Red Spider Mite
Red Spider Mite, Two Spotted Spider Mite
Tetranychus urticae, or red spider mite, is a tiny red arachnid, belonging to the Acari (mite) family, known as Tetranychidae. Mites are close relatives of ticks and spiders. They're barely visible with the naked eye. A tip to see if they are present on plants is to look for tiny, dusty cobwebs. In front of a light, they are easier to spot. They're common pests of greenhouse plants, where temperatures are warmer. They also are a frequent and annoying pest of houseplants. They have a broad host range, feeding on anything to vegetables, fruits and ornamental plants such as roses.
Sucks plant cells from plants, resulting in yellow mottling and reduced photosynthesis.
Adult: They're extremely small, yellowish-green or red-brown mites that you can barely see with the naked eye, hence they're fairly tricky to diagnose. The key is to monitor the plant symptoms. They measure below 0.4mm in length.
Fine, dusty webbing on foliage. Yellow mottling on leaves. Leaf yellowing. Dried up leaves. Premature leaf fall. Loss of vigour.
Raise humidity and ventilate glasshouses to increase air movement as this pest thrives in low humidity and high temperatures with little air movement. Within a heated glasshouse, year-round the predatory mite Phytoseiulus persimilis may be used as a form of biological control. It is very effective as it consumes spider mites at all stages of their life cycle. Likewise, predatory ladybugs or lacewing love to eat spider mites. If you see any in your garden, help them out and pop them on your infested greenhouse plants.
Bioneem / Biocure soprays are effective. However, there are many alternative and less harmful methods of control. If a chemical option is sought, check with your local garden centre and please take care to follow the manufacturers' instructions. Check with your local regulating body for guidance on active ingredients and their authorisation for use. Insecticidal soaps may be the next step following the above methods.