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Spider mites are tiny, hard to spot, and they reproduce at an alarming rate. By the time you notice the stippled yellowing leaves and fine webbing on your plants, you’re already dealing with multiple generations. The good news is that sprays and oils kill them effectively. The bad news is that a single treatment almost never finishes the job – you have to commit to a schedule.
Repeat Treatments Every Week to 10 Days
Before anything else, get this into your head: one application won’t work. Spider mite eggs hatch continuously, and whatever spray you use today won’t touch the eggs that hatch tomorrow. To actually break the infestation cycle, you need to treat repeatedly.
Whatever method you choose below, mark your calendar for 7-10 days out and treat again. That timing catches newly hatched mites before they can lay eggs of their own. Keep going for at least three rounds (three to four weeks total). Stop early and the population bounces back stronger than before.
Insecticidal Soap
Insecticidal soap kills mites on contact by dissolving their protective outer coating. Fast, effective, and safe for plants when used correctly.
Mix 1 tablespoon of pure liquid castile soap with 1 quart (1 L) of water. Don’t use dish soap with degreasers or antibacterial agents – they can scorch plant tissue. Spray the solution directly onto infested areas, coating both the tops and undersides of leaves. The soap has to physically touch the mites to work, so thorough coverage matters.
Apply in cool, shady conditions to prevent leaf burn. Reapply every 5-7 days. Because soap doesn’t leave a residue, beneficial insects visiting after the spray dries won’t be harmed.
Neem Oil
Neem oil works differently from contact killers. It disrupts mite feeding, prevents eggs from hatching properly, and acts as a repellent – all at once. And once it dries, it leaves beneficial insects alone.
Mix 1-2 tablespoons of neem oil per 1 gallon (3.8 L) of water with a few drops of dish soap as an emulsifier. Spray every surface, especially leaf undersides where mites hide and breed. Apply in early morning or evening – hot sun and neem oil on leaves is a recipe for burn damage. The smell is strong but fades within a day.
Reapply every 7-10 days. Neem is particularly useful because it targets mites at every life stage, not just adults. Test on a small leaf section first if you’re unsure about plant sensitivity.
Horticultural Oil
A step up in strength from soap. Horticultural oil kills by clogging mites’ breathing pores – fast and thorough. You can buy it pre-mixed or make a rough equivalent with a few tablespoons of vegetable oil, dish soap, and water (though the commercial version has better emulsification and sticks to leaf surfaces more evenly).
Spray all leaf surfaces including undersides, which is where mite populations concentrate. The oil has to physically coat the mite to work. Don’t apply to heat-stressed plants or when temperatures are above 90°F (32°C) – the combination of heat and oil can burn leaves badly. Wait at least two weeks between applications because oil residue accumulates and can interfere with the plant’s ability to exchange gas through its leaf pores if you apply it repeatedly in a short window.
Isopropyl Alcohol Spray
This one surprises people. Seventy percent isopropyl alcohol (standard rubbing alcohol from the pharmacy) kills mites on contact by dissolving their exoskeletons. It works in seconds.
Fill a spray bottle with 70% isopropyl and spray directly onto visible mites and affected areas. After 4-5 minutes, rinse the plant with clean water. The rinse step is not optional – alcohol left on leaves too long causes damage. Safe for most plants, but test a small area first if you’re cautious.
This is a good option when you want immediate knockdown before starting a longer oil or soap rotation.
Spinosad Treatment
When soaps and oils haven’t been enough after a few rounds, spinosad is your next move. It’s derived from naturally occurring soil bacteria via fermentation, breaks down quickly in sunlight, and is considerably safer than synthetic pesticides. Available as sprays and concentrates at garden centers.
Coat all leaf surfaces thoroughly when spraying, paying attention to the undersides. Spinosad works best on young mites and has some residual activity lasting a few days after application, so 10-14 day intervals between treatments are usually enough to break the cycle. One important note: rotate spinosad with other methods rather than using it every single cycle. Like any pesticide, mites can develop resistance if exposed to it exclusively and continuously. Use it for two or three rounds, then return to soaps and oils before coming back to it.
Reserve spinosad for persistent infestations where the gentler methods have genuinely failed. It’s more potent than soap or neem and you want it to remain effective when you need it.
