5 8 ENEMIES OF SLUGS AND SNAILS chap. 



gape.^ Eats also eat Vivipara, and even Limnaea, in every part 

 of the world. 



Every kind of slug and snail is eaten greedily by blackbirds, 

 thrushes, chaffinches, and in fact by many species of birds. A 

 thrush will very often have a special sacrificial stone, on which 

 he dashes the shells of Helix aspersa and nemoralis, holding 

 them by the lip with his beak, until the upper whorls are broken ; 

 heaps of empty shells will be found lying about the place of 

 slaughter. The bearded Titmouse {Parus hiarmicus) consumes 

 quantities of Succinea jputris and small Pupa, which are swallowed 

 whole and become triturated in the bird's stomach by the aid of 

 numerous angular fragments of quartz.^ 



Frogs and toads are very partial to land MoUusca. A garden 

 attached to the Laboratory of Agricultural Chemistry at Eouen 

 had been abandoned for three years to weeds and slugs. The 

 director introduced 100 toads and 90 frogs, and in less than a 

 month all the slugs were destroyed, and all kinds of vegetables 

 and flowers, whose cultivation had until then been impossible, 

 were enabled to flourish." 



Certain Coleoptera are known to prey upon Helices and 

 other land MoUusca. E(^cluz noticed, near Agde, a beetle {Staphy- 

 linus olens) attack Helix ericetorum when crawling among herb- 

 age, sticking its sharp mandibles into its head. Every time 

 the snail retreated into its shell the beetle waited patiently 

 for its reappearance, until at last the snail succumbed to the 

 repeated assaults. M. Lucas noticed, at Oran, the larva of a 

 Drilus attacking a Cyclostoma. The JDrilus stood sentinel at the 

 mouth of the shell, which was closed by the operculum, until the 

 animal began to issue forth. The Prilus then with its mandibles 

 cut the muscle which attaches the operculum to the foot, dis- 

 abling it sufficiently to prevent its being securely closed, upon 

 which it entered and took possession of the body of its defence- 

 less host, completing its metamorphosis inside the shell, after a 

 period of six weeks.* The female glow-worm {Lampyris noctihtca) 

 attacks and kills Helix nemoralis. 



Among the Clavicornia, some species of Silpha carry on a 

 determined warfare against small Helices. They seize the shell 



1 Joxirn. Trent. N. H. Soc. 1887, p. 58. - Ann. Nat. Hist. iii. 1893, pp. 238, 239. 



3 Rev. Nat. Sc. Quest, 1891, p. 261. 



* Petit de la Saussaye, Journ. de Conch, iii. p. 97 f. 



