1878.]  Fire-Flies and their Phosphorescent Phenomena. 663 
I have examined many of the Lampyridz; the phosphorescent 
segments in the highly organized species contain a translucent 
substance resembling half-cooked starch, situated just behind a 
yellow waxy-looking membrane. This membrane has, on its 
ventral aspect four distinct spiracles for the admission of air. 
Through these spiracles and contiguous parts may be seen at 
times quick brilliant flashes of light, made more rapid and vivid 
when the insect is handled, and followed in its normal state by a 
milder emanation, which may be compared to the embers of the 
previous conflagration. This second light is yellowish and dies 
out slowly. The first appearance of fire-flies in the twilight is 
indicated by a red, followed shortly by yellow, and later by the 
characteristic green light. 
Different species vary in the degree of activity and also some- 
what in the manner of emission. The phenomenon is also sub- 
ject to changes during the metamorphic period. 
The larva in Photinus emits a steady green light from the pos- < 
terior segments on the ventral surface. The pupa light, at first 
green, soon assumes a whiter less brilliant character, diffused over 
the entire body. 
The imago of the apterous female of Pleotomus exhibits greater 
intensity, and over a larger surface than in male forms, but steady, 
and at times disappearing from the posterior segments to be dif- 
fused as a white light over the body. This insect is scarcely 
more than an egg-bag, and its light is never so green as in other 
species. There is almost as great a diversity of degree and man- 
ner as of varieties, each enabling the observer to identify them at 
night. . 
A peculiar odor is perceptible, at times, in fire-flies. An 
English writer first noticed this, but afterwards concluded that he 
might have been mistaken. 
_ The soil which is most frequented by glow-worm larvæ con- 
sists largely of decomposed rocks, and produces a growth whose 
ash is intensely sulphurous to the taste. In these places may also 
be found earth-worms filled with phosphorescent matter, and 
snails, the favorite food of the glow-worm larve, while the Prim- 
ula mexicana, the vegetable diet of adult winged species, also 
abounds. All these features obtain in a moist soil and open air 
of fields, where, according to Ebermeyer, ozone is found in | 
greatest quantities, and oxygen its other form. . 
