Spider Mite

Two-spotted spider mite is not an insect but an arachnid, closely related to spiders and ticks. Adults are oval, roughly 0.5 mm long and only just visible to the naked eye as tiny moving specks. They are pale yellow-green to greenish-brown with two dark spots on either side of the body, though colour can darken to orange-red in overwintering or stressed populations. Eggs are spherical, translucent to pale yellow, and laid singly on the underside of leaves. Nymphs resemble small, pale versions of the adults and pass through several moults before maturing, with the whole life cycle from egg to adult taking as little as one to two weeks in warm conditions.

All feeding stages are found on the underside of leaves, where they pierce plant cells with needle-like mouthparts and remove cell contents. Fine silk webbing is often produced across leaf undersides and between leaves and stems, particularly under heavy infestation, giving the pest its common name.

This is one of the most widespread and polyphagous mite pests in Australian horticulture, attacking a very broad range of ornamentals, nursery stock, vegetables, fruit crops and some turf-adjacent plantings. It thrives in hot, dry, dusty conditions and populations can build explosively over spring and summer, with reproduction slowing in cool, humid weather.

Management relies on regular monitoring of leaf undersides, maintaining adequate plant moisture and reducing dust and plant stress, since drought-stressed plants are more susceptible to rapid population build-up. Encouraging predatory mites and other natural enemies helps keep populations in check, and broad-spectrum insecticide use should be minimised where possible as it can flare mite numbers by killing beneficial predators. In protected cropping and nursery situations, biological control agents and miticides registered for two-spotted mite are commonly integrated into control programs.