BAKER: FIELDBOOK OF ILLINOIS LAND SNAILS 23 



similarity between young and old helps to place the young with 

 the adults of their species. 



Careful attention to these keys should enable a student to 

 identify adult specimens of any of the species of land snails 

 found in Illinois. The keys are intended for aid in the identifi- 

 cation of the snails of Illinois only and could not be used very 

 successfully for land snails in general or for the land snails of 

 any other one state. Although in adjoining states and in similar 

 situations some of the same genera and species occur as in Illi- 

 nois, the presence of other genera and species not found in this 

 state would tend to make the keys inaccurate. 



Economic Importance of Land Snails 



Land snails are of varying importance economically. None 

 of the Illinois land snails is so large as the European edible snail, 

 Helix poynatia^ and none is eaten now, although some species at 

 one time furnished food for the American Indian. 



As food for other animals, the Illinois land snails are of 

 some value. Many birds are known to eat such small snails as 

 the pupoids and zonitoids. Salamanders and newts eat the small 

 slugs of the forest. Mice, moles, shrews and some squirrels ea t 

 the larger snails, and the broken shells are frequently found near 

 a burrow or at the base of a tree where some animal has had a 

 snail feast. 



As garden pests, several species of snails and slugs are 

 worthy of note. The little glassy zonitoid known as Zonitoides 

 arboreus often occurs in such abundance in the garden patch as to 

 do considerable damage. Slugs also live in the garden and eat 

 the succulent vegetables which are grown for the table. These 

 animals are nocturnal in habit and are seldom noticed. In the 

 daytime they may often be found beneath boards in or near the 

 garden. At least two species of large slugs, Limax maximus and 

 Limaxfla'oiis^ have been introduced into this country from Europe 

 and are found more or less abundantly in some greenhouses, 

 where they may seriously damage growing plants. In some 

 cities the large Limax maximus has escaped from the green- 

 houses and has been found in yards and nearby fields. The best 

 precaution against a visitation of these slugs is a quantity of 

 fine ashes scattered over the soil. In an effort to become free 

 from the irritating ashes, the slugs will soon exhaust themselves 

 by secreting an abundance of mucus. 



