Two-Spotted Spider Mite

The mites are tiny, roughly the size of a grain of dust, and are best seen with a hand lens as pale, greenish to yellowish, oval creatures with two darker spots on the body. They cluster on the underside of leaves and, when abundant, spin fine silk webbing that can cover leaves and shoot tips.

Early damage appears as fine pale stippling on the upper leaf surface; heavier feeding bronzes and dries the foliage, and webbing becomes obvious. Tapping leaves over white paper to dislodge moving mites is a simple way to detect and confirm them.

Development from egg to adult is very rapid in warm weather, so populations can build explosively over a short period. Mites disperse by crawling and by ballooning on silk threads in wind, and they move readily on equipment, workers, and plant material. In cool conditions some females enter a dormant, often reddish, overwintering state.

Because generations are so short, resistance to miticides can develop quickly where the same products are used repeatedly, and outbreaks are frequently triggered when broad-spectrum sprays remove the predatory mites that normally keep the pest in check.

Cell-by-cell feeding reduces photosynthesis and, at high densities, bronzes, dries, and prematurely drops leaves, which can reduce yield and fruit quality. Hot, dry, and dusty conditions and drought stress make plants more vulnerable and speed mite build-up. Damage varies widely with crop, weather, and the presence of natural enemies.

The host range is very broad and includes common bean, strawberry, tomato, and cucumber among many field, vegetable, orchard, and greenhouse crops. Protected cultivation is often especially favourable to the mite.

Monitoring uses a hand lens to inspect the underside of leaves for mites, eggs, stippling, and webbing, and the paper-tap method to detect moving mites, with attention to hot spots and drought-stressed areas. Checking for predatory mites alongside the pest helps judge whether natural control is keeping pace before deciding to intervene.

Management centres on conserving predatory mites, reducing plant stress, and using selective tools within integrated pest management, because broad-spectrum sprays often make mite problems worse.

• Conserve and, in protected culture, release predatory mites and other natural enemies
• Reduce plant stress by maintaining adequate irrigation and managing dust along field edges and roads
• Avoid broad-spectrum insecticides that flare mite populations by killing predators
• Rotate among selective miticide modes of action to slow resistance where treatment is needed
• Base any intervention on lens-based scouting and the ratio of mites to predators