LIMACIDAE 



129 



given by the German naturalist Morch in 1865, but Deroceras, 

 an earlier name for the same group, proposed by the French 

 naturalist Rafinesque in 1820, must take precedence. 



Key to Species 



Upper surtace of body covered with flattened tubercles; breath- 

 ing pore with a white border agreste, p. 130 



Upper surface of body covered with prominent tubercles; breath- 

 ing pore not having a white border gracile, p, 129 



DEROCERAS GRACILE Rafinesque 



Smallest of Illinois slugs, Deroceras gracile is about an 

 inch (25 mm.) in length when in motion. Although generally 

 gray or yellowish in color, it is sometimes almost black. It is 



without color spots or markings of any kind. The mantle, which 

 is not much elevated above the general contour of the body, is 

 oval in shape. Distinct, elongated tubercles cover the back of 

 gracile. Its foot is narrow and whitish in color. The mucus 

 of this species is thin and watery. 



Deroceras gracile, which is widely distributed over Illinois, 

 is the common small slug of forests, fields and cities. In the 

 woods it may be found under loose or started bark, pieces of 

 dead tree limbs, chips, stones and almost any other kind of forest 

 debris. It appears to be solitary in habit, for usually only one 

 specimen is found under one piece of wood, although almost 

 every piece in a given area may contain one of these animals. 



It is common in towns and cities; here slimy marks, fre- 

 quently seen in the early morning hours, show that gracile has 

 been on a nocturnal hunt for food. It may do considerable 

 damage to truck gardens by eating the tender shoots of plants. 

 It is very fond of lettuce and other succulent plants of this 

 nature. If a garden is infested with these slugs, and they are 

 doing damage, they may be exterminated by fine ashes placed 

 about the plants. Contact with ashes causes the slugs to secrete 



