Mariana Eight-spot Butterfly

Adult Mesb

The Mariana eight-spot butterfly (Mesb), also known as Hypolimnas octocula marianensis, is a Guam endemic that was listed as endangered under the Endangered Species Act in 2015 and is legally protected.

  • Mariana Eight-spot Butterfly Adult

    Adult Mesb

    A butterfly of the Nymphalidae family, the Mariana eight-spot butterfly is known solely from the islands of Guam and Saipan. Believed to be extirpated from Saipan, Guam remains its only known home in the world. The butterflies are primarily orange and black. Males are smaller than females and are mostly black with an orange stripe running vertically across the wings, in which the hindwings have small black dots. Females are more orange in color and have black bands across the top margins of both wings. Along the inner margins of the black bands are white spots.

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  • Mariana Eight-spot Butterfly Egg

    Mesb Eggs w Poss Parasitism (2)

    The eggs of the eight-spot butterfly are hard to spot; therefore, visitors are asked to take care near its hostplants: Elatostema calcareum and Procris pedunculata. Adult females tend to lay their eggs on the edge of host plant leaves, and in clusters of one or two. The eggs are generally a light green in color, and although some darkening is normal as the caterpillar forms, the blackened egg pictured is believed to have been parasitized by a species of parasitic wasp native to the island - either Telenomus sp. or Ooencyrtus sp.

  • Mariana Eight-spot Butterfly Caterpillar

    Photo of Mesb Caterpillars

    The caterpillar larvae of the eight-spot begin life lacking much color and appear slightly clear. As the caterpillars mature, their bodies turn black and their spikes turn red. A black head differentiates this species from similar-looking caterpillars, including Hypolimnas bolina and H. anomala.

  • Mariana Eight-spot Butterfly Chrysalis

    Mesb Chrysalis

    Once an eight-spot caterpillar pupates, it transforms into a chrysalis that is brown in color with brown spikes.

  • Elatostema calcareum

    GNWR Wild - Elatostema

    One of only two native host plants for the Mariana eight-spot butterfly, Elatostema is a vital food source for the caterpillars of this endangered species. A forest herb, Elatostema is only found on karst substrate, often on limestone boulders. Also known as Tupun Ayuyu in Chamorro, or 'cane of the coconut crab', these plants also act as a critical water source for coconut crabs during the drier times of the year. Used for generations as a medicinal plant by "Suruhanas" to treat various ailments, the collection of this plant must be balanced with the role it plays for this endangered species; therefore, limited collection of Elatostema is permitted with a pre-approved plant collection permit AND under the supervision of a trained staff member who is able to identify the eggs and caterpillars of this protected species and direct visitors to plants suitable for collection.

  • Procris pedunculata

    Procris

    One of only two native host plants for the Mariana eight-spot butterfly, Procris is a vital food source for the caterpillars of the endangered Mariana eight-spot butterfly. A forest herb, it is found mainly on karst substrate, often on limestone boulders. Compared to Elatostema, Procris is slightly woody and also appears to fair better in sunny areas with less water. This plant has also been observed growing as an epiphyte on trees.

  • Parasitic Wasp

    Parasitic Wasp

    This parasitoid wasp is of the Ichneumonidae family, possibly Echthromorpha sp. These wasps are one of the many threats to the Mariana eight-spot butterfly, as they attack larvae and pupae, placing an egg inside the host - which eventually kills it.

  • Habitat Restoration

    NPS FWS Outplanting Photo

    The U.S. Fish and Wildlife Service and National Park Service, in coordination with FWS ecological services, developed a collaborative partnership to recover the Mariana eight-spot butterfly on Park Service and Refuge lands. This joint partnership resulted in increased knowledge of propagation methods and approximately 200 host plants planted in Park lands where habitat for this endangered species did not exist before.

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