FIRE-FLIES.
Some years ago an American gentleman, visiting in one of the large
cities of South America, was invited to a masquerade ball at one of the
finest private residences in the city. The ball-room was the garden,--a
veritable fairy-land abounding in plants of the most novel and
beautiful description,--and upon the grass had been laid an extended
platform for the dancers. It was moonlight when the festivities began,
and no artificial lights were used; yet at various intervals among the
flowers soft gleams appeared, apparently for ornament. Among the first
comers was a tall gentleman dressed in a style of several centuries
ago, a most picturesque costume; but what particularly attracted the
attention of the American were the decorations of this gentleman and
his companion. Around the broad-brimmed hat he wore a band of what
appeared, from a distance, to be gems, that flashed like diamonds,
presenting a magnificent appearance. The lady’s costume was still more
remarkable, being fairly ablaze with these brilliant scintillations.
As the evening wore on, he was presented to these maskers, when he
found that the light proceeded from innumerable luminous insects which
had been secured by delicate wires, and fastened upon the hat and the
lady’s dress.
About the garden, hundreds of the insects were confined in delicate
glass globes, which without emitting much light, added to the charm and
novelty of the surroundings.
In Vera Cruz these beetles are so commonly used as toilet ornaments
that they form an important article of trade; and the natives make a
business of catching them, and in a way that would seem to show that
the lights of insects are their means of recognition. The fire-fly
hunters provide themselves with long sticks, upon the end of which
is fastened a burning coal. This waved in the air attracts the
light-givers, and they are entrapped in a net. They are then placed in
a box covered with a wire netting, bathed twice a day in tepid water,
and at night fed with sugar-cane.
The insects utilized in this curious manner are
fire-flies,--distinguished from the lightning-bugs by the steady
glare they produce. And that the lights of these Elaters, as they are
scientifically called, is intense, and of practical value in other
ways, we may realize from the statement of Professor Jaeger, who
says, “I feel particularly grateful to these little insects, because,
during my excursions in St. Domingo, they were frequently the means
of saving my life. Often has dark night surrounded me in the midst of
a desert forest, or on the mountains, when the little animals were my
only guide; and by their welcome light I have discovered a path for my
horse, which has led me safely on my journey.” If a number are confined
in a glass, they emit sufficient light to read by.
It is in the genus _Pyrophorus_ that we find the most remarkable
light-givers; the different species being found principally in tropical
America. In Plate XI. _Pyrophorus noctilucus_, a form common in
the West Indies and Brazil, is shown. It ranges from 1.50 to 1.75
inches in length; is a black or rusty-brown color; and, if observed
during the daylight, two conspicuous oval spots of a yellowish white
hue are seen on each side of the prothorax. These are the lanterns of
the Elaters, and in the dark glow with a brilliancy far exceeding that
of the lightning-bugs. These lights shine from above, while between
the part known as the metathorax and the first abdominal segment
gleams another, or lower light, even more brilliant than the other:
so the _Pyrophorus_, turn which way it will in its flight, emits
a flash of light. The light appears to be dependent upon the will,
as when feeding or asleep it is not seen; attaining its greatest
brilliancy during activity and flight. The color of the light, as seen
by the author, is a rich green; but the eggs emit a light of a bluish
tint, according to Dubois. This naturalist has made some extremely
interesting experiments with this beetle. The eggs which he dried
retained their luminosity for a week, the light re-appearing when they
were placed in water. He ground the luminous organs in a mortar, after
having dried them in vacuum, and then mixed them in boiled water; the
latter immediately becoming luminous. Dr. Dubois concludes that the
light of the _Pyrophorus_ is intended as an illuminator for itself
alone. To prove this, he covered one of the upper lights with wax, and
the animal moved in a curve; when both spots were covered, the beetle
soon stopped, and then moved in an uncertain manner, carefully feeling
the ground with its _antennæ_. The spectrum of the light was
extremely beautiful, being continuous, without dark or brilliant rays;
and, what appears most remarkable, the composition of the light was
found to change with its intensity. As to the exact cause of the light,
how it is produced, the secret yet rests with Nature.
Dr. Kidder thus refers to the brilliancy of one of these wondrous
light-givers: “Before retracing my steps, I stood for a few moments
looking down into the Cimmerian blackness of the gulf before me; and,
while thus gazing, a luminous mass seemed to start from the very
centre. I watched it as it floated up, revealing in its slow flight the
long leaves of the palm _Euterpe edulis_, and the minuter foliage
of other trees. It came directly towards me, lighting up the gloom
around with its three luminosities, which I could now distinctly see.”
The insect was the _Pyrophorus noctilucus_; a longish click-beetle
of a dull blackish-brown color, and covered over with a short,
slight-brown pubescence. When walking or at rest, the chief light that
it emits proceeds from the two yellow tubercles on the thorax, so
conspicuous in dead specimens; but, when flying, another luminous spot
is discernible on the hinder part of the thorax, and this is continued
to the under side of the insect.
Ovideo says that the Indians travel in the night with these insects
fixed to their hands and feet; and that they spin, weave, paint, dance,
etc., by their light. In Prescott’s “Conquest of Mexico,” we are told
that in 1520, when the Spaniards visited that country, “the air was
filled with the _Cucujo_,--a species of large beetle, which emits
an intense phosphoric light from its body, strong enough to enable
one to read by it. These wandering flies, seen in the darkness of the
night, were converted, by the excited imaginations of the besieged,
into an army of matchlocks.”
[Illustration:
PLATE XII.
THE LANTERN FLY.
(_Fulgora lanternaria._)
According to Madame MERIAN, Marquis SPINOLA,
and others.]
At the time of the discovery of Hispaniola, Peter Martyr assures us
that the natives, in their night journeyings through the woods, were
in the habit of fastening a number of these light-givers to their
feet to light the way. On this occurrence Southey founds the incident
mentioned in “Madoc” where Coatel guides Madoc through the cave:--
“She beckoned, and descended, and drew out
From underneath her vest a cage,--or net
It rather might be called, so fine the twigs
Which knit it,--where, confined, two fire-flies gave their lustre.”