Pear Psylla

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PestControlBasics Editorial Team

Reviewed by Derek Giordano · Updated 2026

Illustrated identification guide — PestControlBasics.com

🔍 Identification

Adults: 2-3mm; resembles a winged aphid; summer form dark reddish-brown; winter form lighter. Nymphs: flat; oval; found on leaf undersides and shoot tips; surround themselves in honeydew droplets. Damage: massive honeydew production leading to sooty mold covering leaves, fruit, and branches; direct feeding damage causing premature leaf drop; phytoplasma transmission causing 'pear decline' — a fatal vascular disease.

🧬 Biology & Behavior

Four to five generations per year. Adults overwinter on pear bark. Eggs laid on bark and buds in late winter — the dormant oil spray targeting overwintering adults in late winter/early spring is the most impactful single treatment. Nymphs feeding in spring are most susceptible to treatment. By summer, honeydew and sooty mold accumulation creates the visual alarm that often prompts treatment — but earlier, lighter treatment is far more effective.

⚠️ Damage & Health Risk

Massive honeydew and sooty mold accumulation; phytoplasma-mediated pear decline (fatal); premature leaf drop; fruit russet and contamination; economic losses in commercial pear production.

🔧 DIY Treatment

Dormant oil spray in late winter (February-March) at 2% targeting overwintering adults on bark. Kaolin clay on young shoots in spring deters egg-laying. Insecticidal soap on nymph colonies. Spirotetramat (Movento) systemic treatment for severe infestations.

👷 When to Call a Pro

Commercial pear: degree-day guided spray program starting with dormant oil and continuing with insecticidal soap or spirotetramat through the season.

❓ FAQ

When should I spray for pear psylla?

Late winter dormant oil application (February-March, before bud swell) is the highest-impact timing — it kills overwintering adults that would otherwise produce 4-5 generations. Combine with kaolin clay starting at bud break. If you miss the dormant window, insecticidal soap on nymph colonies in April-May is the next best option.

What is pear decline disease?

Pear decline is caused by a phytoplasma pathogen transmitted by pear psylla feeding. Infected trees show premature leaf drop in fall, red fall color, reduced vigor, and eventual decline and death over several years. There is no cure — the tree must be removed. Managing pear psylla populations is the only prevention. Infected rootstocks are particularly susceptible.

🐛 Pear Psylla