Most gardeners are aware of the many pests that plague their flowers and vegetables during the growing season. However, one pest is annoyingly elusive and leaves little silver trails of slime behind hole-punched leaves. Slugs! Where the heck do they come from and why are they out at night?
Slugs prefer the cool, moist conditions of night and will use a variety of places to hide during the day. They typically hide in crevices, damp basements, under leaf litter, beneath un-trimmed plants/bushes, under old boards, beneath wet stones, and under any item that provides cool, shady conditions.
Slugs can cause some serious damage to plants under the right conditions. Read on to discover all the places slugs come from at night, and where they go!
Why Do You See Slugs More Often At Night?
Slugs are one of those pests that you often see the damage but not the critter themselves. This is because they are active almost exclusively at night!
The reason you are seeing slugs at night is that temperatures tend to drop and humidity rises at night. Additionally, slug predators are inactive at night. Turkeys, thrushes, starlings, and many other ground-foraging birds are asleep during this time.
How To Tell If You Have A Nightly Slug Problem
A single slug won’t cause you too much headache in the garden or greenhouse. However, when you have an infestation, your plants can suffer damage severe enough to ruin the crop.
A great way to keep slugs out of your garden and home is to understand where they come from and where they’re going. Once you identify their hiding place, you can either remove it or change it to be unattractive to slugs.
Slugs will only come out when conditions are cool and moist. For this reason, they are almost exclusively nocturnal feeders unless it is wet and cloudy during the day.
Since slugs are nocturnal, it can be difficult to distinguish if the damage to your plants is from slugs or some other pest.
The easiest way to tell if you have a slug problem is to look for their slime trails. During the day, they will appear as dried silver streaks on the leaves of your ornamental flowers and garden plants.
But your plants are not the only location where you can find silver slime trails. Check for these silver streaks on pavements, foundations, and even in your basement.
According to the University of Minnesota, slugs will leave irregularly shaped holes wherever they feed. Unfortunately, this can be a sign of other pests as well and is not a surefire way to identify slugs.
Once you’ve identified that you have a slug problem, it’s time to figure out just where the heck these slimy critters come from at night!
Slugs Hide In Crevices During The Day
When looking for an ideal hiding place during the day, slugs are going to gravitate toward shady, moist areas.
Slugs prefer moist areas because they are comprised mostly of water. According to Terrestrial Slugs: Biology, ecology and control, slugs may be as much as 89% water!
Water is important to slugs because they use it to produce their slime, which is necessary for their movement and therefore finding food, shelter, mates, etc.
Areas with crevices include cracks in the soil, crevices, and cracks in your basement’s foundation, and crevices in rocks and bark in shady areas.
If you’re noticing damage to your garden plants combined with a slime trail, try to locate any cracks or crevices slugs may hide in during the day, as this is likely where they’re coming from at night.
If possible, seal these cracks and crevices with caulking or wire mesh to prevent slugs from reentering during the day. Fill in soil cracks with more soil.
Slugs Come From Your Basement At Night
Basements are known for being cool and damp, a perfect haven for slugs. But can they really get inside your home?
If your basement is unfinished and is cool and damp, slugs will make themselves at home. They will be especially attracted to utility rooms that contain washing machines, laundry tubs, and wet buckets or trash cans.
Slugs may be in other areas of the house, such as the kitchen, hallways, or bathrooms, but basements have the best conditions for them.
Slugs are attracted to food, moisture, and cool temperatures. If you have pet food down on the floor, it might attract slugs inside as well.
Look for a combination of cool temperatures, moisture, and smooth surfaces. Slugs cannot cross rough surfaces, so if your basement is carpeted, it’s unlikely to have slugs.
Leaf Litter And Mulch Harbor Slugs During The Night
Mulch is an excellent source to help retain moisture in the soil. It’s why many homeowners place it around their trees and other landscaping plants that require lots of moisture.
Unfortunately, mulch can attract and harbor slugs as well. Heavy leaf litter is an organic source of mulch that will retain moisture underneath it, making it a slug attractant as well.
According to the University of Kentucky, plant debris can also be where slugs are coming from at night.
If you leave pulled weeds, grass clippings, or prunings lying around, slugs can use this to keep cool and wet during the day.
Slugs Come From Beneath Groundcover Plants At Night
Groundcover plants are typically trailing or vining plants that grow along the ground. They’re useful to cover areas where other plants won’t grow, such as in partial to full shade.
The conditions under groundcover plants make it a great hiding place for slugs during the day. At night, slugs will emerge from these groundcover plants and make their way to your garden.
Some popular groundcover plants that may harbor slugs include:
- Dead Nettle
- Creeping Juniper
- Golden Moneywort
- Lily of the Valley
- Wild Ginger
Watch out for these plants, or any other groundcover plant, as slugs will use them as safe havens during the day and emerge from them at night.
Slugs Hide Under Old Boards For Shetler
If you’re someone who enjoys creating gardens and landscapes around your yard, it’s no surprise to find old boards, plywood, unused pots, and tools lying around the yard.
Discarded boards and flowerpots can create an environment similar to a groundcover plant underneath them: cool, moist, and shady. Slugs will use these materials to keep moist and cool during the day and emerge from them at night to attack your garden plants.
Luckily, this is an easy fix by stacking old boards neatly, discarding unused flower pots, or else storing them somewhere dry, and putting away unused tools.
Slugs Emerge From Under Stones At Night
Have you ever kicked over a stone and been surprised to find a worm or salamander there? It may be a hot day, but these water-loving critters are chilling in air-conditioning under a stone!
Slugs can also be found under stones during the day and emerging from them at night. The space under rocks stays cool, and the rock helps retain moisture in the soil after rains. The dark conditions under a stone make it even more alluring to slugs.
Stones are often used in landscaping to help control weeds and for ornamental value. If you place fabric under the stones, they are less likely to harbor slugs, but if the stones are placed directly on the soil, they will be an attractive hideout for slugs during the day.
Slugs Will Use Anything That Provides Moisture And Shade
We hit some of the biggest slug havens so far, but really, slugs will use just about anything that provides shade and moisture.
For the most part, slugs will leave bushes and trees alone, as there isn’t enough moisture or shade under them. However, there are always exceptions and certain trees that are low to the ground may harbor slugs.
Woodpiles, left-out equipment, buckets, containers, pool decks, leaky sprinklers, foundations, and stone piles can all be places where slugs are coming from at night.
If it’s wet and cool, slugs will use it.
Take a walk around your yard and try to think of places that stay cool and moist all day long. That is going to be where slugs are coming from at night.
How To Stop Slugs In The Home And Garden
It’s never fun to see these slimy, squishy creatures inside your home. It’s even worse when your garden veggies and fruits fail due to slug feeding.
Rest assured, there are plenty of options to stop slugs from wreaking havoc in your garden and sneaking into your home.
Slugs are part of the gastropod class. This is an important distinction from other garden pests because insecticides will not work on slugs since they are not insects. Instead, slugs are more closely related to clams and mussels.
When it comes to repelling and deterring slugs from your yard, you have a few options.
Avoid Moisture To Keep Away Slugs
You’re probably sick of hearing it by now, but slugs need moisture to survive. If your home and garden lack moisture, they will also lack slugs.
But how can you avoid moisture when your garden plants need water to grow?
- Water in the morning: Slugs are most active at night. If you water your garden in the morning, it will have all day to dry out, making it less attractive to slugs.
- Hand water or use drip irrigation: The use of overhead sprinklers creates a wet environment for both the soil and the plant leaves. Instead of sprinklers, consider hand-watering or using drip hoses that place the water directly into the soil instead of on the plant leaves.
- Prune: When able, prune the bottom of your plants so they are lifted off the soil. This will help improve air circulation and give the soil a bit of sun, which can help dry the area out.
Another good practice to avoid moisture is to spread your plants appropriately in the garden so they are not overlapping. This will encourage good air circulation, which will help leaves and stems dry out quickly after rain or watering.
If you have ornamental plants and flowers that need dividing every few years, be sure to keep on top of it. Plants that are too close together will provide extra shade and moisture for slugs.
Use Yeast To Get Rid Of Slugs
As funny as it sounds, yeast can be an effective tool to get rid of your slug problem. You can also simply use some yeast mixed with warm water!
Bread, your favorite drink, and other yeasty things are highly attractive to slugs. An article in the Journal of Insects found that a simple mixture of flour, yeast, and water was enough to attract slugs effectively for up to 8 days before it needed replacing.
So, why does yesast affect slugs?
Yeast is an effective slug-be-gone because the slugs are attracted to it’s scent! When they get too close to the yeast and water mixture, they’ll fall into the liquid. Slugs can’t swim, so the fall is a game ender.
To use yeast to get rid of slugs, follow these steps:
Step 1: Scope out your problem areas. Identify how many yeast traps you will need. If slugs are only affecting one or two plants, one trap will be enough. If your entire garden is affected, you will need more.
Step 2: Bury a 6-inch-deep container in the ground so the top of the container is flush with the ground. Repeat for your other traps.
Step 3: Pour a mixed solution of 1 part water and 1 part flour into the container along with 2-3 packets of yeast into the container until it is 1 inch from the top of the container for each trap.
Step 4: Check and empty the slug traps once a week. The yeast mixture will need to be replaced about every 7 to 8 days to remain an effective attractant.
Use Copper To Deter Slugs
Slugs have a tough time navigating over rough terrain. Copper isn’t necessarily rough terrain, but it gives slugs quite a shock – literally.
Copper is considered a tiny electrical fence for slugs. Studies such as the one in the Journal of Pest Management Science have confirmed that copper significantly reduces the movement of slugs.
You can use what you have, such as old copper pipes or wires, and lay them around your garden plants or flowers that you want to protect.
For potted plants, you can use copper tape such as Kraftex’s Copper Foil Tape Conductive Adhesive and tape your pots, benches, or flower beds.
This product is a good choice because it is 2 inches wide. You want a copper tape that is large enough that the slug will have its entire body over the copper tape if it tries to pass.
Thin bands of copper tape will not deter slugs. The same can be said for copper pipes or wires. They need to be thick enough to cover the whole slug when it tries to slime its way past.
Slug Granules Keep Them Away
There are commercial products available online that can eliminate slugs through certain chemicals, such as sodium ferric and iron phosphate.
They typically come in granule pellet forms that can be spread throughout the garden or in flower pots. Monterey’s Sluggo Plus is a prominent brand that is effective against slugs by using iron phosphate.
However, it should be noted that many of these types of products will be detrimental to non-target species that are beneficial to your garden. It’s recommended to use this product only if other tactics did not work or you have a severe infestation.
Always read the label on the package before use.
Use Essential Oils To Repel Slugs
Essential oils are becoming more and more popular as a natural deterrent for many pests. Luckily, there is an essential oil that works on slugs, too!
According to Oregon State University, clove bud oil is effective at controlling slugs (and snails!) in gardens and landscapes.
To use clove bud oil to repel slugs, place 10-15 drops of essential oil per cup of water into a spray bottle. Nexon Botanic’s Organic Clove Essential Oil works great.
Use the spray bottle on the base of your plants and any of the attractants we mentioned above, such as cracks and crevices in the foundation, spaces beneath bushes and groundcover plants, and anything else that provides shade and moisture during the day.
When using essential oils, it’s best to use them outdoors. Do not spray directly on edible parts of plants. Reapply your essential oil spray once a week to keep the scent strong and effective against your slimy enemy.
That’s A Wrap!
Waking up to find a bunch of holes and damage to your flowers and garden can be irritating at first and downright annoying throughout the growing season.
Slugs may be slow-moving, but they can do immense damage at night and be gone by morning. These slimy pests find safe hiding places during the day and only come out at night.
Now for a quick recap –
The 7 places slugs come from at night include:
- Cracks and crevices
- Damp basements
- Under leaf litter & mulch
- Under plants & bushes
- Under old, rotting boards
- Under stones
- Any item that provides shade, cool temperatures, and moisture
If you can eliminate these potential hiding places, slugs are less likely to hang around your yard and, therefore, less likely to damage your garden plants and flowers.
Along with eliminating their daytime hiding places, you can also use yeast traps and commercial granules. You can modify your garden so it is less humid by hand-watering and spacing your plants properly.
Another option is to use clove bud oil to deter slugs from certain plants and locations. The BEST way to keep slugs away is to combine a few of these tactics.
If the slugs are going crazy around your home and they’re resistant to your attempts to get rid of them, use our nationwide pest control finder to get in contact with a professional near you.
Radwan, M. A., & Gad, A. F. (2021, June 25). Essential oils and their components as promising approach for gastropod mollusc control: a review. Journal of Plant Diseases and Protection, 128, 923-949.
Schuder, I., Port, G., & Bennison, J. (2004, August 18). The behavioral response of slugs and snails to novel molluscicides, irritants and repellents. Pest Management Science, 60(12), 1171-1177.
South, A. (2012). Terrestrial Slugs: Biology, Ecology and Control. Springer Netherlands.
Veasey, R., Cordoba, M., Colton, A., Fujimoto, L., Dodge, C., Foley, I., Adams, G., Anderson, T., Merenz, R., Hara, A., Roda, A., Millar, J., & McDonnell, R. (2021, April 07). Fermenting Bread Dough as a Cheap, Effective, Nontoxic, and Generic Attractant for Pest Snails and Slugs. Insects, 12(4), 328.
Zack is a Nature & Wildlife specialist based in Upstate, NY, and is the founder of his Tree Journey and Pest Pointers brands. He has a vast experience with nature while living and growing up on 50+ acres of fields, woodlands, and a freshwater bass pond. Zack has encountered many pest situations over the years and has spent his time maintaining and planting over 35 species of trees since his youth with his family on their property.
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