4-20 
ENEMIES OE MOLLUSCA — INSECTS, ETC. 
Drilus, a coleopteron allied to the glow-worm, and also its larva, 
attacks and devours nemond'm, H. hortensis, and H. aspersa, the 
larva taking np its abode within the shell of its victim, exchanging 
its domicile when necessary by attacking a larger individual, and 
appropriating the shell, enclosing itself within it by a fibrous web 
before undergoing its metamorphoses. The beetle emerges as an 
imago in October, when the molluscs again begin to be torpid. 
The species of the genera Cychrin^, Carahus, and the families 
Sfop/zyliitlchr and Ilydropliilida’ all prey more or less eagerly upon 
snails, the attenuate head and prothorax of the Cychri enabling them 
to readily insinuate themselves within the shell of their victims ; 
the larva; of all these gi-oups are also verj" voracious, while the larva 
of the Olow-worm, which feeds almost exclusively on small mollusks, 
is believed by Fowler to derive its phosphorescent powers from this 
source. 
Ants have been observed by IMr. E. J. Lowe to ferociously attack 
and destroy snails as large as Helix aspeesii when they have ventured 
too near the nests. In one case more than a hundred empty shells 
of that species found near a large ant’s nest were considered to be 
remains of mollusks destroyed by the ants. 
Although the enemies of the mollusca are almost legion, and include 
members from almost every class of the animal kingdom and so des- 
tructive that it is marvellous that any individuals escape their numer- 
ous foes and live to perpetuate the race, yet, in addition to them, 
there are also enemies even amongst their own ranks which are scarcely 
less destructive than their more legitimate foes. 
In the British Isles although many species intermittently display 
malacovorous or cannibalistic propensities, such habits are not normal, 
but often induceil by hunger, or other e.xcitant, Ifycdinia lucida being 
perhaps the most readily addicted to gratifying its cannibalistic 
tastes. 
]\Iany foreign genera are, however, strictly and exclusively malaco- 
vorous, feeding chiefly upon the jiliytophagous species of snails. In 
South Africa the great Aerope caffra eagerly pursues and greedily 
devours the Helix cn^persa which has accidentally or purposely been 
introduced into that country, while in North America, at Charlestown, 
South Carolina, the introduced Rumina decollata is said to be exter- 
minating the Helix nemoi-alis, which was also a flourishing colony in 
that city. 
