Ceroplastes rubens Maskell: Red wax scale

California Pest Rating for
Ceroplastes rubens Maskell: Red wax scale
Hemiptera:  Coccidae
Pest Rating:  A

Initiating Event:

February 26, 2014, USDA distributed a Deregulation Evaluation of Established Pests (DEEP) report proposing to change the status of Ceroplastes rubens, red wax scale, from actionable to non-actionable for the entire United States.  The insect is currently A-rated by CDFA, so a pest rating proposal is needed to determine future direction.

History & Status:

BackgroundCeroplastes rubens is a highly polyphagous scale, feeding on hundreds of species of plants in at least 80 families1,5.  It is considered to be a serious pest of citrus2,3,4,5; however, biological control programs have been successful at keeping populations below damaging levels1,3.   In addition to citrus, other economically important hosts in California include avocado, Prunus spp., apple, fig, and an extremely wide variety of ornamentals1,5.  Adults and nymphs feed on foliage, twigs, and stems and are said to have a preference for the upper surface of leaves4.  Red wax scale can move long distances through the international trade of infested plants or plant parts.

Worldwide Distribution: Ceroplastes rubens is so widely distributed that its origin is uncertain.  It is thought to possibly be native to Africa, India, or Sri Lanka2.  From there it has spread widely across much of Asia, Oceania, Australia, and the Caribbean1.  It has also been found in Colombia and greenhouses in Europe1.  The scale has been known from Hawaii since 1894 and Florida since 19551.

Official Control: Ceroplastes rubens is not known to be under official control in any states or nations.

California DistributionCeroplastes rubens has not been found in the environment of California.

California InterceptionsCeroplastes rubens is commonly intercepted by California on shipments of nursery stock from Florida and Hawaii.  The scale is also frequently intercepted by USDA on plants, cuttings, cut flowers, leaves, and fruit1.  Although these interceptions are most common in passenger baggage, they also include finds on large permitted commercial shipments of plants (Aglaonema sp. and Schefflera sp.) from Costa Rica to California1 that would have been likely to contaminate the state’s nursery industry.

The risk Ceroplastes rubens (red wax scale) would pose to California is evaluated below.

Consequences of Introduction: 

1) Climate/Host Interaction: The present distribution of Ceroplastes rubens extends across USDA plant hardiness zones 7-13. This corresponds to most of California, with the exception of high elevation areas.  The polyphagous nature of the scale makes it likely that it will find suitable hosts throughout this area.  Red wax scale receives a High(3) in this category.

Evaluate if the pest would have suitable hosts and climate to establish in California.  Score: 3

Low (1) Not likely to establish in California; or likely to establish in very limited areas.

Medium (2) may be able to establish in a larger but limited part of California.

High (3) likely to establish a widespread distribution in California.

2) Known Pest Host Range: Ceroplastes rubens is known to feed on hundreds of plant species in at least 80 families1,5.  The scale receives a High(3) in this category.

Evaluate the host range of the pest. Score: 3

Low (1) has a very limited host range.

Medium (2) has a moderate host range.

High (3) has a wide host range.

3) Pest Dispersal Potential: Ceroplastes rubens has a high reproductive rate.  In Australia the scale has two generations per year with each female producing an average of about 300 eggs4.  The scales may be spread long distances by wind, as hitchhikers on clothing or animals, or by commerce in infested plants.  Red wax scale receives a High(3) in this category.

Evaluate the natural and artificial dispersal potential of the pest.  Score: 3

Low (1) does not have high reproductive or dispersal potential.

Medium (2) has either high reproductive or dispersal potential.

High (3) has both high reproduction and dispersal potential.

4) Economic Impact:  Ceroplastes rubens may lower crop value and increase production costs in the nursery and fresh fruit industries.  The insects disfigure plants by their presence and their honeydew contributes to the development of sooty mold, which can lower the value of ornamental plants and fruit.  The scale is not known to be listed as a quarantine pest in any nations; however, due to its absence from most of the Americas and New Zealand, it is reasonable to conclude that the scale could interrupt some fresh fruit export markets.  Red wax scale receives a Medium(2) in this category.

Evaluate the economic impact of the pest to California using the criteria below.

Economic Impact: B, C

A. The pest could lower crop yield.

B. The pest could lower crop value (includes increasing crop production costs).

C. The pest could trigger the loss of markets (includes quarantines).

D. The pest could negatively change normal cultural practices.

E. The pest can vector, or is vectored, by another pestiferous organism.

F. The organism is injurious or poisonous to agriculturally important animals.

G. The organism can interfere with the delivery or supply of water for agricultural uses.

Economic Impact Score: 2

Low (1) causes 0 or 1 of these impacts.

Medium (2) causes 2 of these impacts.

High (3) causes 3 or more of these impacts.

5) Environmental Impact: Ceroplastes rubens is likely to trigger new chemical treatments by the nursery industry and by residents who find infested plants unsightly.  Potential hosts of red wax scale include plants listed as threatened or endangered in California including Nevin’s barberry (Berberis nevenii), island barberry (Berberis pinnata insularis), small-leaved rose (Rosa minutifolia), and Algodones Dunes sunflower (Helianthus niveus ssp. tephrodes).  Red wax scale receives a High(3) in this category.

Evaluate the environmental impact of the pest on California using the criteria below.

Environmental Impact: B, D

A. The pest could have a significant environmental impact such as lowering biodiversity, disrupting natural communities, or changing ecosystem processes.

B. The pest could directly affect threatened or endangered species.

C. The pest could impact threatened or endangered species by disrupting critical habitats.

D. The pest could trigger additional official or private treatment programs.

E. The pest significantly impacts cultural practices, home/urban gardening or ornamental plantings.

Score the pest for Environmental Impact.

Environmental Impact Score: 3

Low (1) causes none of the above to occur.

Medium (2) causes one of the above to occur.

High (3) causes two or more of the above to occur.

Consequences of Introduction to California for Ceroplastes rubens (red wax scale):  High(14)

Add up the total score and include it here.

Low = 5-8 points

Medium = 9-12 points

High = 13-15 points

6) Post Entry Distribution and Survey Information: Ceroplastes rubens has not been found in the environment of California and receives a Not established(0) in this category.

Evaluate the known distribution in California. Only official records identified by a taxonomic expert and supported by voucher specimens deposited in natural history collections should be considered. Pest incursions that have been eradicated, are under eradication, or have been delimited with no further detections should not be included.

Not established (0) Pest never detected in California, or known only from incursions.

Low (-1) Pest has a localized distribution in California, or is established in one suitable climate/host area (region).

Medium (-2) Pest is widespread in California but not fully established in the endangered area, or pest established in two contiguous suitable climate/host areas.

High (-3) Pest has fully established in the endangered area, or pest is reported in more than two contiguous or non-contiguous suitable climate/host areas.

Final Score:

The final score is the consequences of introduction score minus the post entry distribution and survey information score: High(14)


It is possible that Ceroplastes rubens would be managed by existing IPM programs in California fruit production.  It is also possible that existing packing house procedures would mitigate potential trade disruptions.

Conclusion and Rating Justification:

Ceroplastes rubens (red wax scale) is a highly polyphagous scale insect that is likely to have significant economic and environmental impacts in California.  The scale is likely to contaminate fresh fruit (Citrus and Prunus spp.) with its presence and sooty mold, reducing fruit marketability and possibly disrupting export markets.  The scale is also likely to increase production costs in the nursery industry as it feeds on an extremely wide variety of ornamental plants.  Red wax scale is likely to trigger new chemical treatments in the nursery and fruit industries, as well as by residents who find infested plants unsightly.  At least four threatened or endangered plants are potential hosts of the scale in California and are likely to be directly affected by feeding.  These potential economic and environmental impacts justify an A-rating for Ceroplastes rubens.


1Culliney, T.W.  2014.  Deregulation Evaluation of Established Pests (DEEP); DEEP Report on Ceroplastes rubens Maskell: Red wax scale.

2Loch, A.D. 1997.  Natural enemies of pink wax scale, Ceroplastes rubens Maskell (Hemiptera: Coccidae), on umbrella trees in southeastern Queensland.  Australian Journal of Entomology 36:303-306.  http://onlinelibrary.wiley.com/doi/10.1111/j.1440-6055.1997.tb01475.x/pdf

3UC Riverside, Red wax scale.  http://www.faculty.ucr.edu/~legneref/biotact/ch-92.htm

4Malumphy, C. and D. Eyre.  2011.  Pink wax scale: Ceroplastes rubens.  Plant pest factsheet.  The Food and Environment Research Agency (Fera). U.K.  http://www.fera.defra.gov.uk/plants/publications/documents/factsheets/ceroplastesRubens.pdf

5Dekle, G.W.  2001.  Featured Creatures: Red wax scale: Ceroplastes rubens.  Florida Dept. of Agriculture and Consumer Services, Division of Plant Industry.  http://entnemdept.ufl.edu/creatures/orn/scales/red_wax_scale.htm

Responsible Party:

Jason Leathers, 1220 N Street, Sacramento, CA, 95814, (916) 654-1211, plant.health[@]cdfa.ca.gov.

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Pest Rating:  A

Posted by ls