Anomala orientalis

Pest

Common name(s)

oriental beetle

Taxonomy

Family: Scarabaeidae Subfamily: Rutelinae Genus: Anomala Species: Anomala orientalis (Waterhouse, 1875)

Adult diagnosis

Total body length 8.0–13.0 mm (0.31–0.51 in). Body shape ovate; female often wider than male. Color tan to black; tan specimens often with black markings of variable size and position. Front tibia with two external teeth; apical tooth long and decurved, longer in female than male; basal tooth evident in male and female. Front claw bifurcate; bifurcate claw never sinuate; female claws less robust than in male. Hind tibia with inner margin simple, not greatly dilated at the middle.

Larval diagnosis

(Ritcher, 1966): Grub C-shaped, not hump-backed, cylindrical, whitish. Maxilla with galea and lacinia entirely fused. Lacinia of maxilla with 2 unci. Maxillary teeth anteriorly projecting. Dorsoexterior region of mandible bare. Crest of labrum not strongly rugose. Haptomerum of epipharynx with a transverse row of 3 prominent unci; never with a conspicuous, transverse, curved row of stout setae. Last antennal segment with a single sensory spot. Posterior frontal setae consisting of 2 single setae. Dorsa of abdominal segments 7–9 rather uniformly covered with many medium-sized setae; each bearing a caudal transverse row of 5 or 6 very long setae. Septula oblong; palidia monostichous, slightly diverging, each set with 11–15 pali. Anal slit slightly curved, transverse.

Native range

Uncertain. This species is probably native to either Japan or the Philippines (Reding and Klein, 2006). Because Anomala orientalis is an established, non-native pest in Korea (Choo et al., 2002) and the U.S. (Maine west to Ohio and south to the Carolinas) (CABI, 2015), an origin in temperate Japan may be more likely, though this remains speculation.

Plant host(s)

This scarab feeds on plants as both larva and adult. Adults are minor pests, sometimes causing damage to horticultural species such as Dahlia spp., hollyhock (Alcea spp.), Iris spp., Petunia spp., Phlox spp., and roses (Rosa hybrida). Larvae are more serious pests, feeding on the roots of important crop and turf species including: corn (Zea mays), cranberry (Vaccinium spp.), creeping bentgrass (Agrostis stolonifera), Japanese chestnut (Castanea crenata), manila grass (Zoysia matrella), nandina (Nandina domestica), perennial ryegrass (Lolium perenne), pineapple (Ananas comosus), raspberry (Rubus spp.), reed fescue (Festuca arundinacea), smooth-stalked meadowgrass (Poa pratensis), strawberry (Fragaria × ananassa), and sugarcane (Saccharum officinarum).

Life history

(CABI, 2015): In New York, this species has a one year lifecycle. Adults emerge in late June and remain active until August. Adults are weak fliers and are active at night. Females deposit eggs in damp soil, with larvae emerging from the eggs after 17–25 days. First instars are encountered by August, second instars by September, and final instars begin appearing by early October. Overwintering occurs in the final instar. Feeding on plant roots, which occurs close to the surface, resumes in late March or early April.

Pest potential

Significant. This species is a known biosecurity threat, having a long history biological invasion. In California, Anomala orientalis is officially a species of biosecurity concern and is regarded as having a moderate risk of introduction (Cosner, 2013). Larvae are major turf pests and also attack a range of crop plants. In Hawaii, this species historically has been a major pest of sugarcane and pineapple (Pemberton, 1964.).

Status in Hawaii

Established. Anomala orientalis is known from Oahu, where it became established sometime before 1908 (Myers et al., 2003). Interestingly while this species was once a common pest (Pemberton, 1964) on the island, anecdotal evidence suggest its numbers on Oahu have declined significantly over the last several decades.

Status in Guam

Not established or recorded. There are no records of this species from Guam.

Potential distribution and dispersal pathway

Anomala orientalis has a long history as an invasive species, having become established in Hawaii before 1908 and Connecticut (and hence the rest of the northeastern U.S.) by 1920 (Alm, 1996). The species should be treated as having some potential of establishing on the other islands. While the means of its arrival in Hawaii are uncertain, it was noted that the Connecticut population appears to have arrived in balled nursery stock from Japan (Alm, 1996). Because adults feed on many plants of horticultural importance and are easily overlooked, hitchhiking on transported garden plants likely represents a major mode of invasion. Grass sod carrying larvae could also represent a potential pathway; adults attracted to lights at major shipping points such as ports and airports and subsequently stowing away on cargo could represent another.

Similar species

Anomala orientalis is one of five Anomala species known from Hawaii and Guam, along with Anomala cuprea, Anomala sulcatula, Anomala viridana, and Anomala albopilosa. It can be separated from the other species based upon by examination of the bifurcate male front claw (curved but non-sinuate in A. orientalis versus strongly sinuate in A. cuprea and A. viridana, weakly sinuate in A. albopilosa), the hind tibia of males (A. orientalis not greatly dilated at the middle on the inner margin versus inner margin greatly dilated at the middle in A. sulcatula), and body size (A. orientalis at 8.0–13.0 mm [0.31–0.51 in] versus 14.0 mm [0.55 in] or greater in the other recorded Anomala species).

Other names (synonyms)

Blitopertha orientalis (Waterhouse), Exomala flavipennis Reitter, Exomala orientalis (Waterhouse), Exomala tanbaensis Niijima and Kinoshita, Exomala xanthrogasta Harold, Phyllopertha orientalis Waterhouse

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Anomala orientalis female. By EL Engasser

Anomala orientalis female. By EL Engasser

Anomala orientalis female. By EL Engasser

Anomala orientalis female. By EL Engasser

Anomala orientalis color morph. By EL Engasser

Anomala orientalis color morph. By EL Engasser

Anomala orientalis color morph. By EL Engasser

Anomala orientalis color morph. By EL Engasser

Anomala orientalis color morph. By EL Engasser

Anomala orientalis color morph. By EL Engasser

Anomala orientalis color morph. By EL Engasser

Anomala orientalis color morph. By EL Engasser

Anomala orientalis male foretibia. By EL Engasser

Anomala orientalis male foretibia. By EL Engasser

Anomala orientalis male foreclaw. By EL Engasser

Anomala orientalis male foreclaw. By EL Engasser

Anomala orientalis female foretibia. By EL Engasser

Anomala orientalis female foretibia. By EL Engasser

Anomala orientalis male genitalia, dorsal view. By EL Engasser

Anomala orientalis male genitalia, dorsal view. By EL Engasser

Anomala orientalis male genitalia, lateral view. By EL Engasser

Anomala orientalis male genitalia, lateral view. By EL Engasser

distribution map for Anomala orientalis

distribution map for Anomala orientalis