650 



Slugs and Snails. 



[FEB., 



connection, but Mr. Theobald, who has made a special study 

 of the pith moth, suggests that a poisonous spray applied 

 immediately after the gathering of the fruit might kill many 

 of the young larvae, which are said to feed on the leaves of 

 apple trees in the autumn. 



William E. Bear. 



INJURIOUS AND BENEFICIAL SLUGS AND 

 SNAILS.— II. 



Snails (Helicidce) do not do so much harm in the field as 

 slugs, but now and again they attack young wheat to a serious 

 extent. Snail attacks mostly seem to occur along " Down- 

 sides." In gardens, however, much harm is often done by these 

 mollusca, not only to flowers and choice vegetables but also to 

 strawberries. As they feed entirely above-ground, they can 

 be much more easily destroyed than the slugs. All the chief 

 injurious snails belong to the genus Helix, and have a large 

 shell, whorled in form, with a large opening into which the snail 

 can entirely withdraw its body. The opening or mouth can be 

 closed with a hardened plate formed by the foot of the mollusc, 

 called the epiphragm. This epiphragm is particularly well de- 

 veloped in the common garden snail {Helix aspersa), which, 

 during the winter, withdraws into its shell and closes it 

 with a brown horny plate. Many of these snails collect 

 together in a mass, and become united to one another's shells 

 by these horny structures. Two snails thus united are shown 

 in the plate. 



Almost every wood and hedge, field and garden yields one or 

 more species of Helix. Some are partial to the sand dunes 

 near the sea, others to Downs, or to water-courses and damp 

 places. Like slugs, they are mainly crepuscular and nocturnal, 

 but may appear in damp weather and after showers during 

 daylight. This has given rise to the popular idea that snails 

 come in rain clouds. 



The following snails have been brought to my notice as being 

 injurious. 



