COLEOPTERA. 499 
worms. I¢ is to this group that the Lampyris noctiluca, or glow- 
worm, which one sees shining during summer nights on grass 
and bushes, belongs. It has the power of making this natural 
torch shine or disappear at will. 
The luminous properties with which these insects are endowed 
have for their object to reveal their presence to the opposite sex, 
for the females alone possess these properties. In the same way 
as sounds or odours exhaling from some-insects attract the one 
towards the other sex, so with the Lampyris a phosphorescent 
light shows the females to the males. The seat of the phos- 
phorescent substance varies according to the species. It exists 
generally under the three last rings of the abdomen, and the light 
is produced by the slow combustion of a peculiar secretion. It 
has been stated that it is evolved quickly when the animal con- 
tracts its muscles, either spontaneously or under the influence of 
artificial excitement. Some chemical experiments have been made 
to ascertain the nature or the composition of the humour which 
produces this strange effect; but, up to this moment, they have 
only enabled us to discover that the luminous action is more 
powerful in oxygen, and ceases in gases incapable of supporting 
combustion. In the most common species, the Lampyris noc- 
tiluca, or Glow-worm, the phosphorescence is of a 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 
larvee much, only they have the head more conspicuous, and the 
thorax buckler-shaped, like the male. The larvee feed on small 
molluscs, hiding in the snails’ shells after having devoured the 
inhabitant. They also possess the phosphorescent property in a 
less degree than the adult females. The female pupa resembles 
the larva; the pupa of the male, on the contrary, has the wings 
folded back under a thin skin. The perfect insect appears towards 
the autumn. 
The Glow-worm (Lampyris noctiluca, Fig. 548) is of a brownish 
yellow. It is common in England. In a kindred species, the 
Luciola Italica, the two sexes are winged, of a tawny-brown, 
and equally phosphorescent. They are met with in great 
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