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Soil mites are essential mesofauna that feeds on decaying organic matter, bacteria, fungi, and nematodes in the soil. There are tens of thousands of soil mite species, and soil mite population diversity is commonly used as a soil health indicator.
More About Soil Mites
Soil mites are tiny relatives of the spider and tick (arachnids) found worldwide in varied environments, from the poles to the equator and everywhere. A cupful of healthy soil can have as many as a hundred soil mite species and a thousand mites.
While fungi are the most abundant microbiota, mites are the leading group of mesobiota, followed by the macrobiota groups of larvae, pot worms, beetles, centipedes, millipedes, ants and spiders.
These form a critical, generally balanced soil food web with varying predator/prey relationships. Diversity is essential to keep all the cogs connecting and moving. Remove one cog, and the dependent elements of the system collapse. Diversity contributes to maintaining a system’s balance.
Why Are There so Many Mite Species?
Like humans, mites specialize. A single mite species cannot do everything that needs to be done. Each species is specialized in what it does, what it eats, and what it feeds, all enabled by a suitable environment.
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 soil mites 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.
How do Soil Mites Get Around?
There’s an article I once read on mites and their impact on soil health. The research piece explored how industrial farming techniques destroy the habitat of soil mites and, by implication, the soil mite population.
Then they did a longitudinal study on the changing soil biota of the previously intensively cultivated land as it transformed into an extensively cultivated grassland. Over time, they measured the soil mite population levels and their diversity, noting that it continued to increase, generally becoming more balanced.
Great!! But where did the additional species of arthropods come from? Which moving company moved the new soil mites species in? Phoresy, of course. Fascinating.
Soil mites hitch a ride with beetles and other fast-moving transport systems. The relationship is often symbiotic, one mutually benefiting from the other. Scientists are unsure how soil mites know where to disembark and hypothesize that some sensory indicators may exist.
Scientists are fascinated with this little creature’s ability to make a massive contribution to soil health.
How Small are Soil Mites?
Soil organisms can be divided into groups depending on their size, function, or ancestry. If we look at soil organisms’ sizes, three groups apply—micro, meso, and macro; small, medium, and large. Meso biota is bigger than microorganisms but smaller than ants (macrobiota). Soil mites are tiny organisms with diameters ranging from four-hundredth to an eightieth of an inch (0.1mm to 2mm).
The soil mite life cycle is divided into four stages: egg, larva, nymph, and adult. Eggs hatch into a larval stage, which molts into the first nymphal stage. The nymph grows into an adult in two or more iterations. Soil mites have three pairs of legs as larvae; the fourth pair evolve as the nymphs mature.
Typically, it would be best to have a microscope to see mesobiota species, though some can be observed with the naked eye (or magnifying glass). You may spot them as they move over a clean tiled surface, typically on a patio.
Types of Soil Mites
If what’s crawling across your patio tiles isn’t a tick or spider, it’s probably a soil mite. They are generally white, brown, red (predators are red), or translucent.
Mites in General
According to fossils, soil mites have been around longer than humans but only a tenth as long as fungi and bacteria, which have been around some 3.5 billion years (probably the first inhabitants).
Three primary mite families are recognized (remembering that scientists estimate that they’ve only identified about five percent of the total mite classes). These represent all creatures called mites, and not soil mites specifically.
- Opilioacariformes
- Acariformes
- Parasitiformes
Soil Mites (Acariformes)
Soil mites fall in the Acariformes group (often called Acari or oribatid mites), offering tens of thousands of genera, but four sub-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 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 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.
In the Type of Soil Mites article, I cover the types of soil mites in more detail.
Why are Soil Mites Important
The value of soil mites to soil health cannot be overstated. They are responsible for the aggregate formation, essential to saturation porosity (a soil’s ability to retain air when saturated), pathogen control, and nutrient recycling.
Healthy soils teem with micro- and macroscopic creatures collaborating to produce and sustain a vibrant, mutually beneficial ecosystem for plants. 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.
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.
Why do People Dislike Mites
Humans are generally afraid of what they don’t understand. This fear of the unknown is common to all species, a caution developed over millennia that has allowed us to survive. Hello survivor.
It doesn’t help our understanding of soil mites when the internet contains articles with bold titles like “How to Get Rid of Soil Mites” or “Mites Carry Parasites – Watch Out For Tapeworrm.”
Soil mites eat tapeworm eggs, and when a grazing herbivore eats grass with a soil mite on, it may ingest the egg that will hatch into a tapeworm. Some parts of this worm may be excreted, and the cycle begins.
But unless you eat grass, the likelihood of you ingesting a tapeworm egg hidden in the belly of a soil mite, your chances of getting a tapeworm is minimal. Soil mites cannot bite people and infect people in any way.
We also know spider mites can harm plants, but these are plant mites, not soil mites. Several mite species are plant and human pests, but these are not soil mites.
Be kind to your soil and the plants that grow in it – save a soil mite today.
Do Soil Mites Pose a Threat to Humans?
Remember we mentioned Parasitiformes earlier. Soil mites are non-parasitic. There are parasitic mite varieties (Parasitiformes), usually hosted by birds or rodents, but none of the soil mites find blood appetizing.
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 could change the name of the soil mite to the general do-gooder.
How to Support Soil Mites
The best way to support your soil biota is to make compost from your local garden waste and add it to the soil. Organic matter is vital to soil biota activity, and it has been shown that debris diversity impacts soil mite population diversity, which is a good thing.
Avoid using fungicides, as some soil mites are fungivores. If you kill one, the other suffers. Also, avoid using insecticides because the soil mite isn’t an insect (it’s an arachnid); it eats nematodes (multicellular insects).
How to Manage Soil Mites in my Home
I have written a dedicated article on managing unwanted (really?) soil mites. Just a heads-up that soil mites are a way to manage fungi gnat larvae in indoor pots. Do you want the helpers gone?
Also, they don’t invite their cousins to visit so that the parasitic mites will stay on the rats and birds outside. Of course, if you remove rats or nests in your ceiling, the remaining mites might seek alternative accommodation, but they won’t be in the soil.
FAQs on A Closer Look at Soil Mites
In Summary
Soil mites are your friends working with you and an army of soil organisms to ensure your plants have the best possible environment to grow and thrive. The only association between soil mites and the notorious red two-spotted spider mites is that they’re both mites, but the predaceous soil mite helps you manage this and other pests.
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