Flat Mites

The term “flat mite” or “false spider mite” is a name given to a group of nearly 300 species of pest mites in the family Tenuipalpidae. They are related to spider mites, and their bodies are flat, hence the nickname. The most common species of Tenuipalpidae on our cultivated houseplants are the Brevipalpus mites.

Like spider mites, flat mites feed on surface leaf tissue, but unlike spider mites, the areas of their feeding tend to scar up, and they don’t make any webbing. Because they are microscopic, this damage tends to be the first indication you may be dealing with flat mites, as well as plant growth that is slowed or otherwise stalled.

Historically, flat mites were mainly an issue in tropical areas, where they fed on banana, rubber, and coffee plants, as well as palms. However, as the plant market has exploded over the past few years and imports have increased, we are increasingly seeing flat mites on houseplants—primarily Hoya, which have the thick waxy leaves that flat mites love.

The Flat Mite Life Cycle

What Flat Mites Look Like

Flat mites are microscopic, so you aren’t able to see them without a microscope. Flat mites have a signature orange/yellow color. Their bodies are somewhat translucent with an orange center. In addition to the orange color, they can also have some black or dark tints, depending on their sex, life stage, and species.

The eggs are tiny, bright orange dots. The eggs are sticky, which is why manual removal and rinsing down plants plays such a large part in getting rid of them.

Inspecting for Flat Mites

Because flat mites are microscopic, to confirm their presence, you’ll need a digital microscope or jeweler’s loupe that can magnify at least 50x.

If you don’t have a microscope, you’ll have to rely on the types of damage that are typical of flat mites, including scarring on leaves and stems, corking or hardening of petioles, and new growth dying off. You’ll often find the eggs clustered around the midrib of leaves and on the petiole.

Unlike pests like spider mites and thrips, flat mites don’t always spread throughout neighboring plants. In fact, it’s not uncommon for them to choose a single plant in a given area and only congregate on that one, despite neighboring plants being close by. Flat mites also seem to prefer specific types of plants, including Hoyas and Marantas, though they can be present on any type.

Examples of Flat Mite Damage

It’s easy for flat mite damage to go unnoticed. Your first sign will not always be visible damage, but rather that a plant whose growth has slowed or stalled—which can especially be difficult to notice in plants that are already known to be slow-growing. There may be a well-established population of flat mites on your plant before damage is noticeable.

Flat mites tend to feed on the undersides of leaves, so damage often presents as scabbing or browning on the leaf underside, especially around the base and petiole. You may also notice scabbing or corking around the petiole, which can make leaves more fragile and susceptible to falling off. Leaves may also appear deflated, as if the plant is underwatered.

On Hoya, signs of flat mites include the ends of vines or new leaves dying off. You may also notice the vines themselves looking dried out or hardened—this is normal for older growth as it matures, but not so much for newer vines.

Treating Flat Mites with Beneficial Insects