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Spider Mites

Spider Mites

Family Tetranychidae

Mitealso: Two-spotted spider mite, Red spider mite

Nearly microscopic sap-feeders, more closely related to spiders than insects, that erupt in hot, dry, dusty weather. The first sign is usually a fine pale stippling on the leaves; by the time you notice webbing, the colony is already large.

🔎 How to spot it

At less than 1/20 inch, spider mites sit at the edge of what the eye can see; a hand lens shows oval, eight-legged specks in shades of green, yellow, or red on the undersides of leaves. The clearest clues are the damage and the fine silken webbing they spin over leaves and shoot tips. Tap a suspect leaf over white paper and watch for tiny moving dots. Damage shows first as light stippling, then leaves that turn yellow, bronzed, or dry and drop.

🥀 Damage it causes

Spider mites pierce individual leaf cells and suck out the contents, leaving a fine pale stippling that spreads until leaves yellow, bronze, curl, and fall. Heavy infestations coat leaves, stems, and fruit in webbing and can defoliate or kill a stressed plant. Damage is fastest and worst in hot, dry, dusty conditions.

🛡️ Prevent it

Keep plants well-watered and unstressed, since drought-stressed plants suffer the most. Hose dust off the foliage and wet down dusty paths nearby, because dust encourages mites. Above all, avoid broad-spectrum insecticides such as carbaryl and pyrethroids, which wipe out the predatory mites and insects that normally hold spider mites down and often trigger a worse outbreak.

🧯 If it is already here

Knock populations back with a regular, forceful spray of water on the leaf undersides. For heavier infestations, apply insecticidal soap or a horticultural or neem oil, coating the undersides thoroughly and repeating, since these work only on contact. Conserve and lean on natural enemies; predatory mites are especially effective.

💡 Good to know

Spider mites reproduce explosively in warm weather, completing a generation in under a week, so populations can explode between waterings. Their natural enemies, including predatory mites, lady beetles, lacewings, and minute pirate bugs, usually keep them in check unless pesticides or dust knock the predators out. The two-spotted spider mite is the most common garden species.

🌱 Plants it attacks

714 plants in the library can be attacked by this pest

Acorn SquashAdirondack Blue PotatoAdzuki BeanAfrican Blue BasilAfrican MarigoldAgapanthusAgeratumAgrimonyAji Amarillo Pepper🍓Albion StrawberryAlice du Pont Mandevilla🥔All Blue PotatoAlmondAloe VeraAmbrosia CornAmerican BasswoodAmerican Beauty Dragon FruitAmerican BeechAmerican PersimmonAmethyst Falls WisteriaAmish Paste TomatoAnaheim PepperAnemoneAngelique TulipAngeloniaAniseAnise HyssopAnjou PearAnnabelle Smooth HydrangeaAnnual VincaApeldoorn TulipApple MintApril Tryst CamelliaArbequina OliveArizona Sun Blanket FlowerArkin CarambolaArmenian CucumberAroniaArp RosemaryArugulaAshwagandhaAsian PearAsian PersimmonAtemoyaAtlantic Giant Pumpkin🥕Atomic Red CarrotAucubaAugust Beauty GardeniaAunt Molly's Ground CherryAutumn Joy SedumAvocadoBachelor's ButtonBalsam FirBalsam PoplarBanana PepperBarbara Karst BougainvilleaBartlett PearBay LaurelBayberryBeach PlumBeauregard Sweet PotatoBecky Shasta DaisyBee Balm🍅Beefmaster TomatoBenarys Giant ZinniaBengal Tiger CannaBetter Boy Tomato🥬Bibb Lettuce🍅Big Beef TomatoBig Boy TomatoBilberryBing CherryBitter MelonBlack BeanBlack Beauty EggplantBlack Beauty ZucchiniBlack Beluga LentilBlack Cherry TomatoBlack CrowberryBlack Currant🍉Black Diamond WatermelonBlack Kabouli ChickpeaBlack Krim TomatoBlack RaspberryBlack Sapote🥬Black Seeded Simpson Lettuce🥕Black Spanish RadishBlack Tartarian CherryBlack WalnutBlack-Eyed PeaBlack-eyed Susan VineBlood OrangeBloomsdale SpinachBlue Bird DelphiniumBlue Bird Rose of SharonBlue FescueBlue Lake Green BeanBluecrop BlueberryBocking 14 ComfreyBok Choy

For educational and informational purposes only. Pest control advice is general guidance drawn from university cooperative extension sources; always identify a pest positively and read and follow the label on any product before use, especially around food crops, children, and pets.