Slugs and Snails Pest Note

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Slugs and Snails - What are they?

Slugs and snails are molluscs, as are oysters and clams. They are similar in structure except that the snail is protected by a hard, calcareous shell that makes it less susceptible than slugs to dry conditions and sun exposure.

Slugs and snails have a soft, unsegmented body measuring 2 to 4 cm in length. The head bears one or two pairs of tentacles. The front tentacles are sensitive to odours and sometimes taste, while each of the larger back tentacles have an eye at the end. Slugs and snails are known as gastropods, which mean "stomach foot". The foot located on the abdomen, is the organ of locomotion. Slugs and snails are hermaphrodites, possessing both male and female organs.

Snails have an external shell large enough to enclose the entire animal, enabling them to survive severe conditions of drought and heat. During the day slugs and snails hide in cool dark places, under dead leaves, lumps of earth, rocks, mulch and wooden boards. When dusk falls, they emerge from their shelters in search of food. They are also more active under cloudy conditions or after a light rain. Their period of activity extends from about April to October, after which they hibernate until the following spring.

When adverse living conditions confront snails, they react by sealing the opening of the shell with a mucus sheet known as the operculum, which soon hardens to a leathery texture. The snails can then become dormant and have the ability to remain in this state for up to four years.

What can they do?

When slugs and snails invade vegetable or herb gardens, they can cause major damage, consuming up to 40 percent of their weight. Slugs and snails attack seedlings, roots, tubers and young plants, leaving large jagged holes and sticky deposits, mainly on the leaves of herbs and garden vegetables.

How can I manage them?

To prevent slugs and snails from invading vegetable gardens, it is important to remove all vegetable refuse and other sources of food as well as bricks, boards and piles of debris that are directly in contact with the soil. It is also a good idea to remove fallen leaves and to thin plants so the sun can penetrate more easily.

Slugs and Snails Removal

Hand picking is most effective in the evening, about two hours after sunset, since slugs and snails are more active at night. With the use of a flashlight, check the base of plants, the back of leaves and between the rows in the herb or vegetable garden. Use a spoon to dislodge the pests and then place them in a container of soapy water or rubbing alcohol to destroy them. Although labour intensive, one hour of hand picking will provide a noticeable reduction in snail and slug populations.

You may also trap slugs and snails by creating an ideal shelter for them in a cool dark location. Place melon or grapefruit peel or inverted flower pots in the garden, leaving space so that the pests can enter the shelter. Wooden boards or asphalt shingles covered with aluminum foil may also be used as traps. Simply place them along the plant rows with the foil side on top and nail the centre of the boards or shingles to the ground, so they are secure. During the day, slugs and snails will take shelter underneath the board or shingle to get away from the sun. Check the traps daily, and destroy any slugs and snails by placing them in a solution of soapy water or rubbing alcohol.

Place stale beer in a shallow container, to a depth of about 2.5 cm (1 inch) so that the top edge is at ground level and placed 3 metres (10 ft.) apart throughout the garden, as this will attract and drown slugs and snails. Put traps out early in the evening when feeding activity begins and empty them regularly.

Slugs and snails have natural enemies such as toads, snakes, several species of ground beetles and their larvae, wild birds and ducks, with the toad being the most important. Encourage such predators to reside in your garden to maintain a natural balance.

Barriers are an effective way to get rid of slugs and snails. Sprinkle a sufficient quantity of sand, wood ashes or baked eggshells at the base of the plants. These substances irritate the bodies of slugs and snails and deter them from climbing onto the plants to feed. Copper flashings about 5 cm high may also be installed around the borders of the garden. The copper emits a small electric charge that keeps the slugs and snails away. Strips of aluminum mosquito screening about 7.5 cm high and inserted 2.5 cm deep in the ground, can also be placed around the garden.

Products

Diatomaceous earth is a fine powder also known as silicon dioxide that consists of microorganisms found in the sea. Apply by lightly coating or dusting places where slugs and snails hide, such as in garden rows or under the leaves. As the slugs or snails crawl over the fine powder, their outer protection is scratched, causing them to dehydrate and die. Diatomaceous earth is nontoxic to humans and pets and will remain active as long as it is kept dry.

Products containing metaldehyde are the most common means of chemical control. The chemical control products containing metaldehyde are sold under several trade names in garden supply and hardware stores in the form of pellets or powders. To maximize the effectiveness of these products, they should be used in wet weather in the late afternoon or evening when slugs and snails are most active. Since only moist baits attract the pests, the soil should be damp when these products are used.

Be sure to follow label directions to ensure the safety and efficacy of these products.

Caution: Chemicals should not be used on the foliage and edible parts of garden vegetables. Care must be taken to ensure that bait formulations are inaccessible to domestic animals, since they could cause poisoning.

Responsible Pesticide Use

Before Purchasing a Pesticide

• Identify the pest correctly.
• Use physical control methods and alternatives to pesticides.
• Read the label directions and safety precautions before buying the product. The label must include the name of the pest to be controlled and the treatment location (e.g. indoor, outdoor, garden uses, pet treatment).
• Purchase only the quantity of product needed for the treatment.
• Consider hiring a licensed pest control operator.

Using a Pesticide

• Carefully read all label instructions and precautions before using pesticides.
• Do not drink, eat or smoke while applying pesticides.
• Persons and pets should vacate the area during treatment. Cover or remove quaria.
• If kitchen area is to be treated, cover or remove food, dishes and utensils.

After Using a Pesticide

• Always wash your hands thoroughly after handling any pesticide product.
• Do not permit persons or pets to contact treated surfaces until residue has dried completely.
• Provide adequate ventilation of treated areas after use.
• Wipe clean all surfaces that come in direct contact with food, such as counters, tables and stovetops, including indoor and outdoor surfaces.
• Always store pesticides out of reach of children and pets and away from food and beverages.

Accidental Poisoning

• Call a poison control centre immediately and seek medical attention.
• Take the pesticide container or label with you to the emergency facility or physician.
• Follow first aid statements on the label.
• In case of accidental poisoning of pets seek veterinary attention immediately.
• Report pesticide incidents to manufacturers (phone number on label). They are required to send them to Health Canada.

Disposing of Pesticides

• Do not reuse empty pesticide containers. Wrap and dispose of in household garbage.
• Follow the product label instructions or contact provincial authorities for disposal of pesticides.

Note:

• These are general recommendations.
• Consult the label for specific instructions.
• When in doubt, contact a professional.