good repellents but are usually not fatal to mature snails and slugs. They 
are, however, toxic to young snails. Most chemicals listed above are poi- 
sonous to humans and livestocks (note precautions below). 
The discovery of metaldehyde as a slug killer in 1934 has provided the most 
important chemical weapon against land snails and slugs known today, but it 
still is not always 100 percent effective. It may be used as a bait (a 3 to 6 
percent mixture with wheat bran, cornmeal, or similar material is most 
common); as a dust (15-percent metaldehyde by weight); or as a liquid 
spray (20-percent metaldehyde by volume). Metaldehyde is often used in 
combination with calcium arsenate or sodium fluorosilicate to increase its 
effectiveness. 
Precautions: Metaldehyde, calcium arsenate, and chlordane are 
poisons, but with care they may be handled safely. Wash your 
hands and all utensils and tools promptly and thoroughly after 
applying baits. Store baits in closed containers in a place where 
they cannot be mistaken for food and where children, pets, or 
farm animals cannot reach them. See that the containers are 
properly labeled, 
Do not apply metaldehyde dusts or sprays to vege- 
table crops. 
Protective barrier rings of coal tar, soot, ash, lime, salt, and other sub- 
stances are often used (sometimes carbolated, phenylated, or kerosenated) 
to keep snails and slugs from valuable plants. Since some of these are also 
capable of killing vegetation or injuring the soil they should be used with 
caution, Lime, salt, soot, ash, and similar substances act as dehydrators, 
causing slugs and snails to secrete lime so copiously that they dry out and die. 
Physical Control: 
Physical control involves active search for the pests and hand-picking or 
crushing them as they are found. Such measures are often impractical but 
in many places have proven to be the only satisfactory method of keeping 
down giant African snail (Achatina fulica) populations. 
Cultural Control: 

Cultural methods are often of very definite value. This involves destroying 
habitats or hiding places of the snails or slugs by clearing underbrush, 
elimination of refuse piles, loose boards, and stones. Burning heavily in- 
fested areas has been successfully employed in California. 
