Onthophagus nuchicornis

Beneficial

Common name(s)

small black and brown dung beetle

Taxonomy

Family: Scarabaeidae Subfamily: Scarabaeinae Genus: Onthophagus Species: Onthophagus nuchicornis (Linnaeus, 1758)

DNA barcode

DNA barcode available: specimen information

Adult diagnosis

Total body length 6.7–9.5 mm (0.26–0.37 in). Body shape oval; may be caked in dung. Color black; elytra brown, mottled with black. Small-sized dung beetle, 6-10 mm. Clypeal apex weakly sinuate; not strongly produced or reflexed in either sex. Head of major male with single spine-like horn; minor male horn greatly reduced; female with transverse ridge at base of head. Ocular canthus completely dividing eye. Pronotum with anterior angles rounded. Pronotum of major male with slight hump-like process; process reduced in minor male; female with rounded peg-like process. Front tibia of male somewhat slender, female tibia comparatively more stout. Scutellum absent.

Larval diagnosis

Undescribed in English (see Perris, 1877): For Onthophagus spp. (Ritcher, 1966): Grub C-shaped, hump-backed, cylindrical, and cream-colored. Maxilla with galea and lacinia distinctly separate. Epipharynx with tormae united mesally, anterior phoba present. Antennae 4-segmented, distal segment much reduced. Legs 2-segmented. Prothoracic shield without anteriorly projecting processes. Third abdominal segment bearing a prominent conical, dorsal gibbosity covered with numerous short, stout setae.

Native range

Temperate Eurasia. This species is native to a broad area of temperate Eurasia, occurring from Europe and Turkey eastward to Siberia and Mongolia (Global Biodiversity Information Facility, 2015). This species was also introduced to North America in the 1840's and occurs coast to coast, from southern Canada south to Missouri (MacRae and Penn, 2001).

Plant host(s)

None. This species feeds on dung as both an adult and larva. There are no records of this beetle feeding on live plant tissues.

Life history

Adults of this species have been recorded on cattle and horse dung (Howden and Cartwright, 1963). Like many related Onthophagus species, O. nuchicornis is a dung tunneler (MacQueen and Beirne, 1975), creating a burrow near or under a fecal source. The burrow is then provisioned with feces in the form of brood balls. An egg is deposited in each brood ball, within which larval development occurs.

Pest potential

None. This species recycles dung and is beneficial for ranching and farming in Hawaii. Primarily being a dung feeder, this species has never been recorded damaging crop or ornamental plants. Additionally, this scarab is not a threat to native dung beetles because none occur in Hawaii or Guam.

Status in Hawaii

Recorded, not established. In Hawaii, this species was imported in 1910 to combat the horn fly (Haematobia irritans), a biting pest of livestock. However, imported specimens did not thrive and none were released (Division of Forestry, 1910).

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 was intentionally imported.

Similar species

This species could be confused with Onthophagus of similar small size (6–10 mm) and color: Onthophagus foliaceus and Onthophagus granulatus.

Males of these species can quickly be distinguished by examining the head armature (O. nuchicornis with single spine-like horn versus O. foliaceus with a single, long, forward curving horn; O. granulatus lacking horn, but with an almost vertically produced clypeal apex).

Females are somewhat more difficult to distinguish, but they can be separated by examining the pronotum (O. nuchicornis with rounded peg-like process versus O. foliaceus without process, and O. granulatus with four tubercle-like processes).

Other names (synonyms)

Onthophagus acornis Geoffrey in Fourcoy, Onthophagus alpinus Kolenati, Onthophagus dilwyni Stephens Onthophagus immaculatus Mulsant, Onthophagus indistinctus Mulsant, Onthophagus planicornis Herbst in Fuessly, Onthophagus rhinoceros Melsheimer, Onthophagus rubripes Mulsant, Onthophagus submarginalis Sahlberg, Onthophagus trituberculatus Schrank, Onthophagus vulneratus Mulsant, Onthophagus xiphias Fabricius

Report your observation

Report your observation of this beneficial species at our iNaturalist project.

Onthophagus nuchicornis male; photo by E.L. Engasser

Onthophagus nuchicornis male; photo by E.L. Engasser

Onthophagus nuchicornis male; photo by E.L. Engasser

Onthophagus nuchicornis male; photo by E.L. Engasser

Onthophagus nuchicornis male; photo by E.L. Engasser

Onthophagus nuchicornis male; photo by E.L. Engasser

Onthophagus nuchicornis male; photo by E.L. Engasser

Onthophagus nuchicornis male; photo by E.L. Engasser

Onthophagus nuchicornis female; photo by E.L. Engasser

Onthophagus nuchicornis female; photo by E.L. Engasser

Onthophagus nuchicornis female; photo by E.L. Engasser

Onthophagus nuchicornis female; photo by E.L. Engasser

Onthophagus nuchicornis male genitalia, lateral view; photo by E.L. Engasser

Onthophagus nuchicornis male genitalia, lateral view; photo by E.L. Engasser