510 THE INSECT WORLD. 



spontaneously or under the influence of artificial excitement. Somf 

 chemical experiments have been made to ascertain the nature or tht 

 composition of the humour which produces this strange effect ; bui 

 up to this moment, they have only enabled us to discover that th( 

 luminous action is more powerful in oxygen, and ceases in gasej 

 incapable of supporting combustion. In the most common species 

 the Lampyris nodiliica^ or glow-worm, the phosphorescence is of i 

 greenish tint : it assumes at certain moments the brightness of white 

 hot coal. 



The females have no wings, while the males have them, and 

 possess very well-developed elytra. The females resemble the 

 larvae much, only they have the head more conspicuous, and th( 

 thorax buckler-shaped, like the male. The larvae feed on smal 

 molluscs, hiding in the snails' shells, after having devoured the 

 inhabitant. They also possess the phosphorescent property in a lesi 

 degree than the adult females. The female pupa resembles tlu 

 larva , the pupa of the male, on the contrary, has the wings foldec 

 back under a thin skin. The perfect insect appears towards th( 

 autumn. 



The Glow-worm {Lampyris jwdiluca^ Fig. 550) is of a brownisl 

 yellow. It is common in England. In a kindred species, th( 

 Luciola Italica, the two sexes are winged, of a tawny-brown, anc 

 equally phosphorescent. They are met with in great numbers ir 

 Italy, and the lawns are covered with them. Other insects of thi: 

 family are without the faculty of emitting light ; as, for example, th( 

 genus Lycus, of brilliant colours, which are met with in Africa anc 

 India. One of the finest is the Lycus latissifmis. 



Drilus is another genus, comprising insects of very singula: 

 habits. The type is the Drilus flavescens. The male — a quarter 

 an inch long, black and hairy, with elytra of a testaceous yellow, am 

 with pectinated antennae — for a long time was alone known. Th( 

 female — from ten to fifteen times as large, without wings and elytra 

 of a yellowish brown — was not discovered till much later, having 

 apparently nothing in common with the male in shape or colour 

 The metamorphoses of these curious insects are now perfectly under 

 stood. Mielzinsky, a Polish naturalist established at Gene^-" 

 found the Drilus in the larva state in the shell of the ILelix neniorii 

 These larvae devour the snail whose dwelling they occupy, as do tin 

 larvae of the Lampyris. Mielzinsky saw them emerge, but obtainecl 

 only females, which differed scarcely at all from the larvae from whicl 

 they proceeded. He made a separate genus of them, under th( 

 ' denomination of Cochleoctonus^ and called the species Vorax. Latt 



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