What is a spider mite? - briefly
Spider mites are minute arachnids that pierce plant cells to extract sap, often producing stippled foliage and fine silk webs. Their rapid reproduction can lead to serious damage in many agricultural and ornamental species.
What is a spider mite? - in detail
Spider mites are tiny arachnids belonging to the family Tetranychidae, commonly found on the undersides of plant leaves. Adults measure 0.2–0.5 mm, possess a flattened body, and display two pairs of legs. Their coloration ranges from green and yellow to red, depending on species and diet.
The life cycle includes egg, larva, protonymph, deutonymph, and adult stages. Females lay 40–100 eggs on leaf surfaces; development time varies with temperature, from a few days at 30 °C to several weeks at cooler temperatures. Multiple generations can occur within a single growing season, enabling rapid population expansion.
Feeding involves piercing plant cells with stylet-like mouthparts and extracting sap. This activity removes chlorophyll, causing stippling, yellowing, and eventually leaf bronzing. Heavy infestations may lead to leaf drop, reduced photosynthetic capacity, and lower crop yields.
Key identification cues:
- Fine webbing on leaf undersides or between stems.
- Minute moving specks that appear as moving dots.
- Distinctive elongated, oval-shaped bodies when observed under magnification.
Spider mites thrive in warm, dry environments and are prevalent in greenhouse production, ornamental horticulture, and field crops such as strawberries, beans, and citrus. Their dispersal occurs via wind currents, human handling of plant material, and movement of infested debris.
Management strategies focus on prevention, monitoring, and control:
- Cultural tactics – maintain optimal humidity, avoid excessive nitrogen fertilization, and rotate susceptible crops.
- Biological agents – introduce predatory mites (e.g., Phytoseiulus persimilis), beetles, or lacewings that consume spider mite stages.
- Chemical options – apply miticides with different modes of action to deter resistance, following label rates and re‑entry intervals.
- Mechanical measures – spray foliage with strong water jets to dislodge mites and webbing, and prune heavily infested foliage.
Resistance development is a documented concern; rotating active ingredients and integrating non‑chemical tactics reduce selection pressure. Regular scouting, using a 10× hand lens or a portable microscope, enables early detection and timely intervention.