Chrysoperla carnea
Green lacewing- Rate
- 2–20 /m² per release, weekly
- Temp
- 20–28 °C best; works above a 12 °C average
- Best for
- A minor psylla predator; conserve rather than release
Pest
Pear psylla
Cacopsylla pyricola
The short answer
Pear psylla is a tiny sap-feeding insect, 2–3 mm long, that looks like a miniature cicada and breeds only on pear. Its nymphs live in drops of honeydew. The honeydew runs onto the fruit, grows black sooty mould and russets the skin. Heavy feeding scorches the leaves black and can drop them, and the psylla also spreads pear decline. Control starts before the buds open. The adults spend the winter on the tree, and a white film of kaolin clay sprayed at delayed dormant stops most of them settling and laying eggs. After that, oil sprays and the orchard's own predators keep numbers down.
hero macro · pear psylla nymphs in honeydew on a pear shoot
Cacopsylla pyricola nymphs half-buried in honeydew on a pear shoot, with a winterform adult. Photo: pending.
Identification
Adults hold their clear wings rooflike over the body and look like tiny cicadas. There are two forms. Winterform adults are darker and larger, about 0.125 inch (3 mm; wing length 2.3–2.5 mm), and can look almost black. Summerform adults are about 0.08 inch (2 mm; wing length 1.6–1.8 mm) and reddish-brown with black markings. UC IPM's tell for pear psylla is a dark spot on the top middle edge of each wing.
The eggs are tiny and elongated, like grains of rice, creamy white when laid and yellow to orange as they develop. They are laid on or near the fruit spurs in late winter, then along the midribs and leaf stalks of new leaves. The nymphs pass through five instars. The first is translucent yellow, and four of the five are almost buried in honeydew. The fifth, called the hardshell, is dark green to dark brown with prominent wing pads.
Easily confused with
- Psocids (barklice)HarmlessPsyllids jump when disturbed; psocids run or fly away, and they have a narrower neck and chewing mouthparts.
Damage symptoms
Psylla harms pears in three ways. The honeydew from the nymphs falls onto the fruit, where it russets the skin and grows black sooty mould. The toxin in the nymphs' saliva blackens parts of the leaf blade, yellows the leaves and can defoliate a tree. WSU calls this psylla shock and notes it can cut fruit set the following year. The psylla also injects the phytoplasma that causes pear decline, which starves the roots. How badly a tree suffers depends on the variety, the rootstock, the site and psylla numbers (UC IPM). Trees on Asian pear or Ussurian pear rootstocks are the most susceptible. Trees on European pear, P. betulifolia, P. calleryana or quince tolerate infection. UC IPM notes the psylla is a bigger problem on European pears than on Asian varieties.
- Sticky honeydew on leaves and fruit, dripping from shoots in heavy infestations
- Black sooty mould on the honeydew, and fruit skin marked with dark russet streaks or blotches
- Parts of the leaf blade turning black, as if burnt, then yellowing and dropping
- Stunted shoots and poor fruit set the following year after heavy feeding
- Slow decline of the whole tree on susceptible rootstocks (pear decline)
Lifecycle & degree days
Winterform adults spend the winter in reproductive diapause on or near the tree. They start laying eggs as the pear buds swell, on the wood at the base of the fruit and leaf buds. Their offspring become summerform adults from about mid-May. WSU reports two to four summerform generations in most pear-growing regions, and generally two complete ones in Washington. Each female lays 10–20 eggs at a time (UC IPM). If the overwintered adults lay before they are controlled, the generations overlap, all stages are present at once, and sprays reach only some of them. UC IPM notes that high summer temperatures suppress psylla in California. UC IPM warns that numbers left high through summer and after harvest send adults dispersing in autumn, which makes the next winter's control harder.
- Overwinters
- Winterform adults, in reproductive diapause
- Egg-laying starts
- As buds swell; late January–early February in California
- Generations / yr
- 2–4 summerform generations; generally 2 complete in Washington
- Eggs
- Laid 10–20 at a time (UC IPM)
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Host crops
Pear psylla reproduces only on pear. As they disperse in autumn and return in spring, the adults may feed briefly on apples, conifers and shrubs, but they do not breed there (WSU). European pears suffer more than Asian varieties. Rootstock matters for pear decline: Asian-pear (P. pyrifolia) and Ussurian (P. ussuriensis) rootstocks are the most susceptible, and UC IPM recommends Winter Nelis, Old Home × Farmingdale or P. betulaefolia seedling rootstocks.
Monitoring & action thresholds
Action threshold
No garden threshold
The published thresholds are for commercial orchards. UC IPM aims for no more than 1 adult per 100 beat-tray samples by bud break, then treats at 2 or more flower clusters with eggs per 100 at bloom, or 1 or more infested top shoots per 20 during fruit growth. WSU found that more than 0.4 second- or third-generation nymphs per leaf led to over 2% culled fruit. On a garden tree, the practical point is timing: WSU calls prebloom sprays essential, and the kaolin film goes on from delayed dormant, before the buds break.
Use a beat tray: hold a white tray or cloth about a foot below a branch and tap the branch firmly three times, then count the adults that land. Do this in winter to see how many adults are waiting to lay. From late winter, look at the fruit spurs with a 10× lens for eggs. After bloom, check the youngest leaves on shoot tips, including tips high in the tree, for nymphs, eggs and honeydew. UC IPM's sign that predators are working is one to several nymphs per infested shoot. Without effective predation there are often 10 or more.
Beneficial
Biological control
Pear psylla has a strong set of natural enemies, and broad-spectrum sprays are what break it. UC IPM notes that nonselective sprays for codling moth kill them and cause psylla outbreaks. In Washington, the parasitoid wasp Trechnites insidiosus has parasitised more than 70% of psylla in unsprayed orchards and 50% in organic ones. Predatory bugs do much of the rest. Deraeocoris brevis eats about 200 psylla eggs a day and Campylomma verbasci more than 170 in the lab, and Anthocoris species, relatives of the minute pirate bug, specialise in psyllids. European earwigs are also major predators; young ones have eaten up to 1,000 psylla eggs a day. That is one reason not to fight earwigs in a pear tree. Green lacewings take psyllids less readily than aphids. Neither UC IPM nor WSU suggests releasing any of them for psylla; the aim is to stop killing them.
Cultural controls
The single most useful step for a home pear is a white particle film before the overwintered adults lay. After that, avoid broad-spectrum sprays so the predators build up.
- Spray kaolin clay (Surround WP) at ¼–½ lb per gallon (the label's hand-sprayer rate), three times 7–10 days apart from delayed dormant to green cluster bud; renew the film when it stops leaving white on a dark cloth
- Keep kaolin to the prebloom period and at most two sprays after bloom; later use can set off mite outbreaks (UC IPM, WSU)
- Avoid pyrethroid and other broad-spectrum sprays for codling moth, which wipe out psylla predators
- Summer-prune the vigorous leafy shoots to remove nymphs and honeydew, and let more light and spray into the canopy (WSU)
- Hose honeydew off the fruit when it is heavy (WSU), but not so often that the canopy stays wet
- Choose a tolerant rootstock when planting, and avoid Asian-pear or Ussurian rootstocks in psylla areas
- Do not over-fertilise with nitrogen; soft new growth favours psyllids (UC IPM, psyllids generally)
Chemical, last resort
Broad-spectrum sprays kill psylla predators and bring outbreaks; psylla readily develops resistance. Don't let oil or neem reach open blossoms (bees)Check any product before it goes on. Open the compatibility matrix →
- Narrow-range oilREI 12 h
- Kaolin clay (Surround WP)REI 4 h
- Azadirachtin (neem)REI 4 h
- EsfenvalerateREI 12 h
Rating: the effect on this pest's natural enemies if a spray hits them or they feed on treated plants. REI is the re-entry interval on farm and greenhouse labels; home labels usually give none, so follow the label.
Sources
UC IPM Pest Management Guidelines: Pear — Pear Psylla (text 11/2012; table 02/2025)
UC IPM, Relative Toxicities of Insecticides Used in Pears to Natural Enemies (11/2012)
WSU Extension FS376E, Pear Psylla Integrated Pest Management (DuPont et al., May 2022)
EPA-accepted label, Surround WP Crop Protectant, EPA Reg. 61842-18 (Dec 2019)
Puterka, Glenn & Pluta, J. Econ. Entomol. 98:2079, 2005 — particle films and pear psylla
Nottingham, Orpet & Beers, J. Econ. Entomol. 115:1607, 2022 — kaolin-based IPM programs
UC IPM, Psyllids (Home and Landscape Pest Notes)
Page status
Drafted from the sources below, then checked claim by claim against those sources on 23 September 2026.
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