FIREPLIES AND GLOW-WORMS AND THEIR LIGHT. 193 
Of late years much important work has been done by Mr, A. 
McDermott (*) upon North American species of Fireflies. These in- 
sects, popularly known as Lightning—bugs, resemble the Fireflies of 
Southern Europe mentioned above in that the male beetle flies about 
flashing his light, while the femle lurks in the grass below. But 
whereas in the case for example of the European L. italica the female 
would seem to shew her light on her own initiative to attract the 
attention of passing males, in the American Lightning-bugs (and also 
in the European species observed by Emery } the female is more 
modest, and shews her light only in reply to the “ calling ” flash of the 
male. Inthe United States the number of species is very considerable, 
and in many cases two or more of them have been found flying to- 
gether over the same ground, so that specific differences in the light 
exhibited have been evolved to a high degree. A female of one species 
will, as a rule, only reply to the flash of a male of her own species, and 
a searching male will only respond to the answering flash of a female 
of his own species. Specific differences are found to exist in the 
periodicity of the flash, in its colour, its duration or in its direction, 
some species rising and falling with a kind of dancing motion and 
omitting the flash on the dip or on the rise, ete. Mr. McDermott’s 
investigations were assisted by an ingenious series of experiments with 
small electric bulbs, which could be operated to simulate the flash of 
the particular species under observation. A brief summary of some of 
- his results may serve as a guide to similar enquires in other parts of 
the world. 
Photinus pyralis. The flash of the female is given 3 or 4 
seconds after that of the male, and is of the same colour but of longer 
duration and less intense. 
Females would answer in numbers to the flash of a match 
swung in an arc to simulate the flash of a male, though as a rule not 
more than one female would reply to a flashing male. 
A particular female would not reply tothe flash of a male of 
another species ( P. consanquineus ) though she would to that of a 
match. 
The male could also be deceived by a bulb placed in the grass 
and flashed 3 or & seconds after his own flash. When the bulb was 
flashed without the pause it was not so effective. 
(3) Canud. Ent, 1910-11-12. 
