Soil Mites

​Stop getting rid of soil mites!

There are certainly plenty of bad mites: dryberry mites, Eriophyid mites, plum bud gall mites, and two-spotted spider mites are just a few. But not all mites are bad. Like their predatory cousins, European red mites, soil mites are your helpers.

Electron scan micrography of thistle-eating rust mite. Photo by Eric Erbe; digital colorization by Chris Pooley, USDA, ARS, EMU) Public Domain

Soil mites are extremely beneficial when it comes to releasing nutrients into the soil and controlling pest populations.

Conduct an online search for ‘soil mites’ and you’ll see dozens [millions] of sites telling you how to get rid of these pencil-point size arachnids. But getting rid of them is the last thing you should do. So, what’s so great about soil mites? Let’s find out!

What are soil mites?

Mites are arthropods. This means they have an external skeleton, a segmented body, and jointed legs. They are also arachnids, like ticks and spiders, but very tiny. If you were to take a sample of soil that weighed about the same as a bar of soap, 100 g give or take, you might have 500 mites from 100 different genera in that sample. These buggers are really tiny. With the naked eye, they might look like nothing more than little brown or white dots. But these little guys are important.

While there are over 20,000 known soil mite species, with an estimated 80,000 total, it is easier to categorize soil mites by what they eat. They can be herbivores or carnivores.

Algae-eating soil mite ‘Nanorchestes’ (William L. Nicholson, Ph.D., CDC) Public Domain

Plant-eating soil mites

To something as small as a ballpoint pen tip, fungi make a great meal. So do bacteria and lichen. These scavengers are abundant in most soils and they help plants gain access to nutrients. As these soil mites graze on the fungi and bacteria that grow on root surfaces, they poop out those meals in the form of plant food. They also shred decaying plant material as they feed on the bacteria and fungi clinging to those plant surfaces. Fungal feeding mites (Oribatei) look like little orbs. Also known as turtle mites, moss mites, and beetle mites, these soil mites are very tiny. Let’s call them moss mites. Moss mites range in size from 0.2 to 1.4 mm long. This means you could fit 10-90 of them across a dime, end-to-end, depending on the species.

Insect-eating soil mites

Other soil mites are predators. Predatory soil mites feed on microscopic garden pests, such as nematodes, fungus gnat and thrips pupae, springtails, other mites, and the eggs and larvae of other insects. Most predatory soil mites are 0.5 mm long, brown, and found in the top 1/2” of the soil. [Unfortunately, I could not find any freely available photos of predatory soil mites.]

While not all mites are good, soil mites are your friends in the garden.

Let them be, and be glad they’re around!