Asian Citrus Psyllid

Diaphorina citri

This entry covers Asian Citrus Psyllid (Diaphorina citri) as a species-level regulated citrus vector. It is most relevant on young citrus flush, nursery liners, rootstocks, and mature citrus trees. The operational concern is distorted new growth and, far more importantly, transmission of the bacterium associated with huanglongbing; killing psyllids does not cure infected trees. Recognition should begin with mottled brown adults that feed at a head-down angle and flattened yellow-orange nymphs that produce conspicuous white waxy tubules on tender flush.

Identification

Taxonomy and field characters. Asian Citrus Psyllid is listed as Diaphorina citri. It should be classified as a species-level regulated citrus vector. Diagnostic attention belongs on young citrus flush, nursery liners, rootstocks, and mature citrus trees. The most useful field characters are mottled brown adults that feed at a head-down angle and flattened yellow-orange nymphs that produce conspicuous white waxy tubules on tender flush. Host association is often decisive. Natural enemies can be mistaken for pests: parasitoid mummies, lacewing larvae, lady beetle larvae and predatory bugs should be recorded before any treatment.

Symptoms / Signs

Fresh injury may include distorted new growth and, far more importantly, transmission of the bacterium associated with huanglongbing; killing psyllids does not cure infected trees. Vector records require a second diagnostic track: plant disease symptoms may remain after vectors leave, and suppressing the insect does not cure infected plants. Distribution adds evidence.

Life Cycle / Process

Eggs are laid only on very young flush. Five nymphal instars remain on tender growth, while adults move among trees and can survive between flush cycles. Eggs and settled nymphs may remain hidden on young growth or leaf undersides, while winged adults reveal movement but not the density already established on foliage.

Prevention

Begin with clean, traceable plants and inspect the host tissue favored by Asian Citrus Psyllid before material enters propagation, greenhouse or retail areas. Keep scouting routes consistent and inspect newly expanding flush for eggs and nymphs, tap foliage over a white surface for adults, and follow current Florida citrus survey and movement requirements.

Management / Control

Confirm identity before selecting a tactic. Inspect newly expanding flush for eggs and nymphs, tap foliage over a white surface for adults, and follow current florida citrus survey and movement requirements. Intervention is justified when a crop-specific threshold is exceeded, marketable tissue is being contaminated, colonies are expanding despite natural enemies, or a confirmed vector threatens a susceptible crop. Begin with protect clean nursery stock with exclusion and certified material, coordinate flush scouting, conserve Tamarixia radiata where compatible, and follow current citrus-production and FDACS guidance for labeled insecticides and resistance rotation.

Procedure Steps

1. Map the affected crop, host species, cultivar and production zone; photograph fresh symptoms before disturbing the colony. 2. Collect adults and immatures from young citrus flush, nursery liners, rootstocks, and mature citrus trees and confirm mottled brown adults that feed at a head-down angle and flattened yellow-orange nymphs that produce conspicuous white waxy tubules on tender flush. 3. Establish a baseline: inspect newly expanding flush for eggs and nymphs, tap foliage over a white surface for adults, and follow current Florida citrus survey and movement requirements. 4. Reinspect the same plants or traps within one generation interval and again after new growth appears; escalate to a diagnostic laboratory if identity or vector status remains uncertain.

Safety Notes

Avoid exposing workers, visitors, pollinators or food-contact surfaces to unnecessary sprays. When Asian Citrus Psyllid occurs on edible crops, verify preharvest and restricted-entry intervals; when it occurs in greenhouses, confirm that enclosed-space use is expressly allowed. For vector records, isolate suspect plant material and follow current diagnostic or regulatory guidance rather than moving it through the nursery.