Red Spider Mite, Tetranychus urticae

What are those tiny mites killing my tomatoes and cucumbers?

Red spider Mites, also known as two-spotted Mites, are tiny, about 1mm long, with four pairs of legs. If you are a gardener they will be well known to you as they are common pests in greenhouses, conservatories and even indoors on house plants. They prefer hot dry conditions, so the modern centrally heated house makes a nice home for them. Typically they are found as pests of cucumbers and tomatoes. In the tropics they also attack eggplant, castor bean, cotton, citrus and roses.

The red spider mite is only red in winter when hibernating. In fact they are usually yellowish-green in colour with two dark patches, one on each side of the body. They feed on the underside of leaves, sucking the plant's juices. As a result the leaves become speckled with pale spots. If the numbers increases, fine threads of webbing appear, often near the top of the infected plant. It is not so much the sucking that damages or kills a plant but rather the viruses the mite injects into the plant as it feeds. Plants turn yellow and then brown before the leaves drop and the plant dies. Under ideal conditions, a female can lay 4-8 eggs each day for about three weeks. The young that hatch are capable of breeding in just a few days.

Red Spider Mites can be controlled by the use of predatory mites, such as Phytoseiulus persimilis, which eat up to 7 spider mites each day. Propriety pesticides can be purchased through hardware shops and garden centres. For do-it-yourself control, chilli, garlic and soap extracts mixed with milk and flour can be used.

Share on social media: