Predatory Mites

Mites and spider mites are garden pests. They suck the life from your plants and spread disease. Unless they are predatory mites. Predatory mites are our allies, though you may never see them without a hand lens.

Predatory mite (Mick Talbot) CC BY 2.0

Predatory mite description

Generally speaking, predatory mites are pear-shaped and translucent. They may also be white or the color of their prey, usually reddish or brown. Nymphs look like tiny adults with the same coloration. Wedge-shaped eggs are clear or white.

Some predatory mites are smaller than others. The Western predatory mite (Galendromus occidentalis) weighs in at only 1/70th of an inch in length (0.36mm). This means you could line up almost 50 of them, end-to-end, across an American dime. But don’t let their size fool you.

Predatory mite species

Predatory mites may be incredibly small, but they can take a serious bite out of your mite (Eriophyidae) and spider mite (Tetranychidae) problems.​ There are hundreds, perhaps thousands, of different types of predatory mites. They are grouped into one of four categories:

• Type I feed exclusively on spider mites and will cannibalize when food is scarce. [Phytoseiulus persimilis]
• Type II feed on mites, spider mites, and thrips. [Neoseiulus fallacis, N. californicus, Galendromus occidentalis]
• Type III eat mites, spider mites, thrips, and whiteflies, as well as pollen, nectar, honeydew, and other predatory mites. [Amblyseius andersoni]
• Type IV prefer pollen but will occasionally eat mites and spider mites.

Different species have different favorite meals, so you can customize your protection with just a little research.

Predatory mite with prey (Dr. Monica Farfan) Public Domain

Predatory mite lifecycle

The life of a predatory mite is short. Once the eggs hatch, they quickly go through a 6-legged larval stage and two 8-legged nymph stages before reaching adulthood. In her 30-day life, an adult female predatory mite will lay up to 21 eggs on the underside of leaves, in flowers, and within the crevices of buds. Depending on the weather, those eggs will hatch in 1 to 4 days. There can be up to 10 generations each year.

It is difficult to know if predatory mites are present because of their size, but you can buy them. They will help protect your avocado, citrus, grape, plum, strawberry, and many other crops. Before you release your predatory mites, be sure to reduce dust in the area by giving everything a quick rinse with the hose. You’ll want to avoid broad-spectrum pesticides and miticides, as well.