Garden pests

Spider mites

Tetranychus urticae and related species · Mite

Also called red spider mite (UK), glasshouse red spider mite (UK), two-spotted mite (Australia), twospotted spider mite (USA).

Illustration

Tomatoes, beans, strawberries, fruit trees, roses and indoor plantsSap-sucking mite (not an insect)Spreads by wind, crawling and infested plants

Tiny eight-legged mites that feed under leaves, leaving fine pale speckling, bronzed leaves and silk webbing. They thrive in hot, dry, dusty weather; water plants well, hose the leaves and protect their predators.

How to spot it

Fine pale speckling on the upper side of leaves.
Leaves that turn dull, bronze or yellow, then drop.
Fine silk webbing over leaves and shoot tips in bad cases.
Tiny oval mites under 0.5 mm on leaf undersides: yellowish-green with two dark spots, or orange-red in autumn and winter.

Easily confused with

Thrips

Silvery patches dotted with tiny black specks of excrement, and no webbing.

Leafhoppers

Coarser pale spots, insects that jump when disturbed, and white cast skins stuck under the leaves.

Where it's a problem

Australia: Two-spotted mite is found throughout Queensland on fruit, vegetables and ornamentals. Numbers climb fast in hot, dry weather, and the predatory mites that keep it down are scarce in the tropical north.
United Kingdom: Mainly a greenhouse and houseplant pest from March to October, but it can also cause problems outdoors in hot, dry summers.
North America: In California it is worst from June to September in hot, dusty conditions, and often after sprays for other pests have killed its predators.

What to do

Tap a speckled leaf over white paper and look for tiny moving specks; a hand lens helps.
Water plants well, as mites build up fastest on dry, stressed plants.
Hose leaves, especially the undersides, with a strong spray of water, and damp down dust.
In a greenhouse, mist plants to keep the air humid, and consider predatory mites as a biological control.
Clear out badly infested plants at the end of summer so the mites don't overwinter.
Avoid broad-spectrum sprays for other pests; they kill the mites' predators and can set off outbreaks.

Spider mites aren't insects, and insecticides rarely work on them; the wrong spray can make an outbreak worse by killing their predators. If you use a miticide, choose one labelled for spider mites and follow the label and local rules, and remember that mites can become resistant.

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Sources

Facts checked Sunday 27 September 2026. General guidance only: follow your local council, agency and product label.