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How to identify it
- The female's scale cover is flat and circular to oval, about 1.5 to 2.6 mm (roughly 1/16 to 1/10 inch) across, and yellow, yellowish-brown or off-white, often with a small transparent to brown spot near the center where the shed skins sit.[1][2]
- Male covers are smaller and elongate-oval, with the shed skin near one end. Adult males have wings.[1][2]
- Under the cover, the adult female's body is yellow, as are the eggs and crawlers. It swells somewhat with age but never becomes kidney-shaped, a primary field character separating it from the other three Aonidiella species in Florida.[1][2]
- Look on leaves, fruit, stems and the bases of palm fronds; it also settles on branches, shoots and trunks.[1][2]
Look-alikes
| Look-alike | How to tell them apart |
|---|---|
| California red scale | Mature California red scale females are kidney-shaped under the cover; oriental scale females are not.[1] |
| Yellow scale and Aonidiella taxus | These Florida Aonidiella species also become kidney-shaped at maturity, unlike oriental scale.[1] |
| Chrysomphalus scales | Inexperienced identifiers can confuse oriental scale with Chrysomphalus species such as dictyospermum scale; a slide-mounted specimen examined under a microscope settles the identification.[2] |
Where it lives
It now occurs in about 72 countries in tropical and subtropical regions, carried by the movement of infested plants, and it also shows up in greenhouses in cooler regions. In the United States it is known to be established only in Florida.[1][2]
Biology and life cycle
It feeds on an enormous range of plants: at least 189 genera in 77 plant families worldwide, almost anything except conifers. In Florida palms are the usual hosts. Half of the state's reports from 2006 to 2025 were on coconut palm, and royal, areca, triangle, date and cabbage palms, hibiscus, frangipani and figs are also common hosts.[1][2]
One study found that reproduction is most often by live birth, though egg laying has also been seen, and UF puts a female's lifetime output at about 200 eggs. Eggs hatch in 2 to 3 days at about 68 F and in 7 to 9 hours at 86 F.[2][1]
The legged first-instar crawlers spread the infestation. They walk perhaps a yard on their own, but wind, other insects, birds and the movement of infested plants carry them much farther.[2][1]
At 77 F a female takes about 44 days from crawler to producing her own first crawlers; males reach adulthood in about 19.5 days.[1][2]
Population densities peak when the scale develops between 59 F and 86 F. In the tropics it breeds year-round with overlapping generations, and three to five generations a year have been recorded in different countries.[1][2]
Damage and signs
- Like other armored scales, it feeds with piercing-sucking mouthparts on individual cells inside leaves, fruit and stems. Heavy infestations cause yellowing and dead tissue, reduced vigor, early leaf drop, poor appearance and declining health.[1]
- Feeding can also discolor and distort leaves and stems, and severe infestations can cause twig dieback and premature fruit drop.[2]
- Water-stressed plants are especially vulnerable, and warm weather boosts populations, a threat to palms and ornamentals in Florida's urban landscapes. It is considered a serious pest of coconut in Florida.[1][2]
Health risk
It is a plant pest; neither source mentions any risk to people or pets.[1][2]
Control
Prevention
Keep plants healthy with proper watering, fertilizing and pruning so they tolerate and recover from infestations. Avoid excess nitrogen, since lush new growth may favor the scale, and choose non-host or less susceptible plants when designing landscapes.[1]
Sanitation
Prune out and destroy heavily infested material, such as infested palm fronds, to cut populations and keep the scale from spreading to nearby plants. Inspect plants with a hand lens for flat, circular, pale-yellow to reddish-brown scales; moving infested plants is how it travels long distances.[1][2]
Biological control
Natural enemies help keep it in check: Chilocorus lady beetles, a predatory mite, green lacewings and many parasitic wasps. In Australia two wasps that also occur in Florida, Encarsia citrina and Aphytis melinus, parasitized up to 80 percent of the scales. Support them with flowering, diverse plantings, shade trees and less pavement around plant bases.[1]
Pesticides
Use insecticides only after pruning and natural enemies have been considered. Spot-treating infested tissue with a mineral oil emulsion works by physical action and is gentler on beneficial insects; selective products such as insect growth regulators and translaminar or systemic products are likely to work best. Avoid broad-spectrum insecticides, and do not use systemic insecticides on plants that attract pollinators.[1]
Biological control has worked elsewhere
In northern Queensland, Australia, where it arrived in 1956 and became the most important pest of papaya, it has been successfully controlled by the parasitic wasps Comperiella lemniscata and Encarsia citrina. Israel imported C. lemniscata and two predatory lady beetles from Australia to fight it on mango.[2]
Diaspididae of the World notes that controlling ants, which improves the work of natural enemies on California red scale, is probably relevant to oriental scale as well.[2]
Common questions
- Is oriental scale found outside Florida in the U.S.?
- UF says it is known to be established only in Florida in the United States, though it can also occur in greenhouses in temperate regions.[1]
- How do I tell it from California red scale?
- Lift the cover: the oriental scale female's yellow body is somewhat swollen but never kidney-shaped, while mature California red scale females are kidney-shaped.[1]
- What is the best way to manage it on palms?
- Combine approaches: keep palms well watered and not overfed with nitrogen, prune and destroy heavily infested fronds, protect lady beetles and parasitic wasps, and if needed spot-treat with a mineral oil emulsion or a selective product.[1]
Sources
- University of Florida IFAS Extension (Featured Creatures), “Oriental Scale, Aonidiella orientalis (Newstead, 1894), EENY-833 (M. V. Solano Gutierrez, E. C. Powell and A. G. Dale, 2026).” journals.flvc.org/edis/article/view/139132 (accessed 2026-11-09)
- Naturalis Biodiversity Center (Diaspididae of the World, with USDA scale insect data), “Diaspididae of the World 2.0: Aonidiella orientalis.” diaspididae.linnaeus.naturalis.nl/linnaeus_ng/app/views/species/taxon.php?id=113045 (accessed 2026-11-09)
- iNaturalist, “Aonidiella orientalis taxon page (order and family).” www.inaturalist.org/taxa/330215 (accessed 2026-11-09)