Habits of Red Spider Mites

• Red Spider mites do not spin good webs. Proper spiders make symmetrical and neat webs.
• You can recognise infections if the web is feeble and scraggy with tiny white flecks on some of the strands (this is dead mite skins).
• You can also detect mites by placing white paper under a leaf and tapping several times. If infested some of the mites will fall from their hiding under leaves and away from direct light on to the paper.  If you see red dots scampering around and you have your work cut out although they start green in spring turning red later in the summer.
• Mites pierce the skin of leaves and suck sap causing paling then red or yellow spots. This then leaves a fine white powder and leaves begin to fall off.

Problem Control and Prevention

• Few plants are immune and indoor Cistus, Dracaena, Citrus, Podocarpus and even Aspidistra are susceptible.
• Tomato and greenhouse plants also suffer.
• Crocosomia, dahlia, fuchsia, runner beans and soft fruit are also susceptible.
• Mite move easily from plant to plant and are so small that drafts can blow them from one plant to another. Isolation is the first option.
• Mites find a hot dry environment a delight, whilst mites abhor humid conditions so try frequent misting to discourage mites.
• Submerging plants in a stream of warm water or hosing off out doors may help.
• Spray with soapy water or plant oils paying attention to the undersides of leaves and leave to dry.
• Biological control with Phytoseiulus persimilis is effective in warm areas.
• Malathion pesticide can be used, mix with water and a drop of soft soap but keep the spray away from cacti and ferns.
• Systemic granular pesticide is a last alternative.

Sources
Tetranychus urticae Female of the red form of the spider mite
Scale : mite body length ~0.5 mm
Creative commons by Gilles San Martin, on Flickr
Chuck Crandall ‘Whats wrong with my plant?’

RHS the Tetranychus urticae is also known as Two Spotted Spider Mite