Red spider mite is a tiny mite of the Tetranychidae family. This sap-sucker infects indoor and outdoor plants.
Red spider mite facts
Name – spider mite, red spider
Family – Tetranychidae
Danger to plant – fatal if too many
Side effects – may cause viral diseases
Appears in – spring & fall (year-round indoors)
Spread – fast (crawls, wind-carried)
Treatment – moisture & biocontrol
A few red spider mites will only cause little damage. Too many, though, can kill a plant in a couple months.
Here’s how to eliminate red spider mites with organic treatments.
→ These treatments also work against scale insects
Red spider mite symptoms
Their tiny size (half a millimeter or 1/64″) makes spider mites very difficult to see with the naked eye, but a small magnifying glass lifts any doubt. Red spider mites feed on sap, sucking it out of leaf cells.
- First symptoms are appearance of small white or yellow dots and then leaves turn completely yellow (example on this spotted bean plant leaf).
- Unlike thrips that cause large white patches, red spider mite feeding is randomly spread around the area.
- For that, spray or mist water to check if small webs appear.
- Shown just above, a red spider mite that specifically attacks gorse: Tetranychus lintearius
Webs protect spider mites from predators and keeps humidity out.
Treat against spider mite
As mentioned earlier, red spider mites love it when the air is very dry. And the antidote to dryness is 💦 moisture 💦 !
→ Water treatments should be repeated daily, and other forms are best repeated every 2-3 weeks to get rid of new hatchlings.
→ Although red spider mites rarely cause severe damage, check on your plants often, especially in hot, dry weather. That is when they reproduce fastest.
Get rid of spider mite on houseplants
On houseplants, getting rid of them is straightforward:
- Spray rainwater every day on leaves to create a moist environment (another trick is to use leca beads under the pot). They’ll disappear within a week. A simple hand-spray does the job.
- Rainwater is best, demineralized water also works fine.
Hosing down & showering flushes red spider mite away.
- Move the plant to a sink or tub first. Wrap the pot in a plastic bag with a knot tied around the trunk to keep soil from washing out.
- For smaller colonies, wipe a soft moist cloth on leaves (top- and underside). Clean them daily until you don’t see any more red spiders.
- If that isn’t enough, organic mite-killer products below are an option, too.
Control spider mite in greenhouses or outside
Biological control is effective and doesn’t require daily work. You can find these online or in stores, but in the long run it’s best to make your garden attractive for all sorts of animals and insects.
- Red spider mite natural predators – Phytoseiulus and Galendromus are beneficial spider mites that eats pest mites, just like mite-eating ladybug, lacewing larvae and predatory thrips.
- Fungus against red spider mite – Beauveria bassiana is a type of fungus that greatly reduces red spider mite fertility and egg hatching.
- Bordeaux mixture is an organic pest killer.
- Spiders (real ones this time) also devour red mites.
- Herb decoctions, extracts and essential oils work well, too.
Essential oils/extracts kill both red spider mites and their eggs.
Trials show that many natural pesticides help get rid of the pest. Pyrethrum-based insecticides are a good example of this. Also, below, you’ll discover a list of spider-mite repelling plants and herbs.
What makes red spider mites appear?
Red spider mites multiply and attack plants when the weather is hot and dry.
That’s why they are found indoors all year round and in the garden in summer, when it doesn’t rain and temperatures stay above 70°F (20°C).
⚠️ These spiders aren’t insects! ⚠️
Using pesticides contributes to their spread:
- Insects are their predators. Killing mite eaters results in more mites.
- Red spider mites quickly adapt to chemical attacks. They build up immunity within a few generations.
How fast do red mites spread?
A spider mite’s lifespan is 4-7 weeks. They reproduce very quickly, like scale and aphids, so an invasion is devastating if not caught early. A healthy plant can be overrun in about 6 week’s time, if not treated.
- Moreover, they crawl and fly from one plant to the next, spreading fast.
Red spider mite repellents
Certain plants repel red spider mite near where they’re planted. Such protection usually extends about 3 feet (one meter) around the healthy, mature plant.
Herbs that fend off red spider mite:
- Marjoram and thyme stay small: great for planting together with taller houseplants.
- For rosemary, peppermint, chamomile and lemongrass, it’s the opposite. Give each a pot of its own and place it near vulnerable plants.
Vegetables that repel red spider mite:
- lettuce, chili pepper, wild tomato
Trees and shrubs that repel red spider mite:
- eucalyptus, neem, pongam, malabar nut
- vitex (not a repellent per se, but a decoy plant)
Flowers that repel red spider mite:
Mites similar to red spider mites
- Thanks Neil for the pointer in the comments!
These soft-looking velvet spiders don’t have any typical Tetranychus long hairs on their body, so don’t eliminate them. They’re great helpers to have in the garden to control pests!