Mealybug
Cryptolaemus + parasitoids.
Mealybug control focuses on beetle releases and hotspot treatment...
About Mealybugs
Mealybugs are a major pest of ornamentals, protected edible crops and houseplants across UK horticulture. These soft-bodied insects hide in leaf axils, stems and roots, feeding on plant sap and producing large quantities of sticky honeydew. Their waxy coating protects them from sprays, making biological control a critical part of any long-term management strategy.
Symptoms of Mealybug Damage
- White, cotton-like clusters on stems, leaf joints and undersides
- Sticky honeydew on leaves and benches
- Sooty mould growing on honeydew deposits
- Distorted growth and reduced vigour
- Root mealybugs causing slow establishment and yellowing
- Presence of small, wax-coated insects and egg masses
Why Biological Control Works
Mealybugs have multiple life stages that are vulnerable to predators and parasitoids. Biological agents can access the tight spaces mealybugs occupy, where chemical sprays often fail. Cryptolaemus montrouzieri (the “mealybug destroyer”) is highly effective against hotspots, while parasitoids such as Leptomastix dactylopii and Anagyrus vladimiri provide excellent long-term suppression when used preventatively in warm environments.
Common UK Mealybug Species
- Pseudococcus viburni (Viburnum mealybug)
- Pseudococcus longispinus (Long-tailed mealybug)
- Planococcus citri (Citrus mealybug)
- Rhizoecus spp. (Root mealybugs)
IPM Recommendations
- Introduce parasitoids preventatively in warm glasshouse crops
- Release Cryptolaemus into hotspots for rapid knockdown
- Avoid over-fertilising with nitrogen, which encourages soft growth
- Improve airflow around plant canopies and reduce excess humidity
- Isolate and treat heavily infested plants promptly
- Use yellow sticky cards to monitor flying male mealybugs
Preventative vs Curative Strategy
Preventative: Release parasitoids such as Leptomastix and Anagyrus early in the crop cycle when temperatures are above 18–20°C. These species establish well in ornamental crops and provide long-term control.
Curative: Deploy Cryptolaemus montrouzieri adults or larvae directly onto mealybug clusters. They are highly mobile and quickly locate infestations, making them ideal for cleaning up hotspots in conservatories, citrus, tropicals and ornamentals.
Environmental Notes
- Cryptolaemus performs best at 22–28°C and is slower below 18°C
- Parasitoids require stable warm conditions for best establishment
- Root mealybugs need soil-based biologicals such as entomopathogenic fungi or nematodes
- Dense canopies can hide infestations — regular inspection is essential
Biological Controls for Mealybug
The options below are examples of beneficial insects and biological products commonly used against mealybug. Always refer to supplier guidance and product labels for crop safety and local registration status.
Cryptolaemus montrouzieri
Product: Cryptoline
Environment: glasshouse
Temperature Range: 18.0 – 30.0°C
Rate: 2–10 beetles/m² depending on infestation level
Frequency: Re-release after 2–3 weeks as needed
Classic mealybug predator; performs best in warm, long-season crops. Avoid broad-spectrum insecticides.
Chrysoperla carnea
Product: Chrysoline
Environment: glasshouse
Temperature Range: 18.0 – 30.0°C
Rate: 5–10 larvae per hotspot plant
Frequency: Repeat 2–3 weekly
Lacewing larvae contribute to mealybug suppression, especially on soft plant tissue.
Anagyrus pseudococci
Product: Anagline
Environment: all
Temperature Range: 18.0 – 30.0°C
Rate: 1–2/m²
Frequency: introduce early; repeat at intervals during pressure
Primary parasitoid for mealybug control. Best introduced early; compatible with Cryptolaemus and good monitoring.
Steinernema feltiae
Product: Exhibitline Sf
Environment: all
Temperature Range: 12.0 – 30.0°C
Rate: 0.5–1 million/m² (via drench)
Frequency: repeat at 7–14 day intervals as needed
Soil drench targeting root-zone stages; keep substrate moist for several days post-application. Combine with hygiene and hotspot management.
Cryptolaemus montrouzieri
Product: Cryptoline
Environment: all
Temperature Range: 18.0 – 30.0°C
Rate: 2–10 beetles/m² depending on infestation level
Frequency: introduce early; repeat during pressure
Predatory beetle for mealybug hotspots; performs best in warmer crops. Pair with nematode drenches for a layered programme.
Anagyrus pseudococci
Product: Anagline
Environment: all
Temperature Range: 18.0 – 30.0°C
Rate: 1–2/m²
Frequency: introduce early; repeat at intervals during pressure
Parasitoid targeting exposed mealybug stages; use alongside soil drenches (Sf) and Cryptoline for integrated control.
Related Biological Solutions
Growers dealing with mealybug often also monitor these pests as part of a complete IPM programme: