Spider mites are tiny insects that are difficult to see with the naked eye, but can be very damaging to plants in a garden or park. If you suspect spider mites, check that before trying to get rid of them. Once you know that the pest is present on the plant, spray the insects with a water hose or use a horticultural oil to kill and prevent further infestation of the mites.
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Method 1 of 4: Watching for Signs of Spider Mites
Step 1. Look for yellow or brown spots on the leaves
Spider mites will weaken the plant and often have small yellow or brown spots on the leaves. You're also likely to see dry, fallen leaves.
Step 2. Check for webs on the plants
Spider mites will leave webs under the leaves and stems of plants. Check the plants daily to see if there are webs there.
Step 3. Look for mites with a magnifying glass
Since spider mites are less than 1 mm in size, these insects are difficult to see with the naked eye. Purchase a magnifying glass from a convenience store or the internet and examine the plants. If you see any tiny creatures moving on the leaves, they are most likely spider mites.
Step 4. Pat the leaves on a sheet of white paper
If you don't have a magnifying glass, use white paper to look at the mites. Hold a piece of paper under the leaf, then pat the leaf. If you see green, brown, or black dots moving across the surface of the paper, it means they are spider mites.
You can also crush these pests with your fingers. If it's green, it's a plant-eating mite. If it's orange or yellow, it may be a beneficial predator
Method 2 of 4: Getting Rid of Spider Mites with Water
Step 1. Isolate the infected plants
If you see spider mites and want to minimize the damage they do to your plants, it's best to separate the infected plants. Move to an isolated part of the garden or indoors before the mites are eradicated.
Step 2. Spray the plant with a hose
The water pressure from the hose spray is strong enough to kill spider mites. Point the hose at the plant and spray the leaves with cold water. Don't forget to spray the underside of the leaves to kill all the mites.
Step 3. Repeat this process once a week
Keep mite-affected plants separate for at least a month so they don't spread to other plants. The water from the hose is not strong enough to destroy spider mite eggs. So, spray the plants once a week for a month to make sure all the newly hatched mites die as well.
Method 3 of 4: Using Horticultural Oil
Step 1. Dilute the horticultural oil with warm water in a spray bottle
Horticultural oil is an oil-based product that can kill insects and their eggs. You can buy it at a plant store or online. Before diluting any horticultural oil, read the directions for use on the label so you know how much water to use and whether the oil is safe to spray on your plants.
- Use traditional horticultural oils in the summer.
- Use dormant horticultural oils in fall and spring.
Step 2. Move the mites into the garage or shed
Horticultural oils will be eroded by rain or high humidity and you can prevent this by incorporating them in. Do not use horticultural oil on maple, hickory, cryptomeria (Japanese cedar), and cypress trees. Read the instructions for use to make sure the product is safe for a particular plant.
Step 3. Spray the plants thoroughly with horticultural oil
Since water and oil separate, you must shake the bottle regularly when using it. Wet the top and bottom of the leaf with oil. Let the oil absorb and kill the mites and their eggs.
- Horticultural oils work by "suffocating" the mites. So, the whole plant must be completely wet.
- Do not spray the flowers with oil as this can damage them.
Step 4. Spray every 2-3 weeks until all spider mites are dead
Check for mites periodically throughout the rest of the week. If you see any mites still hatching, spray again.
Method 4 of 4: Preventing Spider Mite Attacks
Step 1. Prune the infected plant parts
If you notice webs on the branches or spots on the leaves, prune the area with pruning shears or cuttings. Throw the infected plant parts in the trash.
Removing mite-infested plants around the garden will allow the pests to spread to other plants
Step 2. Spray the plant with cold water
Humidity will prevent spider mites from invading plants. Moving the plant indoors and spraying it with water 2-3 times a day will reduce the chances of spider mite infestation. You can also place the plant in a tray filled with water to prevent it from attracting spider mites.
Step 3. Place a humidifier near the plant
Spider mites breed in dry conditions and a humidifier will help keep them away. Do not start the engine while you are applying horticultural oil.
