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Garden sanitation is a valuable strategy to control pest and disease risks in a garden or landscape. While soil mites are not pests, they thrive in soil debris, and their abundance can attract other disease-causing vectors.
What Are Soil Mites?
Like it or not, your soil is home to billions of soil organisms. A handful of soil can contain a million nematodes, and a teaspoon of garden soil can have as many as 50 billion microbes.
The easiest way to group these soil organisms (soil biota) is by their relative size. Some are microscopic and are called microorganisms, so we have microbiota, meso (medium) biota, and macro (larger) biota.
The soil mites are in the mesobiota group, where the springtails join them. You can distinguish between the two; soil mites are walkers, and springtails are hoppers.
The meso- and macrobiota are often lumped together regarding functions, mainly because they differ from what the microbiota does. Microbiota is responsible for decomposition and transforming complex compounds into a bioavailable form that plants can readily use.
What Do These Tiny Mites in Plant Soil Do?
The combination of all these soil organisms is called the soil food web and is why plants grow; your soil is a living part of your garden. The alternative is inert, dead soil – like pumice or perlite.
The soil food web is divided into complex, interdependent layers or tiers of predator/prey relationships. These relationships are often mutually beneficial (symbiotic).
While soil mites aren’t directly responsible for decomposition, they break organic matter down to a size that bacteria, fungi, actinomycetes, and protozoa can decompose.
The nitrogen captured during this process is stored in the microorganism’s body, released into the soil when they die, and eaten by the soil mites.
As we’ll see later, there are tens of thousands of soil mite species, but in the soil food web, three groups are essential: the grazers, the fungivores, and the predator mites.
The grazers are the most ubiquitous and feed off plant debris. The fungivores eat fungi and help control diseases, and the predators eat smaller soil mites (population control), spider mites, and nematodes (another disease vector). Predacious soil mites are not parasitic like those found on birds and rodents.
There are still some gaps in knowledge regarding the below-ground system—it is estimated that only 1% of soil microorganism species are currently known.
And more and more studies are demonstrating just how complex the soil food web is and how suppressing just one species has a cascading effect on other trophic levels, jeopardizing ecosystem functioning and life above ground.
We must take responsibility for these creatures that are out of sight and usually out of mind and offer many benefits. Randomly eliminating them has consequences beyond what we can imagine.
Soil Mites Identification
Some are grazers, others are predators, and some are fungivores. Some like wet areas, others like the desert, while others can handle the cold. Some work in compost piles, breaking organic material down to a size better suited to bacteria degradation.
And so it goes on, each species specializing in different ways. When things get unsuitable, soil mites move to more suitable pastures (literally). They hop on a bus and head to an environment that better serves their needs. It’s called phoresy.
Soil mites fall in the Acariformes group offering tens of thousands of genera, but four animal orders are most commonly recognized.
There are so many soil mite species that they are still being discovered and added to taxonomies. The principal soil mite actors are grouped into four, one being the most dominant species (or most ubiquitous).
- Oribatei
- Mesostigmata
- Prostigmata
- Astigmata
Orbatid Soil Mites
The Oribatei, called beetle or turtle mites, are the most common soil mites for their shell-like bodies. Oribatid mites don’t grow more than a four-hundredth of an inch (1 mm) long, so you may require a microscope to see their body details (and four pairs of legs).
Orbatid soil mites live off fungi, algae, organic matter, dead microorganisms, and dead nematodes. They’re primarily scavengers and help in composting processes.
Astigmatid Mites
The astigmata are usually found in nitrogen-rich soils, such as gardens and lawns.
Mesostigmatid Mites
The Mesostigmata are mostly predators feeding on other microorganisms.
Prostigmatid Mites
Prostigmata is a suborder of mites that have diverse feeding habits.
White Soil Mites
As mentioned above, white soil mites are oribatid soil mites. Look out for the following characteristics.
- White soil mites are usually white or light brown. Red soil mites, as we’ll see later, are generally predatory. Other colors include orange, black, yellow, pink, or green.
- Tiny at 0.01 – 0.06 inches (0.1 – 2 mm) long. Seeing a soil mite with the naked eye is challenging, but a magnifying glass will help.
- Not an insect but an arachnid (a close relative of ticks, but also spiders and scorpions)
- Soil mite nymphs have three pairs of legs (6), and adults have four pairs (like all arachnids).
- They might be seen walking on the soil’s surface but spend most of their time below it.
- Soil mites migrate, hitching a ride on beetles or other insects.
- Soil mites do not climb onto plants (if you see what looks like mites on the leaves, you could have spider mites or aphids)
- Generally not apparent as they live in the soil, but occasionally may venture to the soil surface.
- Soil mites can’t fly or jump, and most are slow-moving or sedentary. If you have a little creature that jumps, it’s probably a springtail.
- Soil mites prefer moist compost and shady or darker soil areas with little direct sunlight.
- Soil mites are beneficial insects – it’s best not to try to get rid of or harm them.
- The red two-spotted spider mite is not a soil mite (and is seldom red).
Red Soil Mites
As soon as the words ‘red’ and ‘mite’ are referenced in a sentence, most people think of the red two-spotted spider mite, but as mentioned above, the spider mite (Tetranychus urticae) isn’t a soil mite.
Differences Between Red Soil Mites and Red Two-Spotted Spider Mites
| Red Soil Mite | Red Spider Mite |
|---|---|
| Generally red | Generally light orange |
| Bigger | Hardly visible |
| Will move around alone | Always in a cluster |
| No spider webs | Spider weds |
| Feeds in nematodes, fungus gnat larvae, springtails and smaller soil mites | Meals on the underside of plant leaves. |
Red Velvet Mite
Red velvet or patio mites (Trombidiid mites) spend most of the year below ground or under cover of soil debris as predatory soil mites. In spring, adults emerge and may be seen scurrying around on patios or walls.
Red Velvet mites venture above ground as they seek insects and insect eggs to feed on. Red velvet mites lay their eggs from early spring to mid-summer that hatch in mid-fall.
Eggs require high levels of humidity to hatch. When (and if) they hatch, tiny larvae appear with three pairs of legs and start feeding on insects as external parasites. Red velvet mites are beneficial insects because they do not harm plants and neutralize leafhoppers and other pests.
Larvae feed for a week or two, detach from the host, and the emerging nymph moves into the soil. The red velvet mite goes through three instars before emerging as an adult (able to lay eggs) in year three.
During the winter, adults typically hibernate in the ground.
Are Soil Mites Bad?
There are several mites species that you want to avoid. These include those commonly found on birds (fowl mites) and rodents (rodents). Fortunately, these have a short life cycle (10 to 12 days)
Soil mites live much longer and are not parasitic for hemoglobin, though they feed on garden pests. Soil mites are essential for soil health, plant resilience, and pathogen control.
Of course, with names like the American House-Dust Mite, and the Itch mite, there’s no wonder we have an aversion to anything to do with mites. Maybe we should rename soil mites to benevolent soil bugs (though I’m unsure what the rest of the arachnid species will think).
Beneficial Soil Mites
The value of soil mites to soil health cannot be overstated. They aid in the natural decomposition of organic matter, breaking down decaying organic debris and converting it into energy and nutrients for plants and other species that rely on the soil.
Mites in Garden Soil
Soil mites also ingest dead bacteria, fungi, and dangerous soil-dwelling animals, which are then excreted as nutrient-rich excretions back into the soil. Soil mites protect plants from fungal disease and insect infestations by devouring potentially harmful pathogens and pests.
Garden Sanitation Practices for Soil Mites
Soil mites thrive on plant debris, as do many disease organisms, and plant debris can also harbor residues of previous infections.
Many disease-causing organisms survive on infected branches, leaves, or fruits from one season to the next.
If diseased leaves are not removed and thrown away when they fall to the ground beneath an affected plant, they will re-infect the plant the following growing season with bacteria or fungus spores.
The pressure of the disease and debris removal from sick plants reduces the following season.
Numerous insects overwinter as eggs on plants they attacked the previous summer or surrounding plant debris, such as iris borers or common stalk borers, which do so on the leaves of plants they previously attacked (overwinter as eggs on nearby grass stems or weeds).
Soil Mites Sanitation Treatment
Sanitation is vital for reducing disease and insect pressure yearly in your garden or landscape. Essential steps include the following.
- Rake up and discard or burn all debris beneath infected plants each fall, including leaves and fruit. This includes infected trees, shrubs, and ornamentals such as peonies. Rogue disease-infected plants like tomatoes or peppers in the vegetable garden and rake up as much old foliage as possible, along with all discarded fruits.
- Prune out and destroy all dead or diseased branches and twigs each spring. Dead or diseased branches can be pruned out at any time of year. If you suspect a disease killed the units, cuts should be made at least 4-6 inches below the margin of visible infection.
- If your tree is susceptible to fireblight or has a history of infections and you are pruning before the tree is fully dormant, clean the pruners with rubbing alcohol or a hydrogen peroxide solution between each cut—dry and oil tools after use to prevent rust.
- Do not compost this material unless you do proper hot composting to kill pathogens and weed seeds.
FAQs on Common Soil Mite Species and How to Manage Them
What are examples of soil mites?
Soil mites are arachnids that belong to the mesobiota group of soil organisms. They play essential roles in the soil food web, breaking down organic matter and controlling pest populations. Examples of soil mites include oribatid mites, astigmatid mites, mesostigmatid mites, and prostigmatid mites. Each type of mite has its own feeding habits, preferences, and characteristics. White soil mites and red soil mites are among the most common species.
How do you manage mites?
Managing mites involves identifying the type of mite and implementing appropriate control measures. For example, predatory mites can be used to control pest mites, and cultural practices like sanitation and proper watering can reduce mite populations. Pesticides can also be used but should be used judiciously and according to label instructions to avoid harming beneficial insects and the environment. Consult with a pest control expert for the best course of action.
How do you get rid of soil mites without harming plants?
It’s unnecessary to get rid of soil mites as they benefit the soil food web. However, if you have an overpopulation of soil mites, you can improve garden sanitation by removing plant debris and reducing soil moisture to interrupt breeding sites. You can also introduce predatory mites, nematodes or fungi to control soil mite populations naturally without harming plants. Avoid chemical pesticides, harming beneficial insects and disrupting the soil food web.
Soil Mites Summary
Proper garden hygiene goes a long way to controlling pests and diseases. If you have the time and inclination, start a hot compost pile to recover the sources available in plant debris. Adding compost to your garden boosts soil biology, strengthening your soil’s health and your plants’ resilience.
