BEHAVIOR OF FIRE FLIES 259 



thus, and there were probably fully as many more captured on 

 the wing of which no record was kept. The wings of the females 

 are, however, as previously stated, fully developed and they 

 appear to have no difficulty in flying. 



The males usually start to glow about ten minutes earlier in 

 the evening than the females. The average time of the first 

 glow for seven different days, not successive, between July 

 12th and 30th was 7 .-40^ P. M. for the males and 7:51 P. M. 

 for the females. The time of the day the first glow appeared 

 was surprisingly constant throughout the season. It was re- 

 corded on eighteen days between July 4th and 31st and on 

 nine of these days it appeared between 7 .-35 and 7 .-40 P. M. 

 Throughout the entire time the variation was onlv from 7:35 

 to 8 P. M. 



I have no evidence indicating that the fire-flies, as might be 

 expected appear earlier on dark, cloudy and rainy days than on 

 bright, clear days. Low temperature, however, seems to 

 retard their appearance. Specimens kept in darkness or in low 

 light intensity during the day did not become active earlier 

 than those under normal conditions. Males in darkness were 

 never seen to glow spontaneously during the day, although the 

 females were found to respond to artificial flashes of light at all 

 times, and on one occasion after several responses of females 

 to artificial light, a male nearby became slightly luminous and 

 then ran about in an apparently excited manner and glowed a 

 few times. 



From the time the first flash of light for the evening is seen 

 in the open the number of glows gradually increases until a 

 maximum is reached between 8:30 and 9 P. M., after which 

 there is a rather rapid decrease. Comparatively few flashes 

 were seen after 9:30 P. M. and only rarely one after 11, although 

 occasionally one was seen after midnight. 



Thus it appears that the activity of these creatures is a periodic 

 phenomenon to a considerable extent independent of immediate 

 environmental changes. 



REACTIONS 



The male insects fly about in a leisurely sort of way, gen- 

 erally from one to two meters above the ground and glow 

 as previously stated, at fairly regular intervals of approximately 



