Slug and snail control
Snails and slugs have been the bane of gardeners for generations. And while over time, many methods have been developed to control these slimy pests, some methods work better than others. The goal in creating this “Definitive Guide” was to show all the different ways to kill snails and slugs, or simply control them. You can choose which method, or combination of methods, will work best for you in your particular garden or situation. The snail and slug control methods listed below are not in any particular order, but all of these methods are organic, except one, (and you’ll see its drawbacks when you read it). The basic fact is that all these methods work to varying degrees, and will make it easy to implement something quickly. Won’t it be nice to have healthy, uneaten plants once again!
Quick Identification First
Before we get started, let’s take a quick look at the difference between slugs and snails which is probably apparent to you, but let’s take a quick look anyway. It is always easier to get rid of a pest when you understand it, its habits, and its lifecycle.
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.
Both slugs and snails feed mostly on decaying plant material. They also eat soft, succulent plant tissue and rasp 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.
- Life Cycle
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 up to 2 years before reaching maturity; snails take 2 years to reach maturity.
1. Hand Picking
Hand-picking and disposing of slugs and snails (including stomping on, throwing in the street, dropping in a bucket of salt water, etc.) does work, because if you gather up all the adults before they reproduce, things will get dramatically better, because the tiny ones you miss, don’t do the most damage.
You can do this by day, or go out at night with a flashlight and gather slugs by hand and drop in soapy water in a container they can’t climb out of.
|Tip: If you’re going to do this, use chopsticks or tweezers. Doing it with gloves is very cumbersome, and using your hands leaves a thick slime, so use some other device to help pick slugs off plant leaves.
|Note – A Word About Salt and Salt Water: If you wish, you can discard snails or put them in a bucket of salty water to kill them – but don’t put salt out in the garden directly on the soil, you’ll end up ruining your soil!
2. Beer or Yeast & Honey Mixture
Snails and slugs are attracted to the scent of stale beer or a mixture of yeast and honey.
- Put out a saucer filled with stale beer, or the yeast and honey mixture (listed below)
- Sink it into the ground so the top of the saucer is at ground level
- Slugs and snails will get into the mixture and drown.
Keep in mind this will only reliably kill slugs if the trap is deep enough so that slugs can’t reach over the top to get out. So in the case of slugs, use a deeper trap like a yogurt container, or a deep plastic cup. Something that is too deep for a slug to climb out of, so it drowns in the beer.
Check the container daily to make sure a frog or something else hasn’t accidentally fallen in, and also empty and refill every couple of days.
Yeast & Honey Mixture:
Now, if you normally don’t have beer around, a very effective alternative is boiling some yeast and honey in water. The proportions aren’t very critical, just mix some up.
Once that is made, continue as above. Bury a dish up to the rim in your garden and fill it with this mixture. You’d be amazed at how well this works. The snails and slugs will glide right in and drown themselves. We’ve also heard old grape juice works well, but we have never tried that.
3. Dry Dog or Cat Food
Another good food to lure snails and slugs away from your plants is to use dry dog or cat food.
- Get a tin foil pie pan and cut a few notches along the rim so that when you set it on the ground you have created a few “doors” for the snails to come in
- Pour some dry cat or dog food where you want the snails to come
- Put the tin foil pan upside down and weight it down with a rock
- Next morning, you can scoop up the snails, put them in a bag, and toss it in the trash
|Note: If you have a problem with raccoons, skunks, or opossums in your area, make sure they are not eating the food. If they are, discontinue and try another method.
4. Copper Deterrents
Snails and slugs cannot tolerate copper; it gives them a slight electrical shock on contact. Knowing this is great, but keep in mind that it creates a barrier only. It won’t kill them; it will only keep them out of an area that doesn’t already have a problem.
This can be very helpful for raised beds, trees, containers, flower pots, and other areas in your yard or garden.
After you have applied the copper to the desired area, finish by bending the exposed vertical strands outward. (see pictures)
|Note: This works only for slugs if the copper strip or mesh is wide enough so that slugs can’t raise their bodies over it. The majority of copper stripping sold in garden shops for this purpose is not wide enough to create an effective barrier, which would need to be 6 to 8 inches (15 to 20cm) wide, or the largest most destructive slugs will hump right over it without touching the copper. If need be, simply put down a double layer of banding to make sure it is wide enough.
Examples Where Copper Works Well:
Tree trunks: Apply a copper band around the base
Flower pots: Apply a copper band around flower pots and they will not cross it
For cold-frames or raised beds: Attach copper flashing to the frames
Greenhouse benches: Attach 3 inch (7.5 cm) wide copper bands around edges Now obviously, putting a copper barrier around an entire garden is not going to be practical, but it is an excellent method for protecting very sensitive seedling beds or small containers. Copper screen or copper flashing can surround a raised bed, or for small planters, copper foil (such as Snail-Barr) can be used to wrap the entire container. Shrubs can have a band of copper around the lower trunk. In order for the copper to continue to work, it needs to be cleaned periodically with vinegar or it will tarnish and no longer work.
5. Scratchy Things
Scratchy things such as crushed eggshells, sandpaper, cinders, wood ashes, and diatomaceous earth (this will need replacing if it gets wet), work well as a barrier. Again, this method will not kill the snails and slugs, but it will slow them down. Another scratchy material they don’t like to cross is sandpaper. You can make sandpaper collars to put around your plants if you have the inclination. Cut doughnuts from sheets of sandpaper, or use used sandpaper discs from orbital sanders. Cut a slit to the center of each circle, and slip the collars around the stems, laying the sandpaper discs on the ground.
6. Natural Predators
Possums, chickens, ducks, turtles, tortoises, rats, some birds, and snakes, will prey on snails and slugs. Most people that have chickens and ducks hardly ever see a slug or a snail.
7. Predatory Snails
A predatory snail called a Decollate snail (Rumina decollata) will feed on young snails and may be worth a try, but they also may nibble on young plants. It takes a little time to get an established group of Decollate snails, but many people have been pleased with the results. These snails are semi-tropical and don’t thrive in temperate or cold gardens; and in some places where they would thrive, they are banned as potentially invasive species. They are however, physically attractive snails, and when they do the work effectively for some gardeners, they should be encouraged to keep doing so. If you want to try these, make sure to avoid any kind of snail bait, organic or other, because it will affect these snails too.
8. Organic Baits
Two of the best organic snail and slug bait products on the market are Sluggo and Escar-Go which contain iron phosphate. They are safe to use around pets, humans, fish, birds, beneficial insects, and mammals. For several other organisms, including earthworms and certain ground beetles, no harmful effects are known. You can also safely use iron phosphate around food crops, ornamentals, lawns, gardens, greenhouses, and berry gardens up to the day of harvest.
Iron phosphate is an organic compound that is found naturally in the soil, and if the bait is not consumed by a slug or snail, the material breaks down into fertilizer for your soil. Iron phosphate is not volatile, and does not readily dissolve in water, which minimizes its dispersal beyond where it is applied. It is applied to the soil as a pellet that also contains bait to attract snails and slugs. When the pests eat the pellets, the iron phosphate interferes with calcium metabolism in their gut, causing the snails and slugs to stop eating almost immediately. They die 3 to 6 days later.
Iron phosphate is more effective than Metaldehyde-based chemical products (such as used by Ortho) because Metaldehyde ceases to work when it gets rained on, or if you water the garden, whereas iron phosphate remains active even with repeat wettings, for up to 2 weeks. Some people will argue that Sluggo and Escar-Go are not as cheap as Metaldehyde-based products, but this isn’t necessarily true, because iron phosphate remains active longer, so it requires less to be used to kill more slugs, so in fact it is cost-effective.
What works best is to kill the adult slug and snail population early in the year before they lay their eggs. If you do that, you will be slug and snail free for the rest of the year without further applications. The best time for long-term control is to treat the whole garden in the dampness of autumn. That way, in the spring, there will be very few adult slugs and snails to lay their eggs. Another application is useful in late winter or early spring, and again 1 month later. Three applications a year can do the trick.
How to Apply:
Iron phosphate products are used the same as other bait materials. Simply scatter the granules over the soil’s surface, (do not place in piles), where snails and slugs feed. If the ground is dry, wet it before applying bait. The soil should be moist but with little or no standing water. Once the slugs have eaten the bait, they immediately stop eating and crawl back under the plants to die. Iron phosphate is slower acting than the synthetic metaldehyde, but is active on the soil surface longer that other baits, and when ingested, the slug stops damaging your plants, which is the whole idea.
Some Basic Facts:
Sluggo and Escar-Go have a powerful lure that slugs and snails find irresistible. Repeated studies have shown that slugs and snails will eat these baits before they will eat nearby plants. Iron phosphate disposes of snails and slugs without mess. You may not see the dead slugs and snails in your garden because they often crawl away to secluded places to die. But you will notice that your plants are no longer being eaten.
Iron phosphate controls in hard-to-reach areas. because it actually lure snails and slugs from their hiding places, which provides control in any area that slugs frequent, even in mulched beds. The only thing beneficial that would be harmed by iron phosphate would be predatory, snail-eating, decollate snails (mentioned above in number 8). If a garden does have these predatory snails, do not use iron phosphate or any other bait.
9. Chemical Baits
Methaldyhde-based baits – A word of caution if you have been using a pelleted form of snail bait; it can be dangerous around pets as it looks like food to them. The finer granule type is much safer – but please be careful and read the label and use as directed.
Slug and snail baits with Metaldehyde are sufficiently toxic that such baits are not recommended for use around edible vegetables, and can be harmful to dogs, cats, and fish. Baits with Metaldehyde work differently than the organic ones with iron phosphate, and since we have already given great detail about how iron phosphate works above, let’s look at Metaldehyde.
Metaldehyde poison dehydrates the snail or slug rather rapidly if it eats the poison. That is a good thing, but slugs and snails can recover from Metaldehyde poisoning if there is rainfall, or access to wet locations, where they will not fully dehydrate and die. A slug can lose half its body weight and shrink to a third its size from Metaldehyde poisoning, or by covering it in salt, but if it can get itself to wet soil fast enough, or if it rains, it will recover. Because Metaldehyde by itself sometimes isn’t as effective as it could be, some products like Ortho Plus include carbaryl to increase its toxicity. Carbaryl kills beneficial insects and therefore should be used with caution. Another drawback is that after being dampened, Metaldehyde products no longer work, so that means every time you water, or it rains, you will need to re-apply it. Many chemical-based baits do work, but be careful how and where you apply them.
10. Coffee Grounds
The alleged method of slug control using old coffee grounds, we think, amounts to gardening folklore because we have found it doesn’t work very well. If, however, you are a person who uses this method and swears by it, by all means continue! No sense in stopping something that works for you.
11. Spray with Vinegar and Water
Mix equal parts vinegar and water. We have never tried this, but many people have sworn that spraying this mixture on snails and slugs solves the problem for them.
12. Herbal Repellent
Putting mint or sage in your mulch is reported to do a good job of repelling them. We have never tried this, but many people have sworn by using this mixture to repel slugs and snails. It won’t kill them; apparently it just acts as a barrier.
Another method found very useful is 1 part ammonia to 4 parts water in a spray bottle. We have read that the ammonia is not harmful to the plants and have found no ill effect in using it on plants. It literally dissolves the slug or snail when sprayed on the critter. There is some satisfaction in this method when you discover a precious plant chewed to pieces and the culprit is dissolving before your eyes. It is very easy to carry a spray bottle with the rest of your garden supplies and I have found it to be effective. Another recipe calls for mixing in a hand-sprayer bottle 1 1/2 cups (360 ml) ammonia, 1 Tbsp. (15 ml) Murphy’s oil soap, and 1 1/2 cups (360 ml) water. The soap helps the tonic from running off of their bodies. It is safe to over-spray any area where activity is seen. Something to keep in mind is that ammonia is not bad for your garden.
A method that works on Banana Slugs: Gather up some glass jars and put a tablespoon (15 ml) or two or three of cornmeal in each one. Lay them on their sides near the plants where the slugs are dining, making sure to provide easy entrances to the jars. They crawl inside, chow down, and die. Empty the residual mess into the trash in the morning.