Observations on the habits and natural surroundings of insects made during the 'Skeat expedition' to the Malay peninsula, 1899-1900 / by Nelson Annandale.
- Nelson Annandale
- Date:
- 1900
Licence: In copyright
Credit: Observations on the habits and natural surroundings of insects made during the 'Skeat expedition' to the Malay peninsula, 1899-1900 / by Nelson Annandale. Source: Wellcome Collection.
Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.
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![pool that we discovered that the light proceeded from beetle larv*, which were clinging, dorsal surface downwards, to the floating fronds of a small cryptogam. The luminous points were blue in colour and very hrilliant, though small. They did not flicker like the lights of the fire-flies which flitted in hundreds over the surface of the marsh, and when they were extinguished they died away gradually. In the pool they did not change their position, but t^hey became sometimes brighter and sometimes less bright slowly, occasionally dying out entirely for no apparent cause. When the larva was taken out of the water, its luminosity disappeared, and did not reappear until it had been restored to its habitual element for some minutes. The light of some specimens which were placed with water and weeds in a glass jar, and brought near a lamp after they had recovered from their capture sufficiently to shine again, went out. After a longer or shorter interval of rest near the lamp, on different trials, it reappeared again. Poking them with a twig sometimes caused them to shine more brightly, but more often to become entirely dark. If several individuals were in a bottle and one of them became brilliant from any cause, the others followed suit after a few seconds. A specimen which was put into corrosive solution ceased to be luminous, but after about a quarter of an hour became exceptionally bright. It was then transferred to a weak solution of formalin ; whereupon its light went out finally, taking several seconds to disappear. During the day I was unable to find any of the larvae on the surface of the pool; but the captive specimens had deserted the floating weeds before morning, and were crawling slowly on the bottom of the jar. I did not see them feed, though the water in the jar was full of small animals of different sorts—Copepods, Protozoa, and water-mites. Nor, while I was watching them, did the larv30 ever come to the surface to take in air or to breathe. I can find no special respiratory organs in my specimens: when alive no part of the body was silvery in appearance under water. Remarks.—The question of luminosity is one even more enigmatical than that of the sounds produced by insects. It is a phenomenon which is manifested right down among the Protozoa, and even in the border-land between the two great kingdoms ; it reaches its highest development among some of the Lampyridce. In the Westmann Isles I have seen a whole village accidentally lighted up by the action of putrefactive bacteria in cods’ heads hanging to dry on the walls of the gardens; and a dead shark upon the shore was visible on the darkest night from the same cause to the distance of half a mile. Noctiluca and other marine animals— coelenterates, crustaceans, tunicates, &c.—produce even more astonishing luminescent effects. It is not apparent what is the object of this display among these forms; though possibly in the case of the Medusae it may serve as a lure for prey, as it appears to do among certain deep-sea fishes. Among the insects and Myriapoda the purpose of luminescence is also obscure h It ^ See Dubois, Bull. Soc. Zool. France, “ Les Elat6rides luraineux ” (1886), &c. [27]](https://iiif.wellcomecollection.org/image/b22406451_0031.jp2/full/800%2C/0/default.jpg)
