Trox scaber

Status

Beneficial

Common name(s)

hide beetle

Taxonomy

Family: Trogidae Subfamily: Troginae Genus: Trox Species: Trox scaber (Linnaeus, 1767)

DNA barcode

DNA barcode available: specimen information; sequence data

Adult diagnosis

Total body length 5.0–7.0 mm (0.19–0.28 in). Body shape oval (dorsal view), surface rough and warty, often dirt encrusted. Venter flat, dorsum convex (lateral view). Color dark grey-brown. Pronotumpronotum:
the dorsal surface of the thorax
with base weakly sinuatesinuate:
gently curved (specifically of margins or edges); often in reference to the clypeus
, basal anglebasal angle:
in reference to the pronotum, the basal and lateral corner
quadrate. Scutellumscutellum:
the triangular portion of the thorax between the bases of the elytra
rounded, never hastatehastate:
somewhat diamond-like in shape
. ElytraElytra:
the hardened and chitinous wing-cover of a beetle that protect and overlie the flight wing
with patches of short, reddish-brown hairs. Middle tibiatibia:
a segment of the leg articulated with the tarsus and femur
lacking numerous fine teeth along outer margin.

Larval diagnosis

Undescribed. For Trox (Ritcher, 1966Ritcher, 1966:
Ritcher P. 1966. White grubs and their allies: a study of North American scarabaeoid larvae. Oregon State University Monographs, Studies in Entomology 4: 1-219.): Grub C-shaped, not hump-backed, cylindrical, whitish. Maxillamaxilla:
set of paired mouthparts located posterior to the mandibles
with galeagalea:
outer branch or lobe of the maxilla
and lacinialacinia:
inner portion of the maxilla
distinctly separated. AntennaeAntennae:
paired sensory organ on head, formed from numerous segments
with 3 segments, with distaldistal:
situated away from the point of articulation, thus usually furthest from the body
sensory cone on second segment. Distaldistal:
situated away from the point of articulation, thus usually furthest from the body
segment of antennaeantennae:
paired sensory organ on head, formed from numerous segments
much reduced in size. Epipharynxepipharynx:
lobe on the interior surface of the labrum or clypeus
with tormaetormae:
in scarab larvae, sclerotized structures on the ends of the clypeolateral suture extending towards the mesal line
united mesallymesally:
at or near midline of body
. Legs 4-segmented, never with stridulatory organ. Spiraclesspiracles:
opening on the abdomen or thorax through which air enters and exits the body
of thorax and abdomen biforousbiforous:
possessed of two pores or perforations
.

Native range

Holarctic, Australia, southern South America. Trox scaber is widely distributed across the temperate Northern and Southern Hemispheres (Zidek, 2013Zidek, 2013:
Zidek J. 2013. Checklist and bibliography of the Trogidae (Coleoptera: Scarabaeoidea). Insecta Mundi 314: 1-38. full text (accessed 2015)). It is widely distributed in the Palearctic, from the Canary Islands and North Africa eastward to Siberia. In North America, this species occurs from southern Canada through the northern half of the contiguous U.S. (Ratcliffe and Paulsen, 2008Ratcliffe and Paulsen, 2008:
Ratcliffe B and Paulsen P. 2008. The scarabaeoid beetles of Nebraska (Coleoptera: Scarabaeoidea). Bulletin of the University of Nebraska 22: 138-248.). In the Southern Hemisphere, the species is known from Australia and Argentina, and recorded (but not thought established) in Chile (Zidek, 2013Zidek, 2013:
Zidek J. 2013. Checklist and bibliography of the Trogidae (Coleoptera: Scarabaeoidea). Insecta Mundi 314: 1-38. full text (accessed 2015)).

Plant host(s)

None. Both adults and larvaelarvae:
the immature form of an insect; in scarabs, also called grub or white grub; preceded by the egg stage, followed by the pupal stage
of this species feed on late stage carrion and other dry animal remains, thus posing no threat to crops or ornamental plants.

Life history

Both adults and larvaelarvae:
the immature form of an insect; in scarabs, also called grub or white grub; preceded by the egg stage, followed by the pupal stage
of this species feed on feathers, hair, and other dry animal remains. These remains may consist of debris in mammal burrows, bird nest debris, dry carrion, or regurgitated owl pellets (Ratcliffe and Paulsen, 2008Ratcliffe and Paulsen, 2008:
Ratcliffe B and Paulsen P. 2008. The scarabaeoid beetles of Nebraska (Coleoptera: Scarabaeoidea). Bulletin of the University of Nebraska 22: 138-248.). Females lay eggs in batches of 3 or 4, burying them 1–3 mm (0.4–1.2 in) beneath an animal carcass. LarvaeLarvae:
the immature form of an insect; in scarabs, also called grub or white grub; preceded by the egg stage, followed by the pupal stage
emerge from eggs after 8 or 9 days and begin feeding. Pupation occurs in a cell beneath the feeding site. It appears that only a single generation is produced per year, with overwintering occurring in the adult stage (Baker, 1966Baker, 1966:
Baker C. 1966. Larval systematics of the Troginae in North America with notes on biologies and life histories (Coleoptera: Scarabaeidea). PhD dissertation, Oregon State University. full text (accessed 2015)), though it is unclear that this is true of Hawaiian populations. In Nebraska, adults of this species have been found from April through September (Ratcliffe and Paulsen, 2008Ratcliffe and Paulsen, 2008:
Ratcliffe B and Paulsen P. 2008. The scarabaeoid beetles of Nebraska (Coleoptera: Scarabaeoidea). Bulletin of the University of Nebraska 22: 138-248.). This species is known to be attracted to lights at night (Hawaiian Entomological Society, 1977Hawaiian Entomological Society, 1977:
Anonymous. 1977 . Trox spp . in Hawaii. Proceedings of the Hawaiian Entomological Society 22: 397-398. full text (accessed 2015)) and is likely nocturnal.

Pest potential

None. This species recycles carrion and poses no threat to crop or ornamental plants.

Status in Hawaii

Established. Trox scaber first arrived to Hawaii around 1900, first being recorded near Hilo on Big Island. To date, this species appears confined to Big Island, with most specimens found at lights (Hawaiian Entomological Society, 1977Hawaiian Entomological Society, 1977:
Anonymous. 1977 . Trox spp . in Hawaii. Proceedings of the Hawaiian Entomological Society 22: 397-398. full text (accessed 2015); Nishida, 2002Nishida, 2002:
Nishida G (editor). 2002. Hawaiian terrestrial arthropod checklist, fourth edition. Bishop Museum Technical Report 22: 1-313.).

Status in Guam

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

Potential distribution and dispersal pathway

In Hawaii, this species may have first arrived in marine cargo, though this is speculation This species is native to the U.S. (Ratcliffe and Paulsen, 2008Ratcliffe and Paulsen, 2008:
Ratcliffe B and Paulsen P. 2008. The scarabaeoid beetles of Nebraska (Coleoptera: Scarabaeoidea). Bulletin of the University of Nebraska 22: 138-248.), thus it does not pose a threat in the contiguous U.S.

Similar species

Trox scaber is one of three hide beetles (Trogidae) known from Hawaii and Guam. The other two species are Omorgus procerus and O. suberosus. These species are separated by size (T. scaber at 5.0–7.0 mm [0.19–0.28 in] versus O. suberosusand O. procerusboth over 10.0 mm [0.39 in]) and by examining the pronotumpronotum:
the dorsal surface of the thorax
(T. scaber with the pronotal base weakly sinuatesinuate:
gently curved (specifically of margins or edges); often in reference to the clypeus
and basal anglebasal angle:
in reference to the pronotum, the basal and lateral corner
quadrate versus O. suberosusand O. proceruswith pronotal base scalloped and the basal anglebasal angle:
in reference to the pronotum, the basal and lateral corner
obtuse), scutellumscutellum:
the triangular portion of the thorax between the bases of the elytra
(T. scaber with scutellumscutellum:
the triangular portion of the thorax between the bases of the elytra
rounded versus O. suberosusand O. procerusboth with scutellumscutellum:
the triangular portion of the thorax between the bases of the elytra
hastatehastate:
somewhat diamond-like in shape
), and middle tibiatibia:
a segment of the leg articulated with the tarsus and femur
(T. scaber without middle tibiatibia:
a segment of the leg articulated with the tarsus and femur
lacking numerous fine teeth along lateral margin versus O. proceruswith numerous, fine teeth).

Other names (synonyms)

Silpha scabra Linnaeus, Trox barbosus von Laicharting, Trox arenarius Fabricius, Trox hispidus von Paykull, Trox trisulcatus Curtis, Trox niponensis Lewis

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