Post category: Red spider mite


Red spider mites are very tiny mites, just visible to the naked eye. Cucumber, melons, peppers, peaches, apples, strawberries, datura, blackeyed susan, busy lizzie and ageratum seem to be especially attractive but more or less any plant can be attacked, even potatoes. Outdoor plants can be affected.

The sap-sucking of thousands of mites causes stunting and yellowing of plant leaves, which often fall off. The most obvious symptom is small, yellow flecks on the upper surface of the leaf, although the pest feeds beneath. Very fine webbing can also be detected when there is a heavy infestation.

Control is difficult to achieve. Be careful to avoid buying plants that are infested. Healthy, strong plants are fairly resistant, so feed and water indoor plants properly. Spraying twice a day with clear water helps to control the mites but this may not be practical. Outdoors, the mites have many predators, usually becoming troublesome only in warm summers.

There is a very efficient predatory mite that may be introduced to control the pest in greenhouses. The predator can be ordered form garden centres for delivery by post. Reasonably good control can be obtained by spraying with a 5% solution of vegetable oil in water, dispersed with a few drops of washing up liquid. The oil coats the mites and makes movement difficult; the application will need to be repeated.

If colonies begin to build up, indoors or outdoors, a spray of a general garden insecticide gives some control but might need to be repeated.

Some of these sprays can damage certain plants so test them on a few leaves first. Also, red spider mite has built up resistance to certain chemicals, in some places. Sprays cannot be used in conjunction with the predator.