Phanaeus daphnis

Beneficial

Common name(s)

none known

Taxonomy

Family: Scarabaeidae Subfamily: Scarabaeinae Genus: Phanaeus Species: Phanaeus daphnis Harold, 1863

Adult diagnosis

Total body length 13.0–19.0 mm (0.51–0.74 in). Color metallic green, rarely blue or yellow-green. Head of major male with single large horn; horn reduced in minor males, lacking in female. Clypeus usually rounded, sometimes triangular or trapezoidal; never strongly emarginated. Pronotum of major male with 3 elevated ridges; ridges reduced in minor males, absent in females. Pronotal surface at lateral margins granulate. Elytra with distinct striae. Middle and hind legs without claws.

Larval diagnosis

Undescribed. For Phanaeus species (Ritcher, 1966): Maxilla with galea and lacinia distinctly separated. Epipharynx with tormae united mesally, anterior phoba present. Antenna 4- segmented; distal segment of antenna much reduced in size. Prothoracic shield with an anteriorly projecting, angular process on each side. Legs 2-segmented; lacking claws, instead with a single terminal seta. Last abdominal segment with median portion of venter covered with a large quadrate patch of stout, caudally directed, spine-like setae; venter with a single, broad, caudal, median lobe.

Native range

Mexico. This species is known from the transvolcanic belt of central Mexico where it occurs at elevations between 1,000 and 1,600 meters (Edmunds, 1994).

Plant host(s)

None. This species feeds on dung as both an adult and larva (Price and May, 2009). There are no records of this scarab feeding on live plant tissues.

Life history

(Price and May, 2009): Like the majority of Phanaeus species, P. daphnis feeds on mammalian dung. The droppings of omnivores such as swine and humans are preferred, but the dung of herbivores such as cattle is readily accepted. Carnivore dung is the least preferred. Females locate dung by flying low over the ground, then land near (but rarely on) the feces. Using their front legs, females move a portion of the dung up to 18 m (59 ft) from the original site. Unlike most other Phanaeus species, the P. daphnis beetle does not aid in moving the dung. Dung is deposited in a burrow and formed into a pear-shaped brood ball. The brood ball is impregnated with an egg and then enclosed in clay (perhaps to prevent dessication). No further parental care takes place, though adults may continue to inhabit the burrow. In the native range, breeding takes place between June and November. Adult females lay approximately 12 eggs over 180 days. Adults are diurnal.

Pest potential

None. This species recycles dung and is beneficial for ranching and farming in Hawaii. As 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 occur in Hawaii or Guam.

Status in Hawaii

Recorded, not established. This species was intentionally released in Hawaii with the goal of controlling populations of the horn fly (Haematobia irritans). Introductions were made in 1954 at Parker Ranch on Big Island (Weber, 1954). In 1955, further introduction attempts were made at Molokai Ranch on Molokai and Waimea on Kauai (Weber, 1955). Despite these release attempts, the beetle apparently never established self-sustaining populations (Nishida, 2002).

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 released but did not establish.

Similar species

With their distinctive shape and coloration, major males of the Phanaeus daphnis are unmistakable. However females and minor males could be confused with the green form of Canthon pilularius. P. daphnis can be separated from C. pilularius by examination of the rear tarsi (P. daphnis lacking rear tarsal claws versus C. pilularius with rear tarsal claws) and the apex of clypeus (P. daphnis clypeal apex rounded versus C. pilularius with clypeus distinctly emarginated).

Other names (synonyms)

Phanaeus coerulus Bates, Phanaeus herbeus Bates, Phanaeus substriolatus Balthasar, Phanaeus tricornis Olsoufieff

Report your observation

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Phanaeus daphnis major male; photo by E.L. Engasser

Phanaeus daphnis major male; photo by E.L. Engasser

Phanaeus daphnis major male; photo by E.L. Engasser

Phanaeus daphnis major male; photo by E.L. Engasser

Phanaeus daphnis major male; photo by E.L. Engasser

Phanaeus daphnis major male; photo by E.L. Engasser

Phanaeus daphnis major male; photo by E.L. Engasser

Phanaeus daphnis major male; photo by E.L. Engasser

Phanaeus daphnis minor male; photo by E.L. Engasser

Phanaeus daphnis minor male; photo by E.L. Engasser

Phanaeus daphnis minor male; photo by E.L. Engasser

Phanaeus daphnis minor male; photo by E.L. Engasser

Phanaeus daphnis female; photo by E.L. Engasser

Phanaeus daphnis female; photo by E.L. Engasser

Phanaeus daphnis female; photo by E.L. Engasser

Phanaeus daphnis female; photo by E.L. Engasser

Phanaeus daphnis male genitalia, caudal view; photo by E.L. Engasser

Phanaeus daphnis male genitalia, caudal view; photo by E.L. Engasser

Phanaeus daphnis male genitalia, lateral view; photo by E.L. Engasser

Phanaeus daphnis male genitalia, lateral view; photo by E.L. Engasser

distribution map for Phanaeus daphnis

distribution map for Phanaeus daphnis