Mealybugs are common garden pests that can quickly infest and damage outdoor plants. Getting rid of mealybugs requires persistence and using a combination of control methods. Here is a comprehensive guide on how to effectively get rid of mealybugs on outdoor plants.
Identifying Mealybugs
Mealybugs appear as small, soft-bodied insects that are oval-shaped and covered with a white waxy coating. They tend to cluster together in hidden spots on plants, especially on the undersides of leaves, stems, and where leaves join stems.
Signs of a mealybug infestation include:
- White waxy deposits on leaves and stems
- Clusters of small, soft-bodied insects
- Stunted or distorted plant growth
- Leaf yellowing or wilting
- Honeydew or sticky residue on plants
- Ants frequenting plants due to honeydew deposits
Closely inspect plants to confirm the presence of mealybugs before taking any control measures. Focus on crevices and hidden areas where they congregate.
Non-Chemical Control Methods
Use a Strong Jet of Water
Blast plants with a strong jet of water to dislodge mealybugs and expose them to natural predators. Be sure to spray underneath leaves and deep into crevices where they hide. Repeat every few days until mealybug populations are under control.
Apply Horticultural Oils
Horticultural oils smother mealybug bodies and eggs. They are safe for outdoor use on plants. Thoroughly coat all plant surfaces, including the undersides of leaves. Reapply every 7-10 days until mealybugs are gone.
Use Alcohol Sprays
Spraying 70% isopropyl alcohol directly on mealybugs will kill them on contact. Be sure to fully saturate bugs and eggs. Repeat treatment every 3-5 days until pests are gone. Alcohol sprays work best on houseplants or small outdoor container plants.
Apply Insecticidal Soap
Insecticidal soaps dissolve the waxy coating on mealybugs, causing dehydration and death. Spray all plant surfaces, especially the undersides of leaves, according to label directions. Reapply every 5-7 days until mealybug elimination.
Release Natural Predators
Natural predators like ladybugs and lacewings will feed on mealybugs. Attract these beneficial insects to your garden with companion plants. Releasing store-bought ladybugs around infested plants can also help reduce pest numbers.
Prune Heavily Infested Parts
Cut away severely infested stems, leaves, and plant parts. This can eliminate large colonies of mealybugs. Be sure to dip pruning shears in alcohol between each cut to avoid spreading pests. Destroy all infested clippings.
Apply Diatomaceous Earth
Sprinkle diatomaceous earth onto plants and into crevices where mealybugs hide. The sharp particles cut insect bodies, causing dehydration. Reapply after rain or watering. Avoid use on new plant growth. Wear a mask when handling.
Chemical Control Options
If non-chemical methods are ineffective, consider using an outdoor-approved insecticide as a last resort:
- Neonicotinoids – Systemic insecticides like imidacloprid move through the plant and kill sucking insects for an extended period. They can harm pollinators, so use judiciously.
- Pyrethroids – Broad spectrum insecticides like bifenthrin provide quick knockdown of mealybug populations. Avoid applying when pollinators are active.
- Horticultural Oils – Dormant oil sprays applied in early spring can smother overwintering mealybugs. Monitor for phytotoxicity.
Always follow label directions when using insecticides. Minimize harm to pollinators and natural predators by applying selectively and only when mealybugs are most vulnerable, such as early in the day or later afternoon. Never apply insecticides to plants in bloom.
Prevention Tips
- Inspect new plants thoroughly before bringing them home
- Quarantine new plants away from existing plants for a few weeks
- Dispose of heavily infested plants when possible
- Avoid excess fertilization which encourages mealybug growth
- Control ants which spread mealybugs
- Monitor regularly for signs of infestation
- Clean up dropped leaves, debris, and weeds where mealybugs may live
- Use a row cover, mesh, or netting to exclude pests
Conclusion
Mealybugs can be persistent pests but there are many effective control options available. Combining methods such as horticultural oils, insecticidal soaps, alcohol sprays, natural predators, and insecticides when necessary can help eliminate outdoor mealybug infestations. The key is thorough coverage, repeat applications, and persistence. Prevention is also vital to avoid introducing and spreading mealybugs in the garden. With diligence and using multiple integrated pest management techniques, you can successfully get rid of mealybugs on outdoor plants.