granulose dung beetle
Family: Scarabaeidae Subfamily: Scarabaeinae Genus: Onthophagus Species: Onthophagus granulatus Boheman, 1858
Total body length 6.0–8.0 mm (0.23–0.31 in). Body shape oval; may be caked in dung. Color dull brownish. Small-sized Onthophagus, 6-10 mm. Clypeal apex of major male produced, strongly recurved; not produced and recurved in minor male or female. Head of male lacking horns; minor male and female with transverse ridge near base. Ocular canthus not completely dividing eye. Pronotum with anterior angle rounded or weakly acute. Pronotum of major male with single lobe-like process; minor male and female with 4 weak, tubercle-like processes. Front tibia of male slender, female tibia comparatively more robust. 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.
Australia. This species is native to eastern Australia. It has been recorded occurring from the province of Victoria northward to Mackay in Queensland (Matthews, 1972). It is also known from New Zealand, where it established in the 1870's (Forgie, 2009).
None. This species feeds on dung as both an adult and larva. There are no records of this beetle feeding on live plant tissues.
This diurnal scarab is known from pastures and other open areas, particularly where soils are sandy (Matthews, 1972). Adults live up to 46 weeks (Forgie, 2009) and have been recorded from carrion as well as dung (human, cattle, sheep, and wallaby) (Matthews, 1972). After locating suitable feces, females create a burrow under or near the dung source (Forgie, 2009). The burrow is then provisioned with dung in the form of brood balls. Each ball is impregnated with an egg; larval development occurs within the brood ball. There is a single generation per year (Forgie, 2009). Duration from egg to adult is 6–10 weeks, with adult numbers peaking in early summer (Forgie, 2009).
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. An odd record of this species killing a horse through perforation of the horse's stomach (Matthews, 1972) should be regarded with skepticism.
Recorded, not established. This species was intentionally brought to Hawaii in 1921, though it is unclear if any individuals were released (Hawaii Division of Forestry, 1923). Similar dung beetle introductions were undertaken to help control populations of the horn fly (Haematobia irritans), a biting pest of livestock (Markin and Yoshioka, 1998). If this species was released, it failed to establish populations in the state (Nishida, 2002).
Not established or recorded. There are no records of this species from Guam.
In Hawaii, this species was intentionally imported.
Major males of these species can quickly be distinguished by examination of the head (O. granulatus lacking horns, instead with strongly recurved, produced clypeal apex versus O. nuchicornis with single spine-like horn, O. foliaceus with a single, long forward curving horn).
Minor males and females are somewhat more difficult to distinguish but can be separated by examination of the pronotum (O. granulatus with four tubercle-like processes versus O. nuchicornis with a rounded peg-like process, O. foliaceus without a process).
Report your observation of this beneficial species at our iNaturalist project.