THE CANADIAN ENTOMOLOGIST 53 



L. . ___ . 



OBSERVATIONS ON THE LIGHT-EMISSION OF 

 AMERICAN LAMPYRID^: 



The Photogenic Function as a Mating Adaptation; 5th Paper. 



BY F. ALEX. MCDERMOTT, WASHINGTON, D.C. 



The following paper embraces the results of some observations 

 made since the fourth paper in this series was published. (See 

 Canadian Entomologist, 1910, vol. 42, p. 357; 1911, vol. 43, p. 399; 

 1912, vol. 44, p. 73; 309.) 



1. Pyractomena borealis Randall. (*) The presence of this 

 species in the neighbourhood of Washington, D.C, was established 

 by Mr. W. S. Fisher, who found it pupating in large numbers in 

 deep crevices in bark at Great Falls, on the Potomac River, about 

 fifteen miles northwest of the U. S. Capitol at Washington. It is 

 quite a large Lampyrid, and its flash appeared to the writer to be 

 the brightest of any of the known local fireflies. When flying at a 

 height of from eight to ten feet above the ground, its flash produced 

 a distinct though faint illumination over an area perhaps ten feet 

 in diameter on the ground. 



The distribution of the luminous organ in this species is ver\- 

 similar to that in P. angnlata and P. lucifera. In the male, the 

 entire ventral surfaces of the two segments before the last show the 

 yellow colour of the luminous tissue, while in the female this tissue 

 area is restricted to two irregular patches on these segments. The 

 male should, therefore, give distinctly the brighter light. The 

 habit of the insects of pupating in crevices in bark several feet 

 from the ground, as observed by Fisher, together with the known 

 reluctance of many female lampyrids to fly, ev^en when possessing 

 wings, would make it seem probable that the females would be found 

 on the bark of the trees where they emerged, or not very far away. 



* In a former paper the writer adopted the late E. OHvier's name Lecontea 

 for this genus. OHvier's reasons for the change, however, appear to be invalid, 

 according to Rule 36 of the International Commission on Zoological Nomen- 

 clature. As a matter of interest it may be mentioned that Mr. H. S. Barber, 

 of the U. S. National Museum, calls my attention to the fact that the name 

 Pyractomena was originally applied by Dejean (1833) to a genus containing 

 only manuscript names of species. Leconte, in 1850 applied this generic name 

 to Lampyris borealis Randall, a described species, which therefore automatically 

 became the type for this genus. This publication antedates that iisually given, 

 Leconte, 1852. The other species, lucifera and angulata, are canectly placed 

 in this genus. 



February, 1917 



