502 THE INSECT WORLD. 



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

 the larvae of the Lampyris. Mieczinsky saw them emerge, but 

 obtained only females, which differed scarcely at all from the 

 larvae from which they proceeded. He made a separate genus of 

 them, under the denomination of Cochleoctonus, and called the 

 species vorax. Later, Desmaret resumed these observations. He 

 provided himself, at the Veterinary College of Alfort, with a 

 number of shells of the Helix, filled with the same larvae. He 

 saw come out of them, not only Cochleoctoni, but also Dryli, 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 Drylus Jlavescens 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. 

 To change into a pupa it shuts up the entrance to the shell with 

 its old skin, and when arrived at the perfect state, quits the shell 

 which served it as a temporary dwelling. The females of the 

 Drylus Jlavescens take refuge under stones and dry leaves, or 

 crawl slowly along the ground, whilst the males, which fly with 

 great ease, are on the plants and brushwood. These insects are 

 not rare in the environs of Paris. M. H. Lucas has observed, 

 in Algeria, near to Oran, another curious species, the Drylus 

 mauritanicus. The larva of this insect lives at the expense 

 of the animal of the Cyclostoma Volzianum, which closes the 

 entrance to its shell with a covering of some calcareous sub- 

 stance. It fixes itself on the edge of the shell, with the aid 

 of its sucker, and directs its strong mandibles to the side on 

 which the snail is obliged to raise the covering, either to 

 breathe the air or to walk. In this position it has the patience 

 to wait for many days at the door. The snail puts off for 

 as long a time as he is able the fatal moment. But when, over- 

 come by hunger or nearly stifled in his prison, he decides at 

 last to open his door, the Drylus profits immediately by this 

 opportunity, and cuts the muscle which keeps back the foot of the 

 snail. The breach being made, nothing more opposes itself to 

 the entrance of the enemy. He slips in, and sets to work to 

 eat at his leisure the unfortunate inoffensive mollusc, which affords 



