34 



ON LUMINOUS INSECTS.* 

 By Geo. H. Bowles, Montreal. 



Scattered here and there throughout the Organic world we find certain species 

 possessing the remarkable power of giving light — not the light generally associated with 

 the phenomena of combustion, but usually a mild phosphoric glowing or sometimes a 

 succession of brilliant coloured flashes. 



One of the most familiar instances of luminosity, is that which is due to the mycel- 

 ium of fungus pervading decaying substances such as wood, peat or fermenting leaves. 



The light is often seen at night in damp places in the woods and by the side of 

 lanes. It usually proceeds from old roots or stumps, the substance of which, during the 

 day, presents a whitish yellow appearance, but at night, throws forth a mellow, ghostly 

 light, quite startling when first seen. 



Besides the humble fungi, several plants in the higher groups are said to be lumin- 

 ous. The daughter of Linnaeus in 1762 noticed radiations of light proceeding from a 

 cluster of garden Nasturtiums (Tropaelum Majus). This appearance has also been 

 observed in the Marigold, Poppy, and other plants as well as in certain mosses. 



In the lower orders of the animal kingdom, luminosity is not uncommon. That 

 beautiful phenomenon, a phosphoresent sea, is generally ascribed to the presence in the 

 water of innumerable multitudes of microscopic beings termed Rhizopoda.-f As we rise 

 higher in the scale numbers of creatures are found endowed with this remarkable pro- 

 perty,; and when the class Insecta is reached, we see species provided with a luminous 

 preparation, which fully equals in proportion to size, the light given by our common 

 modes of over- coming darkness. 



It would be hardly right to overlook the Centipedes, though not true insects, as one 

 species at least is capable of diffusing a very strong light. This species, Scolopendra 

 electrica, is found in England, and is by no means uncommon. Though its light is 

 seldom seen, in consequence of its living in holes, or under clods of earth. The light 

 proceeds from the whole body, not being restricted to certain parts as in insects. Other 

 species of this genus are said to be luminous. One described by Linnaeus S. phosphora 

 is a native of Asia. 



Among the true insects the most familiar examples are our common Fire-flies, be- 

 longing to the family Lampyrida Leach. These little creatures may be seen in great num- 

 bers on warm summer evenings, especially in marshy places. The perfect beetle is soft 

 and flat, with a horuy, semi-transparent shield projecting over the head. The light- 

 producing organs are situated in the three last segments of the abdomen, and are of a 

 light sulphur colour. Patches of this colour also extend on either side of the head be- 

 neath the over-hanging Thorax. When the insect is taken in the hand a constant gleam 

 of light proceeds from the abdominal glands, whether it comes from the head too is 

 questionable. 



When on the wing the light is intermittent, flashing for a second and then being 

 extinguished, appearing again shortly in another place as the insect flies. 



The genus Photinus includes the greater number of our luminous species. The 

 females are provided with wings unlike certain foreign Lampyridce, and both sexes equally 

 possess the power of giving light. 



Phosphorescence has been noticed in the larvae of several American Fire-flies. 

 Specimens of Photuris pennsylv aniens (DeGeer) have been found to emit a brilliant light 

 from their anal segments,§ and it is not unlikely that many, if not all, of those that 



* A late article in the English Mechanic Vol. XXX, p 559, states that a fungus f Agaricus Pleurothu 

 emeriti u. e.) has been found in the Andaman Islands, the entire substance of which is luminous. The 

 specimens were quite young and scarcely fully developed. 



f One in particular, Noctiluca Miliaris. 



% Polypes, echinoderms, medusce, <L-c. Even the common earth worms are said to evolve a shining light. 

 § Canadian Entomologist, Vol. I, p. 39, and Vol. II, p. 38. 



