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Pests in Gardens and Landscapes: Quick Tips

Nymph (with lerp removed), eggs, adult, and lerp of eucalyptus lerp psyllid.

Damage caused by eugenia psyllid.

Lerp psyllids on eucalyptus.

Psyllids are aphidlike insects that secrete sticky honeydew. Some species produce white wax, distort leaves and shoots, stunt plant growth, or cause defoliation. Management includes providing proper plant care, conserving natural enemies of psyllids, and applying low-toxicity insecticides when needed. Most plants can tolerate low to moderate numbers of psyllids.

Plants commonly affected include:

• Acacia, boxwood, eucalyptus, eugenia, pepper tree, and some other ornamentals
• Pear, potato, and tomato

Damage resembles that from some aphids, scale insects, and whiteflies. Look for:

• Abundant sticky honeydew that psyllids excrete as they suck plant sap
• Black sooty mold growing on the honeydew
• Curly or powdery wax or, in certain species, crystallized covers called “lerps”
• Distorted or galled leaves or shoots or prematurely dropping foliage

Learn to recognize psyllids.

• Adults are 1⁄10 to 1⁄5 inch long and hold their wings rooflike over their bodies.
• Adults are quite active, often jumping away when disturbed.
• Nymphs are flattened and oblong to round. Some can move, but pit-making species remain stationary.
• Nymphs of several species that feed on eucalyptus are hidden under hardened covers (lerps).

To reduce problems, use an integrated approach.

• Provide plants with appropriate environmental conditions and cultural care, especially proper irrigation; conditions vary for each location and plant species.
• Choose plant species or cultivars that psyllids don’t infest or that are less susceptible to these pests, such as certain acacia and eucalyptus.
• Learn how to recognize and conserve psyllid parasites and predators. Certain psyllids can be controlled by these natural enemies.
• Avoid stimulating succulent growth by reducing fertilization and unnecessary pruning.
• For topiary eugenia, shear growing tips about every 3 weeks and leave the clippings as mulch on the ground for at least 3 weeks to allow beneficial parasites time to emerge.

What about pesticides?

• Don’t treat plants with insecticides unless you have an intolerable psyllid infestation.
• Avoid insecticides that injure natural enemies. Common natural enemies of psyllids include lady beetles, pirate bugs, and parasitic wasps.
• If you must treat, select insecticidal soaps, oils, and other least-toxic products, or use a soil-applied systemic insecticide for especially intolerable problems. Systemic insecticides may be toxic to honey bees and other beneficial insects so avoid using them during bloom.

Minimize the use of pesticides that pollute our waterways. Use nonchemical alternatives or less toxic pesticide products whenever possible. Read product labels carefully and follow instructions on proper use, storage, and disposal.