Spider Mites

Spider mites are microscopic, sap-sucking arachnids that are smaller than aphids. To the naked eye, they usually look like moving dots of various colours – red, yellow, or brown. You will need a 10X handheld lens be able to spot them clearly. They have needle-like mouthparts to pierce through plant tissue to feed off the sap.

They usually live in colonies on the underside of leaves in hot, dry and dusty conditions. Colonies can be identified by spotting the pests among white webbing. Plants under water stress are highly vulnerable to spider mites. Leafy vegetables such as bayam, kangkong and various fruiting vegetables like brinjal, chili and cucumber are susceptible to spider mites during the dry season.

As with most pests, spider mites generally attack plants that are already unhealthy. Check your plant for additional problems such as prolonged wilting from heat stress, etiolation, or overcrowding. Cultural control methods should be implemented to prevent your plants from becoming unhealthy in the first place.

Symptoms

Spider mites can be found on young shoots and buds, or on the underside of leaves and on fruits. They appear as tiny red dots to the naked eye.

Affected fruits and leaves may have stippling, which are tiny dots from bite marks.

Infected leaves may appear bronze or yellow, and curled. Affected fruits may have corky tissue.

Webbing is usually present on the surface which spider mites are feeding on.

Preventive and control measures:

Always isolate and inspect newly bought plants for pests before introducing them to your plant collection. Isolate affected plants immediately if pests are found.

Healthy plants are generally resilient to infestations. If you have a severe pest infestation, check your plants regularly for additional underlying problems such as prolonged wilting from heat stress, etiolation, or overcrowding.

If there are only a few spider mites, you can spray them off with water or use a wet cloth to wipe them away.

Heavily infested plant parts should be pruned as soon as possible. Severe infestations may need the entire plant to be removed. Bag up the infested plant or plant parts securely for proper disposal to prevent further spread. Do not use the removed plant waste for composting or for consumption.

Chrysanthemum spray, horticultural oils and sulphur soap sprays can kill soft-bodied pests on contact. Use chemical controls like these sparingly as they tend to also affect other types of biodiversity.