Psyllids
Also known as Jumping plant lice, Psylloidea, Asian citrus psyllid (Diaphorina citri)
In short
Psyllids are small, jumping sap-feeders, and each species feeds on one plant or a close group of plants. Nymphs produce honeydew and wax, and can curl, pit or gall the leaves. The Asian citrus psyllid is the most serious because it spreads citrus greening disease (huanglongbing).
How it looks
Adults are about 2.5–5 mm (1/10–1/5 in) long, with short antennae and wings held roof-like over the body; they jump and fly readily when disturbed. Nymphs are flattened, oblong to round and scale-like, and some species stay in one spot while feeding. Some species make lerps, small hardened covers of wax and dried honeydew that shelter the nymph and help identify the species.
Signs
Sticky honeydew and sooty mould; white waxy secretions; curled, distorted or galled leaves; pitted leaves (eugenia and pepper tree psyllids); stunted new growth and early leaf drop. The tomato/potato psyllid causes yellowing and distorted leaves.
Life cycle
Five nymphal stages before the adult. Most species have three to five generations a year, and numbers peak with flushes of new growth.
What favours it
Flushes of tender new growth, which frequent shearing and heavy nitrogen feeding encourage. The Asian citrus psyllid originates in Asia and is an introduced pest in other citrus-growing regions.
Prevention
- Choose plants less susceptible to local psyllids.
- Water deeply and infrequently, keep nitrogen fertiliser moderate and avoid frequent shearing, which triggers new flushes.
- Inspect new growth regularly and use yellow sticky traps to track adults.
Treatment
Start with the first step and move down only if the problem persists.
- Prune off infested shoot tips.
- Protect natural enemies: ladybirds, lacewing larvae, predatory bugs and parasitoid wasps keep many psyllids under good control.
- Early in the season, spray insecticidal soap or neem oil; follow the product label.
- Spinosad is another option, but it is toxic to bees and some natural enemies for about a day after spraying, so never apply it to plants in flower; follow the product label.
- Systemic neonicotinoid-class products are for severe infestations only; they harm pollinators and natural enemies, so follow the product label.
Pros and cons
Cons
- The Asian citrus psyllid spreads citrus greening (huanglongbing), and the tomato/potato psyllid is linked to zebra chip disease of potato.
- Honeydew, sooty mould and wax dropping onto surfaces below.
Look-alikes
- Aphids
- Have cornicles on the rear, do not jump, and produce live young in dense colonies.
- Leafhoppers
- Larger and wedge-shaped; nymphs run sideways rather than sitting flat like scales.
- Whiteflies
- Adults have white waxy wings and fly up in clouds.
Affected plants
Each species is host-specific: citrus, eugenia, acacia, boxwood, eucalyptus, pepper tree, pear, tomato and potato all have their own psyllids.
Related
Sources
Written in our own words from these sources. Check a product label before using any treatment.