Soil mites have been a part of microscopic soil activity for roughly 400 million years. In our gardens today, some of these mites greatly contribute to the health and vitality of our plants. Others are more predatory.
If you see white or red mites in your soil or compost bin, it’s important to identify which type they are before acting. If their presence is beneficial, eliminating them could be tragic for your garden.
But, if they’re the predatory variety, it could be equally tragic if you don’t. In this article, I’ll cover the different types of soil mites you may encounter and how to fix the problem when necessary.
- Shake Off and Remove Soil
- Re-Pot the Plants In New Soil
- Spray the Plants and Soil
- Insecticides With Pyrethrins
- Garlic Solution
- Cinnamon Solution
- Dish Soap & Starch
- Maintain Your Houseplants
What Are Soil Mites?
As one of the most abundant creatures in nature, mites range in size from a tiny .01mm in length to a relatively giant 12mm. Soil mites, in particular, are about the size of a pinhead.
These mites typically feed on decomposing plant material and other creatures that are detrimental to our plants, all while dispersing mycorrhizal fungi spores across our gardens. These fungal spores convert soil nutrients into a form our plants can absorb, thereby increasing soil fertility.
In poor, dry soil where natural food sources are sparse, soil mites may look to our plants as another option. This is why cultivating the health of both soil and plants is so important.
Several different species make up the soil mite family and, despite our trepidation, are not harmful to people or animals.
The most common type you might find is Oribatida. If you see a bunch of little white dots throughout your compost, don’t panic. You don’t have an infestation. You have high-functioning, healthy compost.
Common Soil Mite Species
Being so tiny, the world of soil mites can be mysterious and complex. Acarology, the study of these creatures, has only been around since the 1950s.
Since then, five primary soil mite varieties have been studied, each being observed consuming and processing decaying material and pests in and above the soil.
Oribatida are the most common variety found on houseplants, which I’ll discuss in more detail further on. Out in the garden, other varieties contribute to soil health and well-being in different ways.
Most thrive in moist soil and multiply as soil fertility increases. In arid environments, their numbers are far lower. Let’s look at each type more closely:
Tetranychus urticae Koch
Most often referred to as the Two-Spotted Spider Mite, this red-colored mite has international notoriety as a common pest that can wreak havoc on indoor and outdoor plants, fruits, vegetables, and herbs.
These are predominantly chlorophyll-thirsty, plant-eating pests that are most active and cause the biggest damage in hot and dry conditions. However, they are commonly seen in the soil while resting during the cooler, winter months.
Without the aid of a magnifying lens, spider mites are just tiny dots that are easily confused with thrips and aphids. Their distinguishing feature, however, is the webs that appear under leaves and in stem junctions.
A light infestation will look like pinpoint dots on foliage but they can reproduce quickly, leading to heavily infested leaves that will turn from brown to yellow before falling off completely.
Mesostigmata mites are travelers, often hitchhiking on the backs of birds, mammals, or other social insects, like honeybees.
If they happen to encounter one of these creatures that is no longer living, in keeping with their voracious appetites, they will use it for nourishment.
However, Mesostigmata mites also move quickly, making fast work of preying on and devouring other soil creatures that might otherwise target our plants.
With a camouflaged brown or beige exterior, these mites get their name from the ‘stigmata’ or holes in either side of their bodies that they use to breathe.
This type of mite is also a parasitic traveler, yet slower moving on the backs of grasshoppers and beetles.
The Prostigmata sub-order includes spider mites, velvet mites, and other pests we would legitimately want to eliminate. Their feeding habits are far more invasive, devouring live plants, earthworms, and other more preferable mite varieties with impunity.
Unlike Mesostigmata mites, Prostigmata are quite colorful, making it difficult to surprise their prey in dark soil. This creates the opportunity for balance that maintains a healthy population of more beneficial varieties.
Gamasid mites can be found in most soil types and, while not as prolific as Prostigmata, they’re definitely on the list to eliminate.
These ravenous, surface-dwelling predators don’t necessarily feed on our plants. But on microscopic soil creatures like the beneficial mites and mycorrhizal fungi that plants can’t thrive without.
The only benefit of Gasamina mites is that they also devour nematodes, which can decimate tomato plants.
With their tiny bodies having eight, six-jointed legs, each with a set of claws and suckers, I can certainly understand why early humans formed a defensive aversion to bugs.
What Is the Difference Between Soil Mites and Spider Mites?
Soil mites are related to spider mites in the way that humans are related to other primates. They have similar genetics but very different behaviors, feeding habits, and environmental contributions.
Soil mites prefer to remain in the soil where they’re better protected from predators and near food sources. This is also where they contribute to the health and vitality of our gardens in a variety of ways.
Spider mites often venture above ground in search of live plant material and other soil creatures to snack on. While this behavior keeps populations in check, it can also result in substantial plant damage.
Being soil dwellers, white mites go mostly unseen. On live plants and decaying material, spider mites are also hard to see but are evident by the silky, white webbing they leave behind.
If you see this on your plants and want to know if you have an infestation of spider mites, simply wipe the area with a white paper towel. If you see reddish-brown streaks on it, you do.
Getting Rid Of Soil Mites In Houseplants
Microbial soil activity around houseplants is different from that of outdoor plants. There’s just not enough room or access. So, unless you repot your houseplants using recycled soil, you typically won’t see soil mites on them.
If you do, though, remember that these are basically scavengers, rather than predators, and are completely harmless. They only feed on soil and/or compost elements and not your plants.
But, if their numbers grow to a point that is either visually undesirable or it just makes you feel uncomfortable to see them, there are several things you can do to remedy that.
And they all start with an understanding of why mites are on your houseplants to begin with. They may have arrived via old soil or on new plants brought into your home. But they stay because they have a consistent food source.
To remove this food source, simply repot your plants in a fresh, sterile potting mix that has no compost, wood chips, or decaying plant material in it.
Shake Off and Remove Soil
Removing a nuisance population of mites from your houseplants or outdoor containers can be done in several ways. Here are some simple steps that are proven to be the most effective and the most eco-friendly:
- Gently tap the sides of the plant pot to dislodge the soil from the interior
- Carefully remove the plant from its pot and place the root ball in a large bowl full of lukewarm water
- Soak the root ball for several minutes to avoid root shock
- Remove excess soil from the root ball with your fingers while it’s still in the bowl
- Make sure there are no remaining old leaves or stems tangled in the root ball
- Repot plant using fresh, sterile potting soil
Re-Pot the Plants In New Soil
When following the above steps to get rid of mites in the soil around your houseplants, using new potting soil right out of the bag is a must.
Now when I say “potting mix,” that means sterile topsoil, not just plain dirt. Many cheap potting mixes are cheap because they’re just dirt. Your poor plants would suffocate and rot in that because it’s too dense. So, make sure you read the label carefully.
Quality topsoil is loose and loamy and can come already loaded with additives such as coco coir, perlite, etc, to help with aeration. You can either purchase it already mixed or you can add your own soil-aerating and moisture-retaining elements. Either way, this is the best way to keep your plants happy and soil mite-free.
Spray the Plants and Soil
Another option to eliminate soil mites is by spraying with substances that are either offensive to them or will kill them.
This is actually a great follow-up treatment to use after you’ve replaced the potting soil. Just in case any were hiding on leaves or stems.
No matter which spray solution you use, spraying plants and soil together will ensure that they have nowhere to hide. It’s also important to do this outside so that mites won’t try to escape to other houseplants.
There are many DIY spray solutions being offered out there, but the ones I’ve found to be most effective are:
- A garlic solution (organic)
- A cinnamon solution (organic)
- Dish soap and starch (non-organic)
- Insecticides with Pyrethrin (non-organic)
Insecticides With Pyrethrins
Pyrethrin is an organic compound extracted from chrysanthemum flowers that affects the central nervous system of insects and mites on contact.
While this compound, by itself, is considered organic, the insecticides that commonly contain it are not. So, caution and outdoor use only are recommended.
This effective combination of insecticidal elements and botanicals will mortally offend any of the mite varieties we’ve discussed, including those dreaded spider mites, and lasts for several weeks.
This effective garlic “tea” contains natural sulfur compounds that are toxic to most garden pests, including soil and spider mites. One treatment lasts for up to two weeks and repels pests for up to a month.
- Soak 3-4 large garlic cloves in 4 liters (1 gallon) of water and allow this to steep for 4 days.
- Dilute steeped mixture with 2 additional liters of clean water.
- Spray diluted mixture directly on soil, stems and leaves.
Cinnamon is toxic to mites and flies. This solution probably won’t kill them but, the moment they smell it, they’ll bolt. I recommend applying this solution outside so that pests don’t end up simply moving from plant to plant.
- Mix a ratio of 1 tsp of cinnamon to 4 cups of water
- Allow the cinnamon to settle, the mix thoroughly
- Either water your plants with this mixture or apply it as a foliar spray
Dish Soap & Starch
This combination is thought to disrupt the cell membranes of insects while removing protective waxes that cover their bodies, resulting in lethal dehydration. While research continues, its effectiveness is clearly evident.
- Whisk 4 drops of grease-cutting dish soap into 5 tbsp of laundry starch
- Then, dilute this mixture in 1 liter of water
- Spray ONLY the soil around the base of plants
- Wipe off any solution that gets on stems and leaves
Maintain Your Houseplants
It’s important to maintain your houseplants in a way that will help prevent future pest issues. Incorporating the following steps into your normal houseplant care regimen will contribute to healthy plants and soil that aren’t attracted to soil or spider mites.
- Make a habit of removing leaves or other plant material that has fallen onto the soil below. These decaying bits are perfect mite food and ideal breeding grounds.
- Maintain a consistent, even humidity level for optimal plant health. Spider mites thrive in high humidity with low air circulation.
- Occasionally wipe down your plants. Mites are attracted to bits of leaves and stems where dust build-up has caused browning.
- Avoid overwatering. Overly moist soil is very attractive to mites and fungus gnats.
Are Soil Mites Harmful?
The short answer is that soil mites, by themselves, are not harmful to people or pets. This includes the scary-sounding varieties we covered.
Many soil mite varieties are actually quite beneficial when it comes to soil fertility and plant health. But the conversation becomes a little more complex when their location is thrown in.
Outside, there lives a grand menagerie of creepy-crawlies. Everything from mites to pollinating bees to butterflies and dragonflies. All contribute to the living, breathing ecosystem that our gardens are.
While helping our plants grow and thrive, mites can become an aesthetic nuisance. If there are no predators to keep their numbers in check, they’ll venture beyond plant containers and vegetable beds, crawling all over porches, patios, garden furniture, and the like in search of new food sources and places to lay their eggs. This is when action to reduce their numbers may be necessary.
If their numbers grow indoors, on houseplants, the health and well-being of those living around them need to be considered.
What Diseases Do Soil Mites Carry?
White mites in soil are considered completely benign. Being soil-dwellers (unless their numbers get out of hand), mites rarely come in contact with people or pets and are not known to carry virulent contagions or diseases.
However, soil mites have been found to act as hosts for tapeworm eggs. Tapeworms pass through infected animals to the soil through fecal matter. If people come in contact with food or water associated with that soil, they too risk infection.
Keeping potentially infected pets or livestock separate from edible plants in your garden will minimize this risk significantly, as well as only using fresh topsoil for repotting houseplants rather than outdoor ground soil.
There have also been reports of minor skin and sinus irritations associated with an excessive presence of mites in the home.
Do Soil Mites Bite?
While working the soil and tending to plants in the garden, we are often unaware of just how close we are to many microscopic soil inhabitants.
While there is no evidence of soil mites seeking to bite or otherwise attack people or pets, that’s not to say they don’t bite at all.
Occasionally, one or two of these soil inhabitants may end up on your skin. If they can’t find a safe way off and start to feel threatened, they may bite as a defensive maneuver.
In most cases, these events cause only minor skin irritations that do not require medical attention.
Are Soil Mites In Compost A Problem?
Healthy compost bins are diverse ecosystems that mimic the same natural recycling process found in the wild. A living organism is made of millions of smaller ones, like insects and bacteria, all working to benefit and enhance the decomposition of garden and kitchen waste while feasting at the same time.
One of those organisms is the white soil mite. The decomposition properties of compost make it a favorite hangout for mites.
As the second-most abundant invertebrate found in compost, you may see tiny white bugs slowly moving around your compost bin.
But, even in large numbers, mites are not a problem in compost bins. They actually help turn everything you put in your bin into garden gold a lot faster. Once you put that compost in the garden, other soil critters will cut large soil mite populations down pretty quickly.
Round Up: How to Get Rid of White Mites in Soil
As we’ve seen, getting rid of white mites in the soil is fairly simple. In houseplants, replacing old soil with fresh and spraying effective mixtures on both indoor and outdoor plants can ward them off.
But, before you get rid of them, consider whether or not you should. Are you getting rid of them because they’re truly a detriment to your plants? Or because you simply don’t like bugs?
There are certainly mite varieties in our gardens that can potentially do more harm than good. In this case, removal is a must.
Simple, white soil mites contribute to the decomposition of matter in our compost bins, allowing us access to some of the most nutrient-rich, organic materials around, much faster.
They also spread beneficial mycorrhizal fungi spores around our gardens, more efficiently distributing nutrients for all of our plants.