Despite their name, red spider mites – also referred to as greenhouse or glasshouse spider mites or two-spotted mites – are more commonly yellow, orange, green or brown!
Red spider mites are sap suckers, feeding on all above ground parts of plants, but especially leaves, stems, fruit and any other relatively soft part of the plant.
Although most commonly seen on plants growing indoors in warm, dry conditions, red spider mite will also attack numerous outdoor plants, especially during hot, dry summers.
Individually, they are almost impossible to see with the naked eye – you need a good hand lens to spot them – measuring around 1mm.
The orangey-red, mature females may spend the winter away from plants in cracks and crevices in walls, greenhouse frames, and just about anywhere else, including plant debris. In early spring, they find a suitable host plant and start laying eggs.
As numbers build up to heavy infestations, the mites’ characteristic silky webbing is seen on leaves and stems. This is often the first thing many people see – by which time a lot of damage has already been done. This is accompanied by shed dead skins and eggs.
The webbing is often confused for a household spider web. Large, red mites often seen in summer walking over walls and paths are scarlet mites, and do not attack plants.