The glowing beetle and the
I must admit that at one time I felt just like Gulliver in Lilliput. It was after a few glasses of rum during a party in
a very exotic, tropical country. During the dry season parties are held outside, and once outside the city, often there is nothing but jungle. So as I stepped a few steps out into the bushes, I looked down at my feet, and what did I see? Very clearly, racing along the main artery of a fallen palm leaf, was a miniature car, and behind him, another one. Both legally driving with their lights on, and one even looked as if he was
using blinker. It looked just like the illustration on top (unfortunately it is
not my own
Later, after I had calmly thought the whole thing through, and talked it over with the locals, it all became clear.
Obviously I saw beetles of the Pyrophorus species (most probably noctilucus - family
Elateridae). They are the largest insect (they can measure up to 4.5 cm) to make use of light signalisation and do so with the highest intensity. Although the efficiency of the bioluminescence is the same as that of other insects making use of the
luciferase enzyme, this particular beetle is slightly different. The brilliance is a result of the extremely well attuned emitted light spectrum to the
spectral sensitivity of the human eye (the emitted light is in the range of 486 -
720 nm). The intensity of the light can measure at around 1/40 candela, which allows for the reading of texts in darkness by placing the creature near the line of
text that is being read (the candela is a measure of light intensity). Supposedly poor Chinese and Japanese students studied under such lights. In the Caribbean and in Brazil, these
beetles have been put to a practical use - a few creatures were placed in specially constructed cages (as below) and the result was a portable torch that would light up a hut, or aid in a night walk.
Brazilian Lantern - a cage made from a pumpkin used to keep glowing