Glasshouse red spider mite is a common sap-feeding mite that can cause mottled leaves and early leaf loss on a wide range of greenhouse and garden plants. It is also known as two-spotted spider mite.
Common name Glasshouse red spider mite or two-spotted spider mite
Plants affected Many greenhouse and garden plants, and houseplantse
Symptoms Mottled foliage and early leaf fall
Active March to October
Glasshouse red spider mite can be one of the most troublesome problems of greenhouse plants and houseplants. It can also attack garden plants during summer. It is a sap-sucking mite that attacks the foliage of plants, causing a mottled appearance, and in severe cases, leaf loss and plant death.
It attacks a wide range of houseplants and greenhouse plants, both ornamentals and edibles, including: vines, peach, nectarines, cucumbers, tomatoes, aubergines, peppers, Fuchsia, Pelargonium, poinsettias, orchids and Impatiens. The host range of this mite is so wide that few plants are completely immune.
Glasshouse red spider mite thrives in warm, dry conditions, and is usually only a problem from March to October, but damage can occur at other times in a heated greenhouse. It can also cause problems outdoors in summer, especially in hot, dry weather.
You may see the following symptoms:
On leaves: Plants infested with glasshouse red spider mite show a fine pale mottling on the upper leaf surface. The underside of the leaves have many tiny yellowish green mites and white cast skins and egg shells. These are more easily seen with the aid of a x10 hand lens
On plants: In heavy infestations, you may see fine silk webbing on the plants, and the leaves lose most of their green colour and dry up or fall off. Heavily infested plants are severely weakened and may die
Environmental Control: Red spider mites thrive in dry, warm conditions. Increasing humidity can deter their growth. Regular misting of plants, especially in hot weather, can be effective.
Regular Inspection: Check your plants frequently for signs of infestation, particularly on the undersides of leaves.
Quarantine New Plants: Before introducing new plants into your garden or indoor space, quarantine and inspect them to ensure they are mite-free.
Cleanliness: Keep the area around your plants clean and free of dust. Remove any dead or decaying plant matter promptly as it can attract mites.
Encourage Beneficial Insects: Predatory mites, ladybugs, and lacewings are natural enemies of spider mites. Encouraging these beneficial insects can help control the mite population.
Water Sprays: A strong jet of water can help dislodge and remove mites from the plant. This is a simple, non-chemical approach suitable for mild infestations.
Insecticidal Soap or Horticultural Oil: These are effective against mites and are less harmful to beneficial insects and the environment than synthetic pesticides. They work by suffocating the mites.
Neem Oil: Neem oil is a natural pesticide that can deter spider mites. It disrupts their life cycle and prevents them from feeding.
Biological Control: Releasing predatory mites or other natural predators can help control the spider mite population.
Chemical Pesticides: If the infestation is severe, chemical pesticides may be necessary. However, spider mites can develop resistance, so these should be used as a last resort and according to the manufacturer's instructions.
Regular Monitoring: After treatment, continue to monitor your plants regularly for any signs of re-infestation.
Important Notes
Test Sensitivity: Before applying any treatment, especially chemical ones, test it on a small part of the plant and wait 24-48 hours to check for adverse reactions.
Rotation of Treatments: If you need to treat repeatedly, rotate between different types of treatments to prevent resistance.
Integrated Pest Management (IPM): Utilizing a combination of methods (cultural, mechanical, biological, and chemical) is often the most effective way to manage pest problems.
Remember, the key to controlling red spider mites is early detection and consistent monitoring. Regular care and attention to your plants are vital in preventing infestations.
Ingredients: Mild liquid soap (like dish soap) and water.
Recipe: Mix about 2 teaspoons of soap with a liter of water.
Application: Spray the solution directly on the affected areas of the plant, especially under the leaves. Repeat every few days until the mites are gone.
Ingredients: Neem oil and water.
Recipe: Add a few drops of neem oil to a liter of water. You can also add a little bit of mild liquid soap to help emulsify the oil.
Application: Spray liberally over the plant, ensuring you cover all areas where mites might hide. Neem oil not only kills mites but also helps prevent them.
Ingredients: Garlic cloves or onions, water.
Recipe: Blend a couple of garlic cloves or one onion with two cups of water. Strain the mixture and use the water.
Application: Spray on the plants. The strong smell can deter mites and other pests.
Ingredients: Hot pepper (like cayenne), water, and a little soap.
Recipe: Mix a tablespoon of ground hot pepper with a liter of water and a few drops of liquid soap.
Application: Spray on affected areas. The capsaicin in the pepper is a natural deterrent.
Ingredients: Rubbing alcohol and water.
Recipe: Mix equal parts of alcohol and water.
Application: Use a spray bottle to apply it to infested areas. Alcohol can dehydrate and kill mites.
Important Tips
Test First: Before applying any homemade treatment, test it on a small part of the plant first to ensure it doesn’t cause damage.
Regular Application: You might need to apply these treatments several times, every few days, to effectively control the mite population.
Thorough Coverage: Make sure to spray the underside of the leaves where mites commonly reside.
Avoid Strong Sunlight: Apply these sprays during the cooler parts of the day to prevent leaf burn.
While homemade treatments are generally safer than chemical pesticides, they can still harm some plants, especially if used excessively or in very strong concentrations. Always observe your plants' reactions after the initial application.