Does Neem Oil Kill Spider Mites? (A Natural Solution)

Spider mites are a common problem for plant lovers, whether it be indoors or outdoors. These tiny pests can get out of control if you’re not vigilant, as they reproduce at an astonishing rate. One female spider mite, only days old, can lay up to 20 eggs per day, and continue to do so every day of her three-week life cycle.

Spider mites feed on plants by sucking the chlorophyll from the plant’s cellular tissues, leaving behind dry, withered leaves and drooping stalks. If left unchecked, your plant may never recover.

Do your plants suffer from spider mites? Examine the stems and leaves of your plants carefully, paying close attention to the undersides of the leaves. Spider mites are tiny, only about 1/20 of an inch in size, and may be difficult to see.

Check for the following spider mite symptoms:

  1. A smattering of pale speckles across the top surface of the leaves, referred to as “stippling”. This is often the result of missing chlorophyll that spider mites have consumed.
  2. Tiny black, red, or brown dots, clustered together, on any area of the plant, but most often on the undersides of leaves. This can point to the presence of spider mites or their eggs.
  3. Leaf curl – Often when spider mites attack a plant, the leaves will begin to curl at the edges, as a form of self-defense.
  4. Thin, wispy webs clinging to the stalks, leaves, and leaf stems, often with black, brown, or red dots visible.
  5. Larger patches of dry, white areas on the leaves, just before they ultimately die and drop off. This happens when the leaves have been robbed of chlorophyll by the spider mites feeding.

Don’t reach for chemical pesticides to kill this pest!

It’s been found that spider mite populations can increase with the use of common spray-on pesticides, such as Sevin and Orthene, due to the active ingredients, carbaryl and acephate. These compounds can increase the nitrogen in plants, favoring the development of spider mites.

Carbaryl and acephate can also create a phenomenon known as hormoligosis – the speeding up of the spider mite’s reproductive cycle.

Even botanical insecticides containing pyrethrin can flare spider mite infestations, as pyrethrin eradicates some of the natural predators of the spider mite.

Neem oil, however, is a safe and effective organic way to combat spider mites. In this article, we’ll discuss how it works, how to prepare and use neem oil to treat spider mites, as well as alternative methods for controlling and preventing spider mite infestations.

Does Neem Oil Kill Spider Mites?

Neem oil works to eradicate spider mites by using a diluted solution sprayed upon the leaves, leaf stems, and stalks of your plants. When the solution comes into contact with soft-bodied, small pests such as mites, the oil coats their bodies so thoroughly that it blocks the pest’s airways, effectively suffocating them.

Does Neem Oil Kill Spider Mite Eggs?

Although neem oil targets the adult and larvae stage of spider mites, there is some debate as to whether it will destroy the eggs on contact. However, if you’re applying neem oil correctly, and spraying all of the infested plant’s surfaces with repeat applications, you will be killing the larvae when they first emerge from the eggs.

Also, noteworthy – neem oil is effective in a two-fold manner. Besides suffocating the tiniest of insect pests, it also works by disrupting an insect’s life cycle once the active ingredient, azadirachtin, is consumed, which inhibits them from feeding and reproducing.

Does Neem Oil Prevent Spider Mites?

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Neem oil can be used as a preventative application and for an ongoing infestation.

The oil is made from pressing the seeds of the neem tree, which is indigenous to Southeast Asia. It has a strong odor, which some people refer to as sulfuric or garlicky. Fortunately, many garden pests don’t care for the flavor!

When used as a soil drench in a prepared solution, neem oil is absorbed into the plant’s system, and the leaves subsequently take on a flavor and aroma many bugs find unappealing. This can potentially lessen the amount of bugs, including spider mites, who choose to take up residence on your plant.

As neem oil spray applications can be washed away after a good rainfall, a soil drench is a handy tool for curbing and preventing spider mite infestations.

How to Mix Neem Oil for Spider Mites?

Whether it be for a soil drench or a sprayed neem oil application, the solution is prepared the same way. Using 100 % pure, cold-pressed neem oil is crucial, as any concentration less than pure will not be as effective, and, likewise, heat processing will denature azadirachtin, rendering it less powerful.

For every quart of lukewarm or room temperature water, add 1 teaspoon of neem oil, plus one drop of liquid dish detergent. The soap will act as an emulsifier, enabling the water and oil to properly mix.

Shake the solution well, and transfer to a sprayer. A plant mister will work fine for your indoor plants, but if you’re spraying a large number of outdoor plants, consider using a garden sprayer, which can hold one to several gallons. Only prepare as much neem oil solution as you plan to use in one application, as the mixture doesn’t hold up well for storage.

How to Apply Neem Oil to Kill Spider Mites?

For outdoor plants, you should only spray neem oil when pollinators are not present, such as extremely early in the morning, or better yet, in early evening, about an hour before dark. If you’re spraying indoor plants, it can be done any time of day, but consider moving the plants to a porch or setting them on a towel prior to application, as the mist may make floor surfaces slippery. Also, be considerate of household pets, as neem oil can be a mild irritant to the eyes.

Spray the leaves, stems, and stalk of the plants thoroughly until the solution drips a bit from the leaves. Be sure to reach the leaves’ undersides and every crevice, as the pests will try to hide from the spray. If you already have leaf curl on your plant, indicating a spider mite infestation, be aware the mites will hide in the curled-over part of the leaf. In all likelihood, it will take several applications before they’re completely eradicated.

A less messy way to apply neem oil is with a soft rag dipped in the solution for broad-leaved houseplants. Wipe the plant’s leaves thoroughly, paying particular attention to the underside. Try to wipe down the stalk and stems, as well.

As a soil drench, pour 1 – 2 cups of the solution into the soil around the base of the plant, depending on the pot size.

It’s best not to use neem oil on any plants that are stressed from over, under-watering, or recently transplanted. Also, be aware that thin, wispy foliage may be damaged by neem oil applications.

Refer to this related post for a list of plants not to use neem oil on.

How Often to Spray Neem Oil for Spider Mites?

Since neem oil only kills the spider mites it comes into contact with, and the spray usually dries in about 45 minutes, it’s most effective when applied as a series of treatments.

Spray neem oil once every 4 days for an ongoing infestation or once every 7 – 10 days for preventative measures.

A soil drench can be applied every 2 – 3 weeks. Soil drenches and foliar sprays can be applied simultaneously but watch for signs of damage to your plant. If you notice foliage “burn”, increase the time between applications.

How Long Does Neem Oil Take to Kill Spider Mites?

Once applied to the leaves as a spray, neem oil will smother some spider mites instantly, by blocking their airways with oil. Unfortunately, there will always be some that get away, which is why repeat applications are called for.

If the mites feed on the leaves while neem oil is present within the leaf’s cellular structure (via soil drench), or on the surface (via foliar spray), the azadirachtin in the neem oil will usually take 3 – 7 days to kill them. The problem, then, is the eggs that have already been laid.

With repeat applications over a few weeks, you will eventually see success.

What Happens to Your Plants if You Don’t Kill Spider Mites?

Spider mites feed on the chlorophyll inside the leaves, sucking it up like sap. Plants need chlorophyll for the process of photosynthesis, converting food into energy. Without chlorophyll present, plants are unable to process nutrients found in the soil. If you allow a spider mite infestation to go unchecked, the plant will eventually wither away and die.

Are There Any Alternative Ways to Get Rid of Spider Mites in the Garden?

If you’d prefer not to use neem oil, consider these other methods of ridding your plants of spider mites.

  • Water – Spider mites multiply quickly in hot, dry conditions, and thrive in the dust that may settle on a plant’s leaves in arid climates. Consider misting your garden plants daily when the weather is dry for long periods. Also, spraying water jets straight at spider mites’ webs will help to dislodge them.
  • Soap – Try spraying insecticidal soap, or plain, soapy water on your plants, using the full coverage method described above. Repeat every 3 – 5 days.
  • Import natural predators – many natural predators would love to lunch on your spider mites. Order online from sites such as this one.
  • Companion plant repellents – The fragrance of some plants puts off spider mites. While planting companion plants as repellents won’t eradicate a spider mite infestation, it may lessen the chances of developing one. Try planting Chinese parsley, dill, garlic, leeks, lemongrass, peppermint, or rosemary to repel spider mites.

Decoy plants – If you tend to have a spider mite problem every year, try planting marigolds, and (regular) parsley a short distance away from your garden. Spider mites are attracted to these plants. Check periodically for infestations on your decoy plants and treat them appropriately.

Take heart – if the spider mites are stopping for the marigolds or parsley, they probably haven’t made it to your garden yet. Some gardeners prefer to plant marigolds and parsley among their vegetables as a decoy crop, but my personal preference is to keep these plants a short distance away from my garden.