Protaetia orientalis

Pest

Common name(s)

oriental flower beetle, Asian flower beetle

Taxonomy

Family: Scarabaeidae Subfamily: Cetoniinae Genus: Protaetia Species: Protaetia orientalis (Gory and Percheron, 1833)

Adult diagnosis

Total body length 19.9–26.8 mm (0.78–1.1 in). Body broadly oval; dorsoventrally flattened. Color shiny black, rarely shiny greenish; elytra with prominent to indistinct pale markings. Clypeus broad, anterior margin entire to sinuate. Front tibia of male with 2 or 3 external teeth (third tooth weak); female with 3 external teeth. Hind tibia with 2 lateral ridges. Elytra lacking apical spine in both sexes.

Larval diagnosis

Undescribed in English. For Cetoniinae (Ritcher, 1966): Like other Protaetia species, when alive, larvae crawl on their backs with their legs up, and they feel distinctly "squishy" rather than firm (a characteristic of coconut rhinoceros beetle [Oryctes rhinoceros] larvae). Grub C-shaped, not hump-backed, cylindrical, whitish. Maxilla with galea and lacinia fused, or nearly so. Labrum symmetrical. Claws of hind leg large, cylindrical, and hairy. Abdominal segments 9 and 10 fused. Anal opening transverse, straight to slightly curved.

Native range

East Asia. Protaetia orientalis is a native of East Asia (LeBlanc et al., 2013), ranging from China to Korea and Japan (Marler and Muniappan, 2006).

Plant host(s)

Adults of this species are generalist frugivores and are associated with the flowers and overripe or damaged fruit of 42 recorded plant species in 25 families (Ijima and Takeuchi, 2007). Commercially important among these are papaya (Carica papaya), coconut (Cocos nucifera), mango (Mangifera indica), banana (Musa spp.), sorghum (Sorghum bicolor), and corn (Zea mays). Additionally, the Asian flower beetle is known to opportunistically feed from sap flows (Ijima and Takeuchi, 2007). In Guam, this species is a minor pest of the endangered Micronesian cycad (Cycas micronesica) (Marler and Muniappan, 2006). Larvae are not plant pests and subsist on organic soil debris and compost (Kim et al., 2002), as is typical of many cetoniine scarab larvae (Ritcher, 1966).

Life history

(Kim et al., 2002): In Korea, adults are active from April until October, with peak abundance occurring in July and August. Larvae overwinter in the final instar, with pupation occurring in the following spring. The first larval instar lasts an average of 10.6 days, the second instar 18.7 days, the final instar 38.1 days, and pupation averaged 35.5 days. Female adults live an average of 135.2 days, during which an average of 82.8 eggs were laid. Larvae feed on organic soil debris. Adults of this species are diurnal and may be found feeding or actively flying at midday, particularly on warm, sunny days. It is not clear that Hawaiian or Guamanian populations of the Asian flower beetle show the same strong seasonal patterns that are observed in Korea. In Guam, museum specimens provide evidence that adults are found throughout the year.

Pest potential

Moderate. Like the Midway emerald beetle (Protaetia pryeri), this species can often be found in large feeding aggregations on fruit. While the sight of these aggregations may be alarming for plant owners, they rarely cause significant damage to healthy fruit; instead, beetles prefer overripe or already damaged fruits, perhaps attracted to the odors of fermentation (LeBlanc et al., 2013). Beetles are, however, capable of causing a degree of mechanical damage to surrounding healthy fruits or flowers with their sharp tarsal claws when they clamber towards fruit (LeBlanc et al., 2013).

Status in Hawaii

Established. The first record of this species dates to 1952, when a live specimen was found on an aircraft flying into Hickam Air Force Base from Japan (Hawaiian Entomological Society, 1952A). USDA APHIS records show further quarantine interceptions from Air Force aircraft arriving from Andersen Air Force Base in Guam in the 1980's and 90's (Moore, 2012). However, populations did not become established on Oahu until 2002. The species reached Maui in 2010 and Big Island in 2013 (LeBlanc et al., 2013).

Status in Guam

Established. This species has been present in Guam since the 1970's (LeBlanc et al., 2013) and is now one of the more common and visible scarabs on the island.

Potential distribution and dispersal pathway

Adults of this species have an established history of hitchhiking aboard military aircraft (Moore, 2012). As such, United States Air Force bases in California and Florida should be regarded as very likely sites of future introductions. Indeed, in California this species was intercepted in quarantine at San Mateo in 2003 (Gaimari, 2005) and is now regarded as a class A pest species (Cosner, 2013). Further, because adults are attracted to fermenting fruits and nectar-bearing flowers, it is possible that the Protaetia orientalis could hitchhike on nursery plants. Adults could also be accidentally spread in shipments of commercially grown fruits.

Similar species

This beetle is one of the three species in the genus Protaetia known from Hawaii and Guam. The remaining two species are Protaetia pryeri and Protaetia fusca. These three species are separated by size (P. orientalis at 19.9–26.8 mm [0.78–1.1 in] versus P. fusca at 12.0–17.0 mm [0.47–0.67 in]), examination of the elytral apices (P. orientalis and P. pryeri always without apical spines versus P. fusca with apical spines in the male), and hind tibia (P. orientalis with 2 lateral ridges versus P. fusca and P. pryeri with a single lateral ridge).

Other names (synonyms)

Cetonia orientalis Gory and Percheron, Calopotosia orientalis (Gory and Percheron), Protaetia aereta Erichson, Protaetia speculifera Schauman

Report your observation

Report your observation of this species at our iNaturalist project.

Protaetia orientalis male; photo by E.L. Engasser

Protaetia orientalis male; photo by E.L. Engasser

Protaetia orientalis male; photo by E.L. Engasser

Protaetia orientalis male; photo by E.L. Engasser

Protaetia orientalis female, color morph; photo by E.L. Engasser

Protaetia orientalis female, color morph; photo by E.L. Engasser

Protaetia orientalis male hind leg, ventral view; photo by E.L. Engasser

Protaetia orientalis male hind leg, ventral view; photo by E.L. Engasser

Protaetia orientalis male foretibia; photo by E.L. Engasser

Protaetia orientalis male foretibia; photo by E.L. Engasser

Protaetia orientalis female foretibia; photo by E.L. Engasser

Protaetia orientalis female foretibia; photo by E.L. Engasser

Protaetia orientalis male genitalia, caudal view; photo by E.L. Engasser

Protaetia orientalis male genitalia, caudal view; photo by E.L. Engasser

Protaetia orientalis male genitalia, lateral view; photo by E.L. Engasser

Protaetia orientalis male genitalia, lateral view; photo by E.L. Engasser

Protaetia orientalis larval frass; photo by M.L. Jameson

Protaetia orientalis larval frass; photo by M.L. Jameson

Protaetia orientalis feeding on papaya; photo by E.L. Engasser

Protaetia orientalis feeding on papaya; photo by E.L. Engasser

Protaetia orientalis (Asian flower beetle) larva in comparison to Oryctes rhinoceros (coconut rhinoceros beetle); photo by M.L. Jameson

Protaetia orientalis (Asian flower beetle) larva in comparison to Oryctes rhinoceros (coconut rhinoceros beetle); photo by M.L. Jameson

distribution map for Protaetia orientalis

distribution map for Protaetia orientalis