March, I9I7-] WiLLIAMS : NoRTH AMERICAN LaMPYRID^. 19 



Other or they may not always be visible, I know nothing of the 

 later larval stages or of the pupa. 



The adult beetle is commonly regarded as non-luminous, and in- 

 deed this seems to hold true of the greater number of individuals. 

 One evening while I was examining a jar containing a number of 

 them, a single male was observed to bear a pair of faint yellowish 

 lights, hardly to be perceived beyond an arm's length, on the eighth 

 abdominal sternite, i. e., in the very same position and segment as the 

 larval lights. The glow was steady and sustained. This male was the 

 only specimen which shone (or could shine) of its own accord, but 

 by rough handling I was able to induce four other specimens to pro- 

 duce a very faint and evanescent glow. It seems probable that the 

 organs are almost non-functional or vestigial and represent those of 

 the larva. In the adult the chitin beneath, /. e., .ventral to the light- 

 organs, instead of being transparent, is strongly pigmented. 



Lucidota atra Fab.i 



This, like the preceding species, is diurnal, and in early summer 

 may be seen clinging to herbage or in slow flight. It is a delicate, 

 rather broad, depressed insect, 8-11 mm. long, with the antennal 

 joints broadly flattened. The general color is black with the lateral 

 edges of the prothorax broadly pinkish and yellowish. I found this 

 insect abundant at Melrose Highlands, Mass. It is luminous in all 

 its stages, although sometimes when freshly emerged it does not glow 

 strongly as an adult insect. 



The dull whitish eggs are subspherical and hardly differ from 

 those of Photimis. The larva also is rather similar, but differs in 

 being slightly more flattened above, and in the more angulate tergites 

 which are dilute or grayish black instead of shining black. The larva 

 of Lucidota is rather more suffused with pinkish but may be most 

 readily separated from PJiotinus in having the lateral edges of the 

 last two abdominal tergites very broadly whitish carneous. This pat- 

 tern, situated as it is on the^ luminous segment, permits the brilliant 

 yellowish green light on the eighth abdominal segment to shine dor- 

 sally as well as ventrally. The light is readily controlled and may 

 not be used for a long period even though the insect be roughlji 

 handled. Larvae in confinement often flash out quite suddenly if dis- 



' 1 Lucidota atra Fab., Ent. Syst., I, loi, 1798. 



