Before, behind us, and above,
The fire-fly lights his lamp of love,
Retreating, chasing, sinking, soaring,
The darkness of the copse exploring."
Heber, ed. 1844, i. 258.
1865.—"The bushes literally swarm with fireflies, which flash out their intermittent light almost contemporaneously; the effect being that for an instant the exact outline of all the bushes stands prominently forward, as if lit up with electric sparks, and next moment all is jetty dark—darker from the momentary illumination that preceded. These flashes succeed one another every 3 or 4 seconds for about 10 minutes, when an interval of similar duration takes place; as if to allow the insects to regain their electric or phosphoric vigour."—Cameron, Our Tropical Possessions in Malayan India, 80-81.
The passage quoted from Mr. Cameron's book was read at the Entom. Soc. of London in May 1865, by the Rev. Hamlet Clarke, who added that:
"Though he was utterly unable to give an explanation of the phenomenon, he could so far corroborate Mr. Cameron as to say that he had himself witnessed this simultaneous flashing; he had a vivid recollection of a particular glen in the Organ Mountains where he had on several occasions noticed the contemporaneous exhibition of their light by numerous individuals, as if they were acting in concert."
Mr. McLachlan then suggested that this might be caused by currents of wind, which by inducing a number of the insects simultaneously to change the direction of their flight, might occasion a momentary concealment of their light.
Mr. Bates had never in his experience received the impression of any simultaneous flashing ... he regarded the contemporaneous flashing as an illusion produced probably by the swarms of insects flying among foliage, and being continually, but only momentarily, hidden behind the leaves.—Proc. Entom. Soc. of London, 1865, pp. 94-95.