How to Recognise and Control Mealybugs on Citrus Trees
Jan 12, 2025
Mealybugs are small (3-6mm), oval, soft-bodied sap-sucking insects that are often covered in a white, cottony substance. They can be a serious pest of citrus trees, causing stunted growth, leaf yellowing, and reduced fruit quality.
Main Types of Mealybugs
The most common mealybug species found on citrus include:
- Citrophilus mealybug (Planococcus citri)
- Long-tailed mealybug (Pseudococcus longispinus).
Photo Above: Long-tailed Mealybug
Damage Symptoms
- Leaf Yellowing and Curling: Mealybugs pierce plant cells with their mouthparts and extract sap. This can cause leaves to become distorted, yellow, or stunted.
- Honeydew production: Like aphids, mealybugs secrete a sticky substance called honeydew. This can attract sooty mould growth on leaves and fruit. This can reduce photosynthesis and make the fruit unsightly.
- Fruit Damage: Infestations can result in poor fruit quality, drop, or deformation.
- Reduced Vigor: Heavy infestations can weaken the tree, making it more susceptible to other pests and diseases.
Photo Above: Citrophilus Mealybug
Control Strategies
- Regular pruning to remove dead or diseased branches. This reduces hiding places for mealybugs and improves air circulation and light penetration, which can help reduce mealybug populations.
- Regularly check the undersides of leaves and around the base of stems for signs of mealybugs, particularly during warm months.
- Avoid excessive fertilization: Excessive nitrogen can promote mealybug growth.
- Encourage Beneficial Insects: Promote natural predators like ladybugs, lacewings, and parasitic wasps, which can help control mealybug populations. Plant flowers that attract beneficial insects near citrus trees such as members of the Aster and Parsley families, sweet alyssum, and verbena.
- Manual Removal: For small infestations, mealybugs can be removed by hand using a cotton swab dipped in alcohol
- Introduce natural enemies: If mealybug populations are high, consider introducing beneficial insects to control them. One of several places they can be bought from is Bioforce. https://www.bioforce.co.nz/
- Use organic insecticides: Products based on neem oil and insecticidal soap can be effective against mealybugs.
Photo Above: Sweet Alyssum Attracts Lacewing, a Natural Predator
