coastal dung beetle, black-bottom dung beetle
Family: Scarabaeidae Subfamily: Scarabaeinae Genus: Onthophagus Species: Onthophagus nigriventris D'Orbigny, 1902
Total body length 10.0–17.0 mm (0.39–0.67 in). Body shape oval; may be caked in dung. Color black with greenish cast; elytra brown. Medium-sized Onthophagus, more than 10 mm. Clypeal apex not strongly produced or reflexed in either sex. Major male lacking horns, tubercles, or ridges on head; head of minor male and female with sinuate ridge near base. Ocular canthus not completely dividing eye. Pronotum of major male produced into long, straight horn with smaller bi-lobed process above horn; minor male and female with lobe-like process. Pronotum with anterior angles rounded. Front tibia of males somewhat slender and elongate; female tibia comparatively stout. Scutellum absent.
Undescribed. 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.
East Africa. This species is native to moist highlands in eastern Africa. It also was introduced to Australia (Tyndale-Biscoe, 1990).
None. This species feeds on dung as both an adult and larva. There are no records of this beetle feeding on live plant tissues.
(Tyndale-Biscoe, 1990): Adults of this diurnal species live 2–4 months. During that time, adults actively fly in search of fresh dung. Females create oval-shaped brood balls in burrows constructed under or near dung. Development from egg to adult requires 4–7 weeks. There are multiple generations per year.
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 species is not a threat to native dung beetles because none occur in Hawaii or Guam.
Established. In Hawaii, this species was imported in 1975 to Big Island and Maui to combat the horn fly (Haematobia irritans), a biting pest of livestock (Markin and Yoshioka, 1998). It is established in the highlands of both islands, being rare on Maui (Krushelnycky et al., 2007) but more common on Big Island (Markin and Yoshioka, 1998).
Not established or recorded. There are no records of this species from Guam.
In Hawaii, this species was intentionally imported.
This species could be confused with the similarly colored and medum-sized (more than 10 mm) Digitonthophagus gazella and Onthophagus sagittarius.
Major males are readily separated by examining the head armature (O. nigriventris lacking horns on head versus D. gazella with 2 short, upward curving horns and O. sagittarius with 2 tusk-like horns).
Minor males and females can be separated by examining base of the head (O. nigriventris with a sinuate ridge versus D. gazella with straight, transverse ridge versus O. sagittarius with single horn).
none known
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