertically equals approximately 0.02 candle power; 1 cm. 

 horizontally equals approximately one second in length of curves; space between 

 curves representing flashes of male and female of same spscies, is arbitrary. 



current arc-lamp, the "frequency" appeared to be about 50 per 

 second, rather slower than the lamp (60 cycles). One insect flash- 

 ing thus was caught on the evening of May 27, and found to be a 

 female, but at this time, none could be attracted to the electric light, 

 bv imitating either this flash, or that described in the preceding 



