A U.S. Fish and Wildlife Service recovery plan for the endangered Blackburn's sphinx moth proposes focusing efforts on 13 management units totaling 143,202 acres on six islands.

Most of the land is state-owned, but some private property is included in the units. The units on Kaua'i, Maui, Kaho'olawe, O'ahu, Lana'i and the Big Island are areas that either contain the moth or the plants necessary for the insect's survival. The plan, released yesterday, recommends fencing some of the plant populations to prevent trampling and uprooting by pigs, goats and deer; keeping nonnative insects and weeds out of the habitat areas; and introducing plants that host the moth's larvae.

The price tag for efforts to bring the moth back to the point where it could be removed from the federal endangered species list was estimated by the Fish and Wildlife Service at $5.58 million over the course of a number of years, although it was noted that other rare species also would benefit from the habitat protection.

The Blackburn's sphinx moth is Hawai'i's largest native insect, with a wingspan of up to 5 inches. A member of the family Sphingidae, it is grayish brown with black bands across the top margins of its hind wings and five orange spots along each side of its abdomen.

Considered to be extinct as recently as the late 1970s, it was rediscovered on East Maui in 1984, and there have been subsequent sightings elsewhere on Maui, the Big Island and Kaho'olawe.

Habitat loss, especially at low elevations, is largely responsible for the species decline, according to the Fish and Wildlife Service. More recent threats include introduced ants and parasitic wasps that prey on the moth's eggs and caterpillars, and the continued loss of its native host plants, which are dryland forest trees and certain flowering plants.

The recovery plan is available at www.fws.gov/pacific/pacific islands. The document also may be viewed at the Hawai'i State Library at 478 S. King Street.