Of those diamonds of the night, the fire-flies and fire-beetles, there
are numerous species. One of the most abundant--and of much larger
dimensions than the rest of the elaters or beetles--pyrophorus
noctilucus, called by the natives cocuja, displays both red and green
light. On the upper surface of the thorax there are two oval tubercles,
hard and transparent, like bull's-eye lights let into a ship's deck.
These are windows out of which shine a vivid green luminousness, which
appears to fill the interior of the chest. Then on the under surface of
the body, at the base of the abdomen, there is a transverse orifice in
the shelly skin, covered with a delicate membrane, which glows with a
strong ruddy light; visible, however, only when the wing-cases are
expanded. It is about an inch and a half long, of a brown colour, and
has a strong spine situated beneath the thorax, which fits at pleasure
into a small cavity on the upper part of the abdomen. By means of this
machine it can, when placed on its back, spring up a couple of inches,
and regain its feet. When preparing to do this it moves its head and
thorax backwards, so that the pectoral spine is drawn out and rests on
the edge of the sheath. The same backward movement being continued, the
spine, by the full action of the muscles, is bent like a spring, and the
insect at this moment rests on the extremity of its head and wing cases.
The effort being suddenly relaxed, the head and thorax fly up, and in
consequence the base of the wing-cases strike the supporting surface
with such force that the insect by the reaction is jerked upward, while
the projecting points of the thorax and the sheath of the spine serve to
steady the whole body.
So brilliant is the light of these creatures, that even one moved over
the print of a book wall enable a person to read by it, while eight or
ten placed in a clear glass bottle serve the purpose of a lamp. The
Brazilian ladies ornament their dresses with these fire-beetles, by
securing them so as not to injure the creatures; while they frequently
wear several in the braids of their dark hair, which, when they walk
abroad in the evening, has a curious and beautiful effect. [Gosse and
Darwin.]
Prescott relates that when the Spaniards first invaded America, on
seeing the air filled with cocujas during the darkness of night, their
excited imaginations converted them into an army with matchlocks, and
they waited, expecting to be attacked by an overwhelming force. A
similar story is told of the British, when first landing in the West
Indies, being induced to hastily re-embark on seeing at night
innumerable lights moving about, which they supposed were Spaniards
approaching to defend the shore.