362 LUMINOUS ORGANISMS OF FAR EAST 



group, and last the lower group. Sometimes the rhythmical flashing 

 was transmitted from the lower part to the upper. The flashes were 

 repeated at the amazing speed of seventy per minute. The phenome- 

 non continued every day for one week while I was there, lasting 

 from sunset to dawn, notwithstanding the rain. It resembled the 

 description reported by Smith (1935), except that he noted the phe- 

 nomena occurring when the moon was half full. 



2. When a strong electric light was directed on them for a few 

 seconds the synchronous flashing became irregular. After thirty sec- 

 onds new synchronisms arose from some other groups in the tree 

 and extended over the whole tree. 



3. Fireflies on the tree were male and female in equal number. 

 This fact differs from the observations reported by Morrison (1929) 

 and Smith (1935). I observed about 100 males and females, each in 

 separate cages in the darkness. Only the males continued to flash 

 synchronously. On the contrary the females showed irregular flashing. 



4. Not only the luminous organs of the male and female, but the 

 color also, differ. The difference is discernible with the naked eye. 

 The color of the light of the males is yellow, while that of the females 

 is bluish green. Their light looked like scatterings of yellow and 

 bluish green powder when the tree. was shaken. 



5. Even after dawn, with the sun shining brighdy, the fireflies re- 

 mained on the leaves of the tree. 



6. This species of firefly selected thin-leafed trees. Sometimes these 

 fireflies flashed synchronously as they flew through the air. 



7. Many copulating fireflies were found on the grass under the tree. 

 At that time the males were not emitting light. In view of this ob- 

 servation, it seems the synchronous flashing is a behavior pattern by 

 which the males invite the females to a group. 



I do not believe there is any permanent leader in the group that 

 acts as a continual pacemaker for the synchronous flashing. I think 

 that when some individual or group emits light, it has a stimulating 

 effect that causes the light to spread throughout the whole group as 

 a wave. 



The larva of this firefly is terrestrial. I collected a luminous pupa 

 in the Botanical garden at Rabaul. 



In March, 1943, I saw again this beautiful synchronous flashing at 



