354 MANUAL OF VEGETABLE-GARDEN INSECTS 



Liberal watering of i)laiits in tlie open will also have a beneficial 

 efl'ect on preventing- re(l-si)i(ler injnry. "Black Leaf 40" to- 

 bacco extract, 1 part in 1000 parts of water in which soap has 

 been dissolved at the rate of i pound to 5 gallons will also be 

 found useful in freeing the plants of the pests. The tobacco 

 extract is also effective when combined with the oil emulsions 

 or with bordeaux mixture. The mites may also be held in 

 check by dusting the plants with finely ground sulfur. 



Reference 

 Ore. Agr. Exp. Sta. Bull. 121. 1914. 



Slugs 



Slugs are closely related to snails, from which they differ in 

 having the shell reduced to a thin plate or wanting altogether. 

 The commonest species injurious to vegetables in the eastern 

 United States is the gray field slug, Agriolimax agrestis Linnaeus 



(Fig. 222) and has appar- 

 ently been introduced from 

 Europe. It is about It 

 inches in length when fully 

 Fi3. 222. — The gray field slug (X ID- extended, spindlc-shapcd in 



outline, ashy gray in color 

 mottled with darker gray. On the head are two pairs of 

 fleshy tentacles ; the upper pair is the longer and bears 

 the eyes at the tip. When at rest or when disturbed the 

 tentacles are withdrawn and the body contracts into a dull 

 gray lump. Slugs are found in cool, moist situations. During 

 the day they are hidden away under stones or boards and 

 come out to feed only at night or on damp cloudy days. 

 Their bodies are kept moist by a slimy secretion a trail 

 of which is left behind wherever they go. These glistening 

 snail tracks are often seen on boards left lying on the ground. 



