ORDER V. COLEOPTERA.—THE GLOW-WORM. 283 
the slow combustion of a peculiar secretion. It has been stated that it is 
evolved quickly when the animal contracts 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 humor 
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 com- 
mon species, the .Voctcluca, 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 larva much, only they 
have the head more conspicuous, and the thorax buckler-shaped, like the 
male. The larve feed on small mollusks, hiding in the snail’s shell after 
having devoured the inhabitant. They also possess the phosphorescent 
property in a less degree than the adult females. The female pupa resem- 
bles 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. 
Phe Glow-worm (ZL. noctiluca) is of a brownish-yellow. It is a common 
insect. In a kindred species, the Luctola Italica, the two sexes are winged, 
of a tawny-brown, and equally phosphorescent. They are met with in 
great numbers in Italy, and the lawns are covered with them. Other in- 
sects of this family are without the faculty of emitting light; as, for exam- 
ple, the genus Lycus, of brilliant colors, which is met with in Africa and 
India. One of the finest is the Z. latissimus. 
Drilus is another genus, comprising insects of very singular habits. The 
type is the D. flavescens. The male, —a quarter of an inch long, black 
and hairy, with elytra of a testaceous yellow, and with pectinated anten- 
ne, — for a long time, was alone known. ‘The 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 color. The metamorphoses of these curious insects are 
now perfectly understood. Mielzinsky, a Polish naturalist established at 
Geneva, found the Drilus in the larva state in the shell of the Helix nemo- 
ralis. These lary devour the snail whose dwelling they occupy, as do the 
larvee of the Lampyris. Mielzinsky saw them emerge, but obtained only 
females, which differed scarcely at all from the larye from which they 
proceeded. 
Prinus. — The Ptiniores are all curious little insects. When touched, 
they counterfeit death by lowering the head, enclosing their antenne, and 
contracting their feet, in which position they remain some time. Their 
larv are very injurious. Many of the species inhabit the interior of our 
