If you’ve got snails climbing up the walls of your house, you probably want to know why they do this. Surely they must have a reason other than a fondness for heights? I did a little digging and put together the 9 reasons why snails climb up houses…
Snails climb up house walls to get away from predators and avoid being stood on. They also climb walls to look for food or even eat the walls. The weather has a big influence on snails, and they often climb walls as the seasons change, to cool down, to find moisture, or to escape the cold.
Some people report seeing snails crawl 6 feet high or more. And these snails aren’t always on the walls – they also climb up windows, fences, poles, and flower pot canes. Understanding why snails are looking for higher ground will help you know when to look for snails on your house and how to stop them from climbing your walls once and for all.
Snails climb walls to avoid being eaten
Most snails climb walls to get out of reach of predators that eat them on the ground, such as ground beetles, ground-feeding birds like song thrushes and turkeys, rodents, including squirrels, rats and mice, dogs, salamanders, toads, turtles, and raccoons.
Large snails, like the giant African land snail, are eaten on the ground by bigger animals such as foxes, wild boars, and cannibal snails.
In fact, studies show that almost twice as many snails survive high up in trees compared to those that stay on the ground.
Snails on walls can still be eaten by birds, but it’s much harder for birds to swoop down and catch snails on a vertical surface than a flat one like the ground. And if a bird drops a wall snail, there’s a good chance the snail will be camouflaged by the bush and growth below so the bird can’t find it again.
But being swallowed by a bird doesn’t always mean the end of the road for a snail.
Snails in a resting phase or in hibernation seal their shell with dry mucus. If a bird swallows the snail whole, the mucus plug protects the snail from the bird’s digestive enzymes. 20% of snails survive being swallowed by a bird and simply start a new life wherever the birds poop them out.
Snails climb walls so they don’t get squashed
Living on the ground can be a dangerous way of life for a snail.
Snails climb walls and stay above ground level to avoid being stood on. When something or someone stands on a snail, its shell is often crushed. The shell keeps a snail’s body moist and protects the snail from predators. If the shell gets too damaged, the snail can’t repair it and it dries out and dies.
If you see a snail without an outer shell on its back, it isn’t a snail – it’s a slug. Slugs evolved from snails over many years and learned how to live without a shell to protect them.
Snails climb walls to find food
Sometimes snails climb to find food in high up places along a wall, on a roof, or on a balcony. Depending on the snail species, it could climb up walls to eat algae, fungi, lichen, moss, bacteria, bird droppings, insects, insect eggs, debris, wood lice, or plants in hanging baskets.
You might not have any idea what the climbing snails are eating, but they can smell food that’s several feet away from them because smell is their strongest sense. Snails use their long upper feelers to see and smell the world around them, and to find food that’s difficult or even impossible for us to see.
Snails climb to eat the walls
Some snails, like the giant African land snails in Florida, enjoy eating walls. These snails climb up to eat the paint, stucco, or concrete on the walls. They usually do this when they don’t get enough calcium from food sources on the ground.
Snails get calcium by eating leafy green vegetables, such as spinach and broccoli, leaves and wood, nematodes, fungi, algae, tree and plant sap, animal droppings, animal carcasses, snail shells, bones, antlers, rocks, soil, and paper.
Manufacturers add calcium chloride to cement to make it strong and set quickly. Calcium carbonate, or chalk, is added to paint as a pigment and filler. Limestone also contains calcium. Snails eat these substances for the calcium they provide.
But what do snails do with all this calcium?
Calcium is very important to snails. It helps them control body fluids, contract their muscle and move around, and lay eggs. But most importantly, snails need calcium to build a strong shell that protects them from predators and keeps them moist (and alive).
Snails climb walls because they want to move in
Sometimes snails climb the walls of a house looking for a way in. These snails want food and a warm, dark, damp place to live. They could enter through an open window, air vents, or gaps between your door and the floor.
If snails find a way into your home, you are most likely to see them eating your indoor plants or any mold growing in your house. The snails will spend most of their time close to a water source, like your bathroom, laundry room, or kitchen.
Snails climb walls to find moisture in the air
Snails must stay moist to survive. If their environment gets too dry, a snail can’t produce enough mucus to crawl around and its body dries out.
Snails climb the walls of houses in search of moisture. Humidity is the amount of moisture in the air. Humidity increases: after rain; when there’s a wind bringing in moisture from the sea or a nearby lake; and when there are many plants in the area that release moisture into the air with their breathing.
Moist hot air rises on warm days as it evaporates, so snails climb walls and other things to look for humid spots higher up when the temperature rises. They might also be trying to get away from a flooded ground area if there have been heavy rains.
Snails climb walls to cool down
When the ground gets too hot, snails climb up walls to cool down. The temperature on the ground is often much hotter than the temperature of the air. In fact, the ground can be 10 – 40 °F (5 – 22 °C) warmer than the air a few feet above it.
In areas with long, hot, dry summers, snails go into a summer hibernation called estivation. The snails climb a wall to a point where they are happy, then they seal their shell with a mucus plug. The plug dries and keeps the snail moist inside the shell. The plug also keeps the snail attached to the wall while it sleeps.
The snail withdraws deep into its shell, leaving a pocket of air between the snail’s body and the hot surface. The air pocket insulates the snail and helps to keep it cool.
Snails can estivate for days, weeks, months, or even years before waking up and coming out of their shell. These are important periods of rest for snails, and when the snail wakes up it often has a growth spurt.
Snails climb walls to hibernate
In areas with very cold winters, snails climb walls to find a warm spot to hibernate. They often do this in groups. On winter nights, the ground releases the heat it caught during the day into the air. This makes the soil several degrees cooler than the air above it, where the snails are asleep.
Hibernation is one of the ways that some snail species survive the cold. Click here to read all about snail hibernation and what non-hibernating snails do.
When the snails have chosen a suitable spot on a wall to hibernate, they plug their shells closed with mucus that dries out. This mucus plug keeps the snails safe and warm inside their shell during winter.
Snails climb up walls to die
Sometimes snails climb the wall of a house to die. Scientists cannot agree on the reason why snails do this, but they think it is either because the snails are infected with a fungal disease or they want to warn other snails of danger in the area.
According to a Leading Britain’s Conversation correspondent, snails climb a wall to die when they are infected with a fungal disease. The disease makes the snails want to climb up something before they die. After death, fungal spores are released and spread through the air.
Another theory is that snails climb walls when they have taken in poison or have an infection. The snails climb to a higher point before dying and giving off a chemical scent for other snails to smell. The higher point helps the scent spread further. When other snails get this scent, they know that there is danger or disease in the area.
How to stop snails from climbing your walls
It can be frustrating or worrying when you have snails climbing up the walls of your house, never mind the snail poop they leave behind as they go.
Below are the best tips and products from Amazon (with links) to try if you need to stop snails from climbing your walls:
- Scatter these pet and wildlife friendly snail bait pellets along the bottom of the walls around your house. Iron phosphate baits like this one are safer to use and better for the environment than those made with metaldehyde. The bait takes 3 – 6 days to kill the snails, so they might still get a way up the wall before dying and falling off. But at least they won’t poison any birds or scavengers that eat them when they’re dead.
- If you have time, check your wall daily and simply pick off any snails you see crawling up. The best time to look for snails is after sunset and after rainfall. Throw the snails on the ground and stand on them or crush them with a rock. An alternative is to throw them into a bucket of soapy water to drown them.
- To stop snails from getting up your wall, mix this 100% petroleum jelly with a lot of table salt. Apply a thick strip of this mixture near the bottom of the wall. Snails will struggle to cross the sticky strip and if they try, the salt should quickly dehydrate and kill them.
- Snails can’t cross copper because it reacts with their mucus and gives them a small electric shock. Apply a strip of this copper flashing along the bottom of the wall that snails like to climb, to stop them from ever getting onto your wall.
- To stop snails from getting into your home after climbing your walls, keep all windows closed when snails are active and use a draft stopper to seal the gap between your doors and the floor.