Proven and Effective Treatments for Garden Slugs and Snails
Snails and slugs (gastropods) are the most destructive pests in the garden today, have existed for millenniums, an d are the curse of gardeners. If left untreated, they can devastate many garden plants as well as whole gardens. The only difference between slugs and snails is that snails carry coiled shells on their backs while slugs don’t. Both have eyes at the tips of short stalks arising below the base of much longer, more slender tentacles – these tentacles feel what the simple eyes may not see.
The rasping mouth parts of slugs and snails are directed downward so that food can be taken from the surface over which they travel. Snails chew the edges of foliage and open the holes that slugs have made, it’s the slugs’ mouth parts that scrape away and puncture the surface of foliage causing the most damage.
And finally, their other calling card is slime. All gastropods have a single, broad, muscular, flat-bottom foot which propels them with the help of a special gland in the foot that secretes mucous, AKA slime. The sparkling silver trails they leave behind aren’t just a way of getting around. Slugs read them like Braille to find a mate and new chomping grounds. When they encounter few trails, as in our gardens, the slugs take it as a signal that there is virgin territory to be plundered. Where the matrix of slime is dense, however, it’s a warning to disperse and lay eggs where there is less competition for food and less risk of being attacked by predators.
There are many methods to control these slimy, destructive pests, some methods work better than others while some just don’t work at all. There is no one treatment that will work perfectly all the time, however being diligent and using varied methods of treatments (Integrated Pest Management), they can eventually become controlled to the point of tolerance or even eradicated.
It is always easier to get rid of a pest when you understand its’ habits and lifecycle. Take a quick look at the difference between slugs and snails.
Adults are soft-bodied, land-dwelling mollusks. Snails have coiled shells on their backs and are 1 to 1-1/2 inches (2.5 to 4 cm) long. Slugs are without shells. Garden slugs are 1/8 to 1 inch (3 to 25 mm) long (longer when stretched out); banana slugs may be up to 4 to 6 inches (10 to 15 cm) long.
Most slugs and snails are dark or light gray, tan, green, or black; some have darker spots or patterns. They leave a characteristic slimy trail of mucus behind them. Eggs are clear, oval, or round, and are laid in jelly-like masses.
Plants Affected: Any tender plant or shrub.
Damage: Both slugs and snails feed mostly on decaying plant material. They also eat soft, succulent plant tissue and leave large holes in foliage, stems, fruit, and even bulbs.
They can completely demolish seedlings and severely damage young shoots and plants. Snails, and sometimes slugs, can climb into trees and shrubs to feed. Both have higher numbers and cause most damage in wet years, and in regions with moist conditions, or high rainfall.
Adults lay egg masses in moist soil, or under rocks or containers, or garden debris. Eggs hatch in 2 to 4 weeks. Slugs grow for 5 months and up to 2 years before reaching maturity; snails take 2 years to reach maturity.
A good snail and slug management program relies on a combination of methods: eliminating shelters, creating unfavorable conditions, destroying existing colonies. Slugs and snails like shaded, moist environments and feed on decaying plant or wood material and in that sense are beneficial until the new Spring growth of succulent garden plants begin. Then they become unwanted, and destructive. You can pretty easily start eliminating these habitats by clearing boards, stones, decaying yard debris, weedy areas around tree trunks, low growing leafy branches, and dense ground covers. This allows fewer snails and slugs to survive, and those remaining congregate in the last few shelters where they can more easily be located and removed.
Compost piles are ideal breeding grounds for slugs and snails, especially slugs. Effectively removing them could be a chore (to say the least). Destroy slugs in these areas before new growth appears on succulent plants in the Spring by keeping the pile as dry as possible, using beer traps, nematodes (microscopic eelworms), or other methods we will discuss later.
Organic or safe slug bait is best! There are a great deal of control methods for snails and slugs. Some of the more popular ones are: beer traps, smooth metal deterrents such as copper (too expensive), hand picking (too much time), lures and traps (do not last long but very effective), Metaldehyde-based chemical products poison bait (too dangerous but very effective), organic baits such as Iron Phosphate (not really too safe but better than Metaldehyde), decollate predatory snails (they can take a long time to decrease the harmful snail population and will eat succulent plants, too), natural predators such as ducks or chickens (this solution will appeal only to those who live in a rural, or favorable setting), scratchy things such as sandpaper, cinders, wood ashes, diatomaceous earth, sand, and using plant repellants (mixing mint or sage in your mulch will repel slugs and snails).
Of the above mentioned control methods, I prefer organic slug bait in combination with the steps I have listed below: Iron Phosphate. This works quite well for me because it is fast, we have to treat a larger area than most, it’s safe for all, and even adds natural fertilizer! However, you have to apply it every three to four weeks during Spring, Late Summer, and through out the Fall months for it to effectively control slugs and snails.
Summary: Treatments I Like Best
OK, so you have some ammunition. All the above mentioned control methods work quite well, but we need something that will get rid of slugs and snails for a bit of time so we can enjoy other activities, too. I have tried all of the above mentioned control methods and after many years of combating theses destructive garden pests, I prefer to use a combination of control methods:
Step 1: As early in the Spring as possible, I will search out and destroy as many eggs and adults as I can find. Since slugs feed nocturnally, there will be some late night searches. However, if stumbling around with a flashlight is a bridge too far, look for slugs during the day in the drainage holes of pots, beneath stones and hunkered in long grass. If they evade your efforts, set traps. On a small scale, a classic that works brilliantly for hard-to-find small ground-dwelling slugs is to place the scooped out half-shells of grapefruits or oranges near the crowns of vulnerable plants. Come dawn, the slugs make for the damp yellow domes, as they love to chew the pith inside. Slugs also make a beeline for cardboard. Lay a sheet on the ground among long grass. Check your traps daily.
Step 2: Again, this method works well on a small scale slug control effort: I will either purchase nematodes or make my own and place the nematodes in the garden soil. This is really the best and safest method of killing slugs. You will get six weeks of control.
Step 3 (if needed): Treat again in about a month with nematodes, combined with organic Iron Phosphate bait (aka Sluggo or Escar-Go) , and place sand or crushed egg shells around the plants you wish to protect.
Step 4: During the Autumn months, repeat Steps 1, 2, and 3 for even better control the following Spring.