We love spider mite predators! Here’s why. If you have fruit trees, vegetables, berries, vines, or ornamental plants, then you know the frustration mites cause you and your garden.
And if you’ve never had mites ruin your crop, I’ll describe it from personal observation. Imagine this gardening scenario.
Your plant is doing just fine, thriving and growing abundantly in the warm season’s brilliant sun.
Then, white dots and pale markings appear on the leaves, but the plant seems otherwise unaffected. The white spots start appearing in clusters and spreading, and the leaves become crooked; the growth slows down.
All of a sudden, you notice thin, spider-like webbing running between the leaves. And if you look closely, you start seeing tiny living dots moving along the threads and aggregating on the leaf’s undersides.
After some time, the white spots have become bronze or pale-silverish patches, and the plant is already in decline – showing stunted growth, deformed foliage, and the inability to grow healthy shoots.
If this is the case, you probably have too many spider mites, common pests in crops and home gardens.
But no worries! We’re about to brainstorm several mite predators that hungrily feast on mites.
Then let’s continue.
- What Are Spider Mites?
- How Do Spider Mites Damage Plants?
- What Do Spider Mites Eat?
- What Are the Best Spider Mite Predators?
- Types of Spider Mites
- How to Recognize Spider Mites
- How to Test for Spider Mites
- What Kills Spider Mites?
- What Are the Predators of Mites?
- Predatory Mite Species for Gardens
- Garden Bug Mite Predators
- How to Establish Spider Mite Predators?
- Final Words
What Are Spider Mites?
Spider mites got their name because they can thread webbing like spiders (unlike many other mites that move around freely). Like all other mites, they’re not insects but arachnids – like spiders and ticks.
In the worst spider mite outbreaks, the entire plant gets covered with webbing – it’s a “mite city,” essentially. Also, the foliage turns rusty and dry.
How Do Spider Mites Damage Plants?
Spider mites suck plant juices and create numerous colonies that spread rapidly. Since they’re so inconspicuous, they easily integrate into the garden from new plant material and are blown in by the wind.
The web-spinning mites are especially attracted to plants suffering from drought stress.
When an infestation occurs, many mites per plant affect plant growth, but the size makes them difficult to spot until the damage sets in.
In worst cases, they can even kill an ornamental plant, especially an annual or biannual. With trees and shrubs, mites can affect flowering, fruiting, and fruit quality.
What Do Spider Mites Eat?
All species of spider mites affect plants similarly. They all feed on a wide range of plants, poking almost microscopic holes and sucking on their juices.
Don’t be fooled by the webbing – unlike spiders, they use it only to move around easier, not for hunting any prey. Unfortunately for gardeners, the plants are their only targets.
The preference for specific plant types depends on the spider mite species, but on farms, they are notorious for infesting fruit trees and shrubs, possibly affecting tree health and yields.
What matters regarding spider mite management is not what they feed on but when they feed – there are warm-season and cool-season species.
What Are the Best Spider Mite Predators?
Ladybugs, spider mite destroyers, sixspotted thrips, spiders, and various predatory mites are arguably the best spider mite predators. Some of the most prominent predatory mite species include Typhlodromus pyri, Typhlodromus occidentalis, Phytoseiulus persimilis, and Amblyseius andersoni.
But these aren’t the only predatory mites that devour and ambush spider mites. There are many others! We’ll review more in a moment – and share many neglected predator mite nuances that gardeners overlook.
Types of Spider Mites
There are several species of spider mites, but the most common garden pest is the Two-Spotted Spider Mite or Strawberry Spider Mite (Tetranychus urticae). Under magnification, they’re easy to identify due to their saddle bags-like two spots on the sides of their back.
Other impactful spider mite species include:
- European red mites (Panonychus ulmi)
- Pacific spider mites (Tetranychus pacificus)
- Spruce spider mites (Oligonychus ununguis)
- Southern red mites (Oligonychus ilicis)
Two-Spotted Spider Mite
The infamous two-spotted spider mite is the most prevalent species. And it’s a typical warm-season mite. It affects over 180 plants, from weeds to crops to houseplants.
After overwintering in the soil or on the host plant, the female spider mites become active in April and May, seeking suitable spots on leaf undersides to lay 100 or more eggs.
The hatching period can vary between 20 days in chilly springs and only five days in warm weather. That is why the populations boom when it’s hot outside. They’re also active in cool weather but rarely grow to damaging proportions.
This mite strikes hardest when conditions are hot and dry and when plants suffer drought stress. Keep your plants hydrated and give them regular water sprays, and you’ve already done a lot to prevent two-spotted spider mite damage.
Spruce Spider Mite
If you thought your garden is spared of mite attacks because you live in a cold and humid zone, you’re wrong – and be especially worried if you’re a Christmas tree grower.
The spruce spider mite is a specialized cool-season mite. As the name suggests, it targets conifer trees such as spruces, firs, pines, and junipers.
The spruce spider mite is active in two seasons. The eggs hatch from March to April, and the mites are active until the temperatures exceed 86°F for three consecutive days. The nymphs and adults then become dormant until the fall, when they continue to feed.
Interestingly, autumn and spring plant damage by the spruce spider mite, such as yellowing and bronzing of the needles, usually doesn’t show until the summer heat arrives. That is why you should be on the lookout for tell-tale webbing with mites.
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How to Recognize Spider Mites
Spider mites are hard to see. But if you notice white dots, pale, silverish, or bronze patches, or webbing on the leaves, then check for spider mites underneath.
The webbing is usually present around the entire plant, unlike regular spider webs that are generally in one area (but baby spiders can sometimes “simulate” spider mite webs).
How to Test for Spider Mites
Put a piece of white paper underneath a leaf (or the section of a plant) and make a few strikes. (Tap it a few times.)
The mites that have fallen off will be visible as tiny whitish or pale-brownish dots crawling slowly on the paper’s surface.
Ten or more mites per plant or leaf sample (depending on the size) indicates that you should consider control measures. David Biddinger, a tree fruit entomologist and specialist in biocontrol agents at Penn State, says the following. (Paraphrased below.)
“When the number of mites per leaf reaches 25 to 30, the tree becomes stressed, and the leaves start to bronze; this affects the quality of its fruit and in two to three seasons can (actually) kill small trees.”David Biddinger, Fruit Tree Entomologist
However, the overwintering female spider mites become reddish-orange and are hard to differentiate from other, potentially useful, garden mites. Still, when crushed, the pest mites leave a green stain on the paper.
But what next?
The good news is that many predators naturally keep spider mite populations in check – and that’s what we’ll focus on.
What Kills Spider Mites?
Spider mites are present in most (if not all) gardening and farming environments, so having some is unavoidable. There is no sense in wanting to destroy all of them. However, various methods exist to control their numbers to avoid plant damage.
The first measure is to give affected plants a bath or a good water spray for a few consecutive days. Spider mites are discouraged by water. While they may not all die, they’ll get dispersed and their webbing destroyed when sprayed.
As for other means and products, I’ll start answering this question by saying what you shouldn’t use to kill mites – and many people will resort to it out of habit.
If possible, do not use pesticides to kill spider mites. They’re not very effective, and spider mites quickly develop resistance. Two, insecticides can make the spider mite outbreaks worse because you destroy all the beneficial mite predators that feed on them and keep their numbers in check!
Destructive spider mite proliferation often occurs after regular treatments with persistent insecticides like pyrethroids or carbaryl in crop production. In other words – these insecticides HELP spider mites.
There are specialized products that target mites specifically – miticides. But again, you kill off all the predatory mites that would love to show some predation skills on the pesky spider mites only if given a chance.
What predatory mites, I hear you ask.
If you have never heard of them before, you may be surprised.
Here's a natural method to help keep unwanted garden mites in check. Ladybugs! Ladybugs are the arch nemesis of various garden pests - and they hunt leaf hoppers, whiteflies, thrips, spider mites, moth eggs, and more. This bag contains 150 live and healthy ladybugs - ready to hunt and clear your garden of invasive insect and mite pests.
What Are the Predators of Mites?
Before you reach out for the first chemical product that cross-marketing advertisers must have offered you by now, let me tell you a few things about natural spider mite control.
In addition to water and humidity, fortunately, we have many natural allies to help us control spider mites in garden settings. These are the spider mite biological control agents.
While larger animals (e.g., songbirds) do not engage in mite predation, we’re lucky to have many hungry invertebrates that consider them a meal. After some time, the invaluable mite predatory effect becomes blatant. (IE – you will notice far fewer mites.)
Here is a list of creatures that can’t wait to munch on the spider mites. And no web will save them!
The notion of fighting fire with fire certainly applies to mites.
Thus, you can fight spider mites with other kinds of mites!
Predatory mites do not feed on plants or create webs. Instead, they roam around on plants, waiting to bump into a spider mite – and then suck it dry.
These arachnid predators are so effective in controlling spider mites that they’re one of the primary means of biological control of these plant pests.
If you have spider mites and a healthy garden, you already have predatory mites around feeding. However, you can also buy predatory mites – different species depending on your climate and the spider mite species you’re looking to target.
In agricultural crop production, predatory spider mites function as fierce and highly trained paratroopers that rain down on the fields from drones to bring havoc to the spider mite population.
Don’t believe me? Take a deeper look:
Predatory Mites vs. Spider Mites
If you’ve been wondering, “What is the difference between predatory mites and spider mites,” here is a quick checklist:
- Predatory mites don’t feed on living plant parts, although some feed on pollen.
- Predatory mites don’t form a web; spider mites do.
- Predatory mites usually occur as solitary and tend to wander from plant to plant (albeit slowly). But spider mites form pretty stationary colonies (except they move across their webbing and use air currents to spread around).
- When you squash and smear a predaceous mite on a white surface, the stain is yellow-to-reddish due to feeding on (you’ve guessed it) other mites.
- Phytophagous mites stain green from feeding on plant juices.
|Predatory Mites||Spider Mites|
|Feeds on living plant parts||No||Yes|
|Staining when squashed||Yellow, Orange, or Red||Greenish|
Predatory Mite Species for Gardens
Here is the ultimate list of predatory mite species for control of spider mites.
Typhlodromus pyri (aka Galendromus pyri) is a predatory mite found globally. It is present in various habitats, including orchards, but prefers (and is most efficient in) chillier and more humid climates.
T. pyri prefers to feed on the European red mite but will also move on the two-spotted spider mite and the Apple rust mite with a hefty appetite. Additionally, it feeds on pollen.
In North America, this is the most prevalent predaceous mite and best used in the orchards and gardens of the northeast and northern midwest US. It is among the most significant mite predators on blackberries, fruit trees, rose family plants, and sometimes hops.
A problem with T. pyri is that it’s slow-moving and doesn’t like to cover distances in search of prey, and will move into your garden slowly – sometimes too slowly.
To establish on your estate for free, clip and bring in shoots or clippings from nearby trees where you identified T. pyri. A fast-acting commercial approach is to buy and release it – but you will have to repeat the process occasionally.
Another limitation is that the species can thrive only with sufficient humidity. However, if you have an orchard with constant irrigation, such as drip irrigation, you may still enjoy T. pyri’s benefits, even in drier regions.
Western Predatory Mite – Typhlodromus occidentalis
Western predatory mite (Typhlodromusoccidentalis, aka Galendromus occidentalis) is T. pyri’s warmth-loving cousin and one of the most promising biocontrol options for apple orchards, as well as plum, peach, and cherry orchards in favorable warm regions.
Thriving in hot and warm conditions, it feeds only on other mites and prefers the two-spotted mite over the European red. In cooler climates, it becomes a dominant mite predator during midseason.
Also, T. occidentalis is more mobile than T.pyri. In all other respects, the two are similar and work well together as they cover different seasons and prefer slightly different prey.
Our next mite-y predator (pun intended) comes from a different family – Phytoseiidae. The Phytoseiulus species are bright red to orange creatures that can look like spider mites but lack tell-tale dark spots.
Phytoseiulus persimilis is a very efficient predator of many plant-feeding mites, consuming 5-20 mite adults or spider mite eggs daily.
Besides the predation rate, another advantage of Phytoseiulus persimilis is that it doesn’t have a resting stage and is active year-round if the temperatures are mild and can produce multiple generations. Thus, it can help in greenhouses and other indoor plantscapes.
These mites also belong to the Phytoseiidae family.
What’s cool about them is that, besides mites, they feed on other damaging insects like thrips and whiteflies.
The broad taste of Euseius mites is that they can sustain themselves even after the mite outbreak has subsided – which may be a problem with species that eat mites only, like Typhlodromus occidentalis.
This species is arguably the second most vital predatory mite in organic or integrated pest management for Europe, right after T. pyri.
Found all over the Northern Hemisphere, it feeds on European red mites, Twospotted spider mites, Pacific mites, Apple rust mites, Prown mites, Cyclamen mites, thrips, and pollen.
Its favorite plants to scout include maple, apple, and pear, making A. andersoni a valuable ally in apple orchards and pear orchards.
Other Predaceous Mites
Other predatory mites include Mesoseiulus longipes, Metaseiulus citri, Neoseiulus californicus, Neoseiulus fallacis, and Galendromus flumenis.
We also believe many more predatory mites exist that are still undiscovered. We bet scientists will likely discover and facilitate other species in the future.
Garden Bug Mite Predators
Mites aren’t the only creatures that hunt leaf-sucking spider mites. Much larger insects (and arachnids) also mercilessly prey upon them. Here are some of our favorite examples.
Ladybugs is a group name for beetles from the family Coccilnelindae. They’re best known as aphid predators. But they also snack on web-spinning mites.
Among about 5,000 species of ladybugs, the most prolific mite hunter is the spider mite destroyer ladybug, Stethorus punctum. What a name, huh?
Somewhat logically, spider mite destroyer dwells within orchards, strawberry fields, the adjective forest habitats, and on crops struck by spider mites. Adult beetles remain active until September or late October.
Sixspotted Thrips (Scolothrips spp.)
I know that thrips get a bad rap as destructive garden pests. Species like the western flower thrips probably do annual agricultural damage measuring millions of dollars.
But hold your horses (and thrips!).
While most species we know are phytophagous and suck plant juices, there are also predatory species – and they feed on spider mites.
Such is the case with the sixspotted thrips from the genus Scolothrips. They occur anywhere where the web-spinning mites are abundant and feed on all stages of spider mites, although they seem to prefer the immature forms.
The Sixspotted thrips show many talents as mite predators. They eat adult spider mites, nymphs, and eggs. And they can consume many. Yet they also sustain themselves and reproduce with scarce prey. Plus, unlike predatory mites, they possess excellent searching skills – even when mite densities are low, these thrips remain efficient hunters.
Lacewings are gentle, elegant, fly-like insects that feed on pollen and nectar as adults but are fierce predators in their larval stage.
Baby lacewings also eat spider mites. Some estimates say that if it was hypothetically to feed on spider mites only – a single lacewing larva could take out as many as 11,000 mites!
However, lacewing larvae eat other pests, such as aphids, whiteflies, mealybugs, caterpillars, and moth eggs, so their cravings get more evenly distributed.
Hoverflies (Syrphidae) are so underappreciated as garden allies.
While all the attention on pollinators goes to bees, the Syrphids are among the most important pollinators. But it doesn’t end there.
Like lacewings, hoverfly larvae don’t fall for the flower power but are voracious generalist predators in the gardens – and mites are also on their menu.
Researchers tell us that a single baby hoverfly can destroy 100-400 aphids before it pupates – depending on the size of the hoverfly species and the size of a caterpillar. There is no data on mites; however, as mites are tinier than aphids, it is safe to estimate that hoverfly larvae can eat many more mites.
Besides aphids and mites, other Syrphid larvae prey includes aphids, ants, caterpillars, froghoppers, and scales.
Minute Pirate Bugs (Orius spp.)
Like thrips, true bugs (Hemiptera) are better known as garden pests than benefactors. However, this diverse insect group also has many efficient predators that scout our gardens for prey.
Due to their small size, minute pirate bugs target tiny garden arthropods and their eggs. Check out their impressive prey list. It includes several annoying garden pests such as aphids, thrips, aphids, whiteflies, moths, and – mites.
Minute pirate bugs are available to buy as biological control but also occur naturally in the garden and agricultural landscapes.
To encourage their presence, leave some natural vegetation at the edges of your fields and abstain from using insecticides. Like many insects, these beneficial insects are hard-hit by excessive pesticide use.
Jumping Spiders (Salticidae)
These adorable spiders are generalist garden predators, happily hopping around the garden and hunting down prey smaller than themselves.
Unlike other web-spinning spiders, jumping spiders are active hunters. While a mite will not get entangled in a regular spider web, it can easily get tracked down and eaten by an active spider hunter that doesn’t use webbing.
Although they have no strong habitat preference, from my observation, they seem to favor warm, sunny spots, so the warmth-loving spider mites are most likely to end up on their hit list.
Unfortunately, beneficial spiders get killed by miticides and acaricides used to control mites, and orchard insecticides can give them a brain disorder. Thus, if you care to have these puppy-8-eyed spiders around to help you, then abstain from using chemicals.
How to Establish Spider Mite Predators?
If you want the precious aid of mite predators, you have to know something.
All the beneficial spider mite natural predators have one thing in common – pesticides adversely affect them.
While some develop resistance, so do the targeted spider mites! Thus, fighting mites with pesticides becomes an endless chemical warfare damaging ecological and human health.
So, if you want an allied army in your spider mite battle, give up pesticide use, or at least apply them locally and as minimally as possible.
Also, save some natural micro-habitats on your property and edge your gardens and fields with native plants.
Spider mites are common in any garden landscape – there is no sense in striving to eliminate them.
However, you can ensure they don’t cause much damage by keeping their populations in check. The number of mites per plant or per leaf is vital to monitor.
Besides keeping your plants healthy, hydrated, and water-sprayed, and perhaps applying organic remedies such as oil spraying, the best way to control the pesky mite populations is by using predators of spider mites to handle them naturally.
Predatory mites, ladybugs, lacewing larvae, predatory thrips, pirate bugs, jumping spiders – all these creatures gladly munch on spider mites. Biological control is a win-win-win strategy – it benefits the animal biodiversity, the plants, and your wallet by excluding expensive chemical pest management costs.