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FDACS-P-02196
July 2023
PEST ALERT
Pseudaulacaspis coloisuvae Williams and Watson, an armored scale intercepted on orchids
Erin C. Powell; Bureau of Entomology, Nematology and Plant Pathology
DPIHelpline@FDACS.gov or 1-888-397-1517
INTRODUCTION
On June 12, 2023, FDACS-DPI inspectors Grayson Grume and Robert Denoux collected the armored scale, Pseudaulacaspis
coloisuvae Williams and Watson (Hemiptera: Diaspididae), alive on orchids labeled as Vanda sp. (Orchidaceae) imported from
Thailand to a nursery in southwestern Florida. This is the rst time this species has been intercepted in Florida. Pseudaulacaspis
coloisuvae is Australasian in origin, being described from Fiji in 1988 (Williams and Watson 1988) and subsequently reported in the
Solomon Islands in 2011 (Hodgson and Lagowska 2011). It has been intercepted once in the United States by the USDA from the
Philippines and once in Korea from Indonesia (Suh 2016). To date, two hosts have been recorded: Terminalia calamansanai (Blanco)
Rolfe (Combretaceae) and Gardenia sp. (Rubiaceae). Now known on three dierent plant families, this species is likely polyphagous
with a broad host range.
IDENTIFICATION
The elongate oval scale cover, or test, of adult female P. coloisuvae is bright white in color (Fig. 1a–c), while the rst instar nymphs
are light brown and less conspicuous. Like all armored scales, the rst and second instar exuviae (i.e., shed exoskeletons or molts)
are incorporated into the cover as the scale molts to maturity (Fig. 1a–c). Eggs are laid underneath the cover and the mobile
crawlers (rst instars) emerge to disperse. This species is small in size, with the adult female scale cover reaching 2 mm in length
at maturity and the slide-mounted specimens from 0.8–1.2 mm long. Supercially, P. coloisuvae looks similar to the common
congener, Pseudaulacaspis cockerelli (Cooley), colloquially known as the false oleander scale or magnolia white scale. However,
once slide-mounted, microscopic characters easily set these two species apart. Namely, P. coloisuvae has three large dorsal
macroducts on the head, two laterad of the anterior mouthparts, and one set between the antennae. In other Pseudaulacaspis
species, these wax-producing ducts are entirely absent on the head. Other characters of P. coloisuvae include the absence of
submedial dorsal macroducts on abdominal segment VI and zero to one dorsal macroducts on the submedial area of abdominal
segment II.
SURVEY
Armored scales may be present on the leaves, stems or roots of their host plants. In this collection, specimens of P. coloisuvae were
both exposed on the leaf edges and hidden within the nodes of the orchids. Armored scales in the family Diaspididae feed on
intracellular contents and cause chlorosis, or yellowing, usually starting with small irregular patterns around each individual scale.
In heavy infestations, chlorosis can lead to tissue necrosis and leaf death. Plant symptoms may indicate a scale problem before the
scales themselves are noticed. Little is known about the biology or pest potential of this species, but it is probably similar to other
polyphagous armored scales. Specimens may be sent to the Division of Plant Industry for identication. For more information on
how to submit a sample, visit www.FDACS.gov/DPIsamples.
Florida Department of Agriculture and Consumer Services
Division of Plant Industry
123
REFERENCES
Hodgson, C.J. and Lagowska, B. (2011). New scale insect (Hemiptera: Sternorrhyncha: Coccoidea) records from Fiji: three new
species, records of several new invasive species and an updated checklist of Coccoidea. Zootaxa, 2766: 1–29.
Suh, S.J. (2016). Armoured scale insects (Hemiptera: Diaspididae) intercepted at the ports of entry in the Republic of Korea over the
last 20 years. Bulletin OEPP/EPPO Bulletin, 46(2), 313–331.
Williams, D.J. and Watson, G.W. (1988). The Scale Insects of the Tropical South Pacic Region. Pt. 1. The Armoured Scales
(Diaspididae). CAB International Wallingford, U.K., 290 pp.
Fig. 1. Pseudaulacaspis coloisuvae Williams and Watson on the leaves of Vanda orchids. (A) The bright orange body of a live adult female can be seen under
the semi-opaque cover. Note the two overlapping light brown exuviae on the right side are the rst and second instar exuviae incorporated into the adult
female cover. (B) With the cover, or test, removed, the bright orange body of the adult female is exposed. This female had not yet laid eggs. (C) Two adult
females on a leaf.
Photos by Erin C. Powell, FDACS-DPI.
