Myriads of bright fire-flies in these wild dances meet their destiny, being entangled in opposing spiders' webs, where they hang like fairy lamps, their own light directing the path of the destroyer and assisting in their destruction.
There are many varieties of luminous insects in Ceylon.

That which affords the greatest volume of light is a large white grub about two inches in length, This is a fat, sluggish animal, whose light is far more brilliant than could be supposed to emanate from such a form.
The light of a common fire-fly will enable a person to distinguish the hour on a dial in a dark night, but the glow from the grub described will render the smallest print so legible that a page may be read with case.

I once tried the experiment of killing the grub, but the light was not extinguished with life, and by opening the tail, I squeezed out a quantity of glutinous fluid, which was so highly phosphorescent that it brilliantly illumined the page of a book which I had been reading by its light for a trial.
All phosphorescent substances require friction to produce their full volume of light; this is exemplified at sea during a calm tropical night, when the ocean sleeps in utter darkness and quietude and not a ripple disturbs the broad surface of the water.

Then the prow of the advancing steamer cuts through the dreary waste of darkness and awakens into fiery life the spray which dashes from her sides.

A broad stream of light illumines the sea in her wake, and she appears to plough up fire in her rush through the darkened water.
The simple friction of the moving mass agitates the millions of luminous animalcules contained in the water; in the same manner a fish darting through the sea is distinctly seen by the fiery course which is created by his own velocity.
All luminous insects are provided with a certain amount of phosphorescent fluid, which can be set in action at pleasure by the agitation of a number of nerves and muscles situated in the region of the fluid and especially adapted to that purpose.