500 THE INSECT WORLD. 
numbers in Italy, and the lawns are covered with them. Other 
insects of this family are without the faculty of emitting light ; 
—e 

Fig. 548.—Lampyris noctiluca (male and female).* 
as, for example, the genus Lycus, of brilliant colours, which are 
met with in Africa and India. One of the finest is the Lycus 
latissimus. 
Drilus is another genus, comprising insects of very singular 
habits. The type is the Drilus favescens. The male—a quarter 
of an inch long, black and hairy, with elytra of a testaceous 
yellow, and with pectinated antennse—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 colour. 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 nemoralis. These larvee devour the snail 
whose dwelling they occupy, as do the larve of the Lampyris. 
Mielzinsky saw them emerge, but obtained only females, which 
differed scarcely at all from the larvee from which they proceeded. 
He made a separate genus of them, under the denomination of 
Cochleoctonus, and called the species Vorax. Later, Desmarest 
resumed these observations. He provided himself, at the 
Veterinary College of Alfort, with a number of shells of the 
Helix, filled with the same larve. He saw come out of them, 
not only Cochleoctoni, but also Drili, and he watched their 
coupling. It was then proved, by this unanswerable argument, 
that these two insects, so unlike each other, belong to the same 
species. 
The larva of the Drilus flavescens fixes itself upon the shell of 
the snail by a sort of sucker, like a leech. Little by little, it slips 
in between the mollusc and its house, and devours it entirely. 
