How to Get Rid of Spiders on Outdoor Plants
Being attacked by something you can't see is the stuff of nightmares, but we're not talking about ghosts. Spider mites, which aren't always visible to the naked eye, can launch swift assaults against your trees, shrubs, flowers, garden fruits and vegetables, and house plants
Since spider mites are practically invisible, it's not easy to get rid of them. But you can fight them with biological control methods, natural home remedies, or chemical pesticides.
Short on time? Try one of these top-rated spider-mite controls:
What are Spider Mites?
Cousins to ticks, spiders, harvestmen (aka daddy longlegs), and scorpions, spider mites are tiny arachnids, rather than insects. They're about the size of a single grain of sugar, so these oval-shaped, eight-legged critters are tough to spot without the aid of a microscope or magnifying glass
Spider mites come in several varieties. There's the Southern red spider mite, the carmine spider mite, the strawberry spider mite, the spruce spider mite.
Most common of all is the two-spotted spider mite. Yellowish-orange with one dark spot on both sides of its body, these mites live together in colonies. They cling onto the undersides of leaves and feed off the plant's chlorophyll.
Spider mites, while not harmful to humans but potentially lethal to plant life, live for about three to four weeks.
Despite their short life cycle, they reproduce rapidly. At just 5 days old, females start laying eggs, depositing a few hundred of them during her lifetime. These eggs only take about 72 hours to hatch.
Depending on the type, other spider mites range in color from red to green to purple to black to translucent.
Active during the warm, dry conditions of summer, spider mites can move from plant to plant, or outside to inside, by hitching rides on people and other plants.
Telltale signs of an infestation include white or yellow specks on leaves, webbing on plants, and dropping leaves.
Other pests can produce similar problems, so make sure you're dealing with spider mites before planning your eviction campaign.
How can you tell if you have a spider mites problem? The University of Minnesota Extension recommends holding a sheet of white paper or a paper plate under leaves where you suspect an infestation . Then, tap the leaves, and if mites are there, you'll see little specks fall onto the paper and scurry around.
Once you identify spider mites, it's time to get rid of them.
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How to Get Rid of Spider Mites Naturally
1. Biological controls
Natural predators, such as lacewings, thrips, ladybugs, and predatory mites ( Phytoseiulus persimilis) , keep spider mite populations in check . To encourage these beneficial insects to stick around, avoid using pesticides. Mulch flower and garden beds, and water regularly .
You can order live predatory mites and insects online for your indoor plants. Release them into the pots. These predatory mites and insects can consume hundreds of mites a day and don't pose any danger to plants, people, or pets.
2. Essential oils
A 2017 study found chamomile, coriander, spearmint, and rosemary essential oils are the most effective at killing two-spotted spider mite eggs and adults . To use this DIY method, fill a spray bottle with water and a few drops of your chosen oil from the recommended list, and apply it to affected leaves .
Neem oil sprays also work against spider mites by suffocating them.
3. Hot peppers
Extracts from peppers (bell peppers, jalapenos, chile, and cayenne peppers) were tested for toxicity against spider mites. These peppers killed about 45% of adult spider mites. Other pepper varieties, such as lemon drop peppers and Bishop's crown peppers, also repel spider mites.
You can buy hot pepper repellent online, in stores, or, you can make your own pepper repellent.
4. Other home remedies
Dish soap: The Oregon State University extension service recommends mixing 3 tablespoons of dish soap with a gallon of water to kill spider mites. Spray the soap solution on infested plant leaves weekly, as needed.
Rubbing alcohol: The rubbing alcohol you have around the house also can kill spider mites. Soak cotton balls in rubbing alcohol and wipe across the foliage of infested houseplants. Let either the dish soap or rubbing alcohol sit on the plants a few hours, and then rinse the leaves thoroughly with water.
Spraying water from a garden hose also will help wash away any spider mites that may have avoided the effects of homemade repellents. Washing away spider mites is a temporary solution, though, as these plant pests may return after each rinse.
How to Get Rid of Spider Mites Chemically
Spider mite problems may resolve on their own, especially if their numbers are low and your yard attracts their natural predators. But if other DIY methods haven't worked for you, control spider mites with pesticides.
1. Insecticidal soap or horticultural oil
While you generally should avoid using pesticides because they can kill beneficial insects, there's a version that will eliminate spider mites and nothing else. Only effective on contact with adult spider mites, insecticidal soap or horticultural oil should cover both sides of leaves.
Note: If your plants are stressed from drought or outside temperatures are high, do not use insecticidal soap or horticultural oil. Check the labels of these products to see which plants can safely withstand application. Some plants are too sensitive to the ingredients.
Insecticidal soap (or horticultural oil) will most likely work best for indoor plants, where the environment is climate-controlled.
2. Diatomaceous earth
Diatomaceous earth, which is made from fossils of aquatic organisms, is an organic pesticide that is lethal to arachnids and insects but non-toxic to humans. Sprinkle the food-grade version on infected plants and soil. It will dehydrate the spider mites' exoskeletons, killing them.
3. Other pesticides
Traditional pesticides, like the ones containing pyrethroids (components of the chrysanthemum flower), do not work on spider mites, according to the University of California's integrated pest management office. Instead, these types of insecticides can harm the natural predators of spider mites, allowing the mites to continue reproducing.
How to Keep Spider Mites Off Plants
Preventing spider mites from attacking your plants in the first place is the goal. Before introducing any new houseplants into your home, use the white paper test mentioned earlier to check for signs of the mites. If mites are present, do not purchase that plant.
Once home (with an uninfected plant), don't display your new greenery near open windows or heat vents. Spider mites could enter from outside, and they thrive in warm, dry places. Keeping dust on plants to a minimum also can help keep spider mites away. Simply wipe plant leaves with a damp cloth weekly.
Regular watering of your plants can repel spider mites, as these pests prefer dryness.
Spider Mites: Other Things You Need to Know
1. How long does it take to get rid of spider mites?
If your infestation isn't severe, depending on the spider mite control method, it will probably take a few weeks to completely get rid of the mites. If you opt for sprays, apply them weekly until the problem is under control. If you use predatory insects, your spider mite problem may disappear more quickly, as these insects can devour hundreds of mites a day.
2. What types of plants do spider mites like?
Spider mites feed on the cells of hundreds of varieties of plants. They like outdoor plants, such as melons, strawberries, tomatoes, and fruit trees. Inside plants spider mites favor include ornamental flowers and shrubs.
3. Should I throw away a plant with spider mites?
If these houseplant pests are out of control, you can bag up the entire plant and toss it out with the trash. It's a quick, permanent way to get rid of spider mites. Getting rid of the infested plant also prevents the mites from transferring to another one of your indoor plants.
When to Call a Pest Control Expert
Severe infestations may require help from pest control professional. These pros will come to your home, identify the pests, assess mite damage, and develop a plan to get rid of the spider mites.
Using integrated pest management, these specialists will not only exterminate your spider mite problem, but they also monitor the situation and help educate you on ways you can prevent a recurrence.
Now, instead of nightmares, your dreams of a pest-free plant collection can become a reality.
Main Photo: Mokkie / CC BY-SA 3.0
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Andréa Butler
Descendant of the Fulani tribe, Gettysburg-obsessed Marine Corps brat, and lover of all things writing and editing, Andréa Butler launched Sesi magazine and has penned articles for sites, such as LivingSocial, Talbot Digital, Xickle, Culturs magazine, and Rachel Ray. Andréa holds a B.A. in English from the University of North Carolina at Greensboro and an M.A. in magazine journalism from Kent State University.
How to Get Rid of Spiders on Outdoor Plants
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