Family: Scarabaeidae Subfamily: Scarabaeinae Genus: Canthon Species: Canthon humectus (Say, 1831)
Total body length 10.0–17.0 mm (0.39–0.67 in). Body shape round (dorsal view); may be caked in dried dung. Color dark blue-black; weakly metallic. Eyes crescent shaped; longer than wide. Clypeus bidentate; surface smooth, never coarsely granulate. Pronotum and elytra smooth, never 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 more than twice height.
Undescribed. For Canthon spp. (Ritcher, 1966): Grub C-shaped,hump-backed, cylindrical, whitish. Prothoracic shield with anterior projecting, angular process on each side. Legs each with a single long, terminal seta surrounded by numerous short setae; 2-segmented; without stridulatory structures; claws absent. Anal slit transverse.
Central Mexico to Guatemala. This species is known primarily from the high plateau of central Mexico, though it has been recorded south to the highlands of Guatemala (Halffter et al., 2011) and north to the Mexican state of Sonora (Navarrete-Heredia, 2012).
None. This species feeds on dung as both an adult and larva (Ortega-Martínez et al., 2014).
Similar to other Canthon spp., this diurnal scarab is a dung roller (Ortega-Martínez et al., 2014). It is known primarily from elevations between 1,200–2,000 meters (3,900–6,500 ft) where it occurs in pastures, shrubland, and rarely in open forests (Halffter et al., 2011). In central Mexico, it is amongst the most common dung beetle species found in cattle pastures and shows a strong affinity for cattle droppings (Ortega-Martínez et al., 2014). Males arrive at droppings and shape a portion of dung into a ball. The dung ball is then rolled, or "tumbled", away from the initial dung source. Females do not roll dung but may passively ride atop the ball. Adults may consume the dung ball, or a single egg may be deposited in it and then buried in the soil by the male for larval consumption (Ortega-Martínez et al., 2014).
None. This species recycles dung and is beneficial for ranching and farming in Hawaii. Being a 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 occur in Hawaii or Guam.
Established. This species was intentionally introduced to Big Island twice (once in 1923 and again in 1952) to help control populations of the horn fly (Haematobia irritans), a biting pest of livestock (Markin and Yoshioka, 1998). It is also known from Maui (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 smooth in Canthon humectus versus coarsely granulate in C. pilularius), color (dark blue-black in C. humectus, versus dark metallic green in C. indigaceus, velvety black to green in C. pilularius, shining green or red in C. viridis), size (10.0–17.0 mm [0.39–0.67 in] in C. humectus versus 2.0–4.0 mm [0.08–0.16 in] in C. viridis), and pygidium shape (pygidium width more than twice the height in C. humectus versus width less than twice the height in C. viridis, C. pilularius and C. indigaceus).
Canthon amythestinus Harold, Canthon gagatinus Harold
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