304 The Ecologic Relations of the Photogenice Function among Insects. 
Östen-Sacken’s work at the time, MeDermott (11) recorded 
observations on the mating of Photinus pyralis very similar to those of 
Östen-Sacken. He found further that it was possible to cause light- 
emission from either sex by {Ihe proper operation of a small electric 
lamp in imitation of the opposit sex, or from the females by flaslıes of 
light from other sources, such as a match. A slight pause was found 
to intervene between the flash of the male and the answering flash of 
the female. MeDermott (11, 12) extended his observations to Photinus 
consanguineus, P. scintillans, P. marginellu, P. castus and Lecontea 
lueifera. 
In Photinus consanguineus the flash of the male, instead of being 
single, is composed of two distinct coruscations, while that of the female 
is a single flash like that of the female pyralis; the female consanguineus 
would answer only to a double flash. In P. scintillans and P. castus, 
both smaller species than P. pyralis, the flashes of the male and female 
are both single, and of rather shorter duration than that of pyralis; 
the ranges of the two species appear 1o overlap, though they were not 
found together. P. castus and P. marginellus were found in the same 
habitat; the manner of light-emission of the males of the two species 
differs only slightly, that of marginellus being a trifle sharper. The fe- 
males, however, appear to distinguish between them readily, and the 
answering flashes of the two females are quite different. The flash of 
the female castus is a single flash, as described above, following the 
flash of the male by a very short pause; that of the female marginellus 
is a distinctly double flash, the two maxima following each other clo- 
sely. With the idea of making these differences somewhat clearer, the 
accompanying diagraım has been drawn, in which the abeissae represent 
time, one second to the centimeter, while the ordinates represent lumi- 
nous intensity, one centimeter equalling approximately 0.02 candle- 
power. 
Photinus castus was first described by Leconte as a separate species, 
but was later classed by him as a variety of marginellus. On account 
of the differences in light-emission, McDermott (13) has restored it - 
to the position of a distinct species. 
Green (6) has recently described the mating of Dioptoma adamsii; 
In this species the luminous organ of the female is, as usual, ventral, 
but the Juminosity is rendered more effective by curling the abdomen 
over the dorsal, so as to expose the surface of the luminous apparatus 
upwards. The abdomen is returned to the normal position upon the 
approach of the male. In this case, as in Lampyris noctiluca, the fe- 
male is larger and brighter than the male. 
The conduct of the Lampyridae toward artificial light is of interest. 
Both MeDermott (11, 12) and Mast (10) have shown that the species 
of Photinus may be deceived by small artificial lights operated in imi- 
tation of the opposit sex. They are, however, practically unaffected by 
ordinary continuous lights. The writer has seen a male Photinus pyralis 
fly past an open arc-light, within about 1.25 meter of the arc, without 
showing the least sign of attraction toward it. On one occasion a de- 
cided attraction toward an oil lamp was observed on the part of a male 
of Lecontea lucifera. Lund (8) has observed that the Jamaican species 
Photinus pallens shows a very slight attraction toward ordinary lights. 
On the other hand, the males of Lampyris noctiluca have long been 
w B 7320. Er. nm ae, 
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