Family: Scarabaeidae Subfamily: Scarabaeinae Genus: Canthon Species: Canthon pilularius (Linnaeus, 1758)
Total body length 12.0–19.0 mm (0.39–0.59 in). Body shape round (dorsal view); may be caked in dried dung. Color variable; dull, velvety black to dull, bronze or green. Eyes crescent shaped, longer than wide. Clypeus bidentate; surface coarsely granulate. Pronotum and elytra coarsely granulate. Front tibia with apical spur bifurcate in male and spine-like in female (spur may be worn down in older individuals). Middle and hind legs elongate. Pygidium width less than twice the height.
(Ritcher, 1966): Grub C-shaped, hump-backed, cylindrical, whitish. Anal slit transverse. Chaetoparia each with 7–9 setae. Maxillary stridulatory area with 12–17 teeth. Prothoracic shield with anterior projecting, angular process on each side. Legs each with a single long, terminal seta surrounded by 8–9 short setae; 2-segmented; without stridulatory structures; claws absent. Venter of last abdominal segment with single, broad, caudal, median lobe flanked by 2 smaller fleshy lobes; median lobe with 2 inconspicuous patches of very short setae.
Eastern North America. This species is common and widespread across the eastern U.S., occupying much of the area east of the Rocky Mountains and south of the boreal forest (Woodruff, 1973).
Canthon pilularius favors open habitats where it feeds preferentially on horse and cattle dung (Woodruff, 1973). On fresh dung, several hundred individuals may congregate to feed and mate (Ratcliffe and Paulsen, 2008). Dung balls are created and rolled only by the males with females often riding passively atop the balls (Woodruff, 1973). Dung balls may be either eaten by the adults or buried and used for rearing larvae. Dung balls used for larvae each hold a single egg and are buried 7.6–12.7 cm (3.0–5.0 in) deep in firm soils (Ritcher, 1966). In the laboratory, development from egg to adult ranged between 29 and 44 days (Ratcliffe and Paulsen, 2008).
None. This species recycles dung and is beneficial for ranching and farming in Hawaii. Being an obligate dung feeder, this species poses no threat to crop or ornamental plants. Additionally, this species is not a threat to native dung beetles because none are known from Hawaii or Guam.
Established. This species was intentionally released on Oahu in August of 1963 (Hawaiian Entomological Society, 1964). 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). It is established on Oahu (Nishida, 2002).
Not established or recorded. There are no records of this species from Guam.
In Hawaii, this species was intentionally released.
This scarab is one of four Canthon species recorded from Hawaii (none are known from Guam). It is distinguished from the other Canthon species recorded in Hawaii by examination of the pronotal texture (texture coarsely granulate in Canthon pilularius versus smooth in C. viridis, C. indicageus and C. humectus), color (velvety black, bronze or green in Canthon pilularius versus shining green or red in Canthon viridis, dark blue-black in C. humectus), size (12.0–19.0 mm [0.39–0.59 in] in C. pilularius versus 2.0–4.0 mm [0.08–0.16 in] in C. viridis), and shape of the pygidium (pygidium width less than twice the height in Canthon pilularius versus width more than twice the height in C. humectus).
Scarabaeus pilularius Catesby, Scarabaeus laevis Drury, Scarabaeus hudsonias Forster, Scarabaeus volvens Fabricius, Coprobius obtusidens Ziegler, Canthon laevis Horn
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