Blackburn's Sphinx Moth

Manduca blackburni

Description

The Blackburn's sphinx moth is Hawaii's largest native insect, with a wingspan of up to 5 in (12 cm). It has long, narrow forewings and a thick, spindle-shaped body tapered at both ends. It is grayish brown in color, with black bands across the top margins of the hind wings, and five orange spots along each side of the abdomen. The larva is a large "hornworm" caterpillar, with a spine-like process on the upper surface of the eighth abdominal segment. The caterpillars can be either bright green or grayish. Both color forms have scattered white speckles on the back, a horizontal white stripe on the side, and diagonal stripes on the sides of segments four to seven.

Behavior

Larvae of the Blackburn's sphinx moth feed on plants in the tomato family (Solanaceae). Native host plants are popolo shrubs in the genus Solanum and the tree 'aiea (Nothocestrum latifolium ). Now, however, the most important food plants are non-native species such as tobacco (Nicotiana tabacum ), tree-tobacco (Nicotiana glauca ), eggplant (Solanum melongena ), and tomato (Lycopersicon esculentum ). Development from egg to adult can occur in as few as 56 days, but pupae can also remain in a torpid condition in the soil for up to a year.

Habitat

The Blackburn's sphinx moth occurs in coastal, lowland, and dryland forest habitats in areas receiving less than about 50 in (120 cm) of annual rainfall. It has been collected from sea level to 2,500 ft (760 m).

Distribution

The Blackburn's sphinx moth has been recorded from the islands of Kahoolawe, Kauai, Oahu, Molokai, Maui, and Hawaii. It appears to have historically been most common on Maui.

Threats

Once relatively common, the Blackburn's sphinx moth has declined due to the clearing of its natural forest habitat through conversion into agricultural, commercial, and residential land-uses. Much habitat damage has also been caused by introduced mammalian herbivores, such as cows and goats. These damages have caused the loss of the native food plants of the Blackburn's sphinx moth. Very few specimens of the rare moth were seen after about 1940, and it was considered extinct. In 1984, however, a single population was discovered on Maui, in habitat located on private and State lands, including a natural reserve, areas used by the Hawaii National Guard for training, or land administered by the Department of Hawaiian Homelands. Subsequent monitoring continued to find small numbers of the rare moth on Maui. In 1997, another population of Blackburn's sphinx moth was discovered on the State-owned island of Kahoolawe. Subsequent surveys indicated a relatively large population, with animals discovered on about half of the plants of tree tobacco searched. In 1998, two small populations of unknown size were discovered on State land on the island of Hawaii. Because of its rarity, the Black-burn's sphinx moth is valuable in the commercial lepidopteran trade, and this may pose a risk to the species. It is also thought to be severely threatened by predation by introduced insects, such as the big-headed ant (Pheidole megacephala ). This may, in fact, may be the most serious ongoing threat to the survival of the Blackburn's sphinx moth and many other native insects of the Hawaiian Islands.

Conservation and Recovery

Listing of the Blackburn's sphinx moth as an endangered species has resulted in it becoming a protected species, and also encourages conservation by State government agencies on state-owned land. The most crucial conservation needs of this endangered moth are to preserve the remnants of its native-forest habitat, and to find ways of reducing the effects on predation by introduced ants and other insects.

Contacts

U. S. Fish and Wildlife Service
Regional Office, Division of Endangered Species
Eastside Federal Complex
911 N. E. 11th Ave.
Portland, Oregon 97232-4181
(503) 231-6121
http://pacific.fws.gov/

U. S. Fish and Wildlife Service, Pacific Islands
Ecoregion
300 Ala Moana Boulevard, Room 3-122
P.O. Box 50088
Honolulu, Hawaii 96850
Telephone: (808) 541-2749
Fax: (808) 541-2756

Reference

U. S. Fish and Wildlife Service. 1 February 2000. "Endangered and Threatened Wildlife and Plants: Determination of Endangered Status for Blackburn's Sphinx Moth from the Hawaiian Islands." Federal Register 65 (21): 4770-4779.