The U.S. Fish and Wildlife Service has proposed more than 9,200 acres of critical habitat for a dozen species of Hawaiian picture-wing flies following an investigation into an earlier decision by a former high-ranking Bush administration official to set aside only 18 acres for the rare insects.

The decision was one of eight rulings called into question amid allegations that Julie MacDonald, a deputy assistant secretary at the Department of Interior, overruled scientists' recommendations and improperly influenced rulings to protect imperiled species under the Endangered Species Act.

The Fish and Wildlife Service last week reversed seven of the eight decisions following a federal investigation of actions by MacDonald, who resigned in May.

Hawai'i scientists who provided advice on protection measures expressed outrage when the 18-acre plan was announced in August, calling it "indefensible" and "ludicrous."

The latest proposed critical habitat rule "is a step in the right direction," said David Foote, a research ecologist for the U.S. Geological Service on the Big Island. "The original proposal was woefully inadequate, and any improvement is very much welcome. At this point it gives us something to work with so we can actually develop a recovery plan."

Hawaiian picture-wing flies are known as the "birds of paradise" of the insect world for the elaborate markings on their translucent wings and for their flamboyant courtship and territory-defense behaviors.

There are approximately 106 species of Hawaiian picture-wing flies, each specially adapted to a particular island and a specific habitat, ranging from desert to rainforest or swamp land. Their remarkable adaptive skills have given them a key role in the study of biology and evolution.

Foote said the flies are featured in biology textbooks, introducing students around the world to Hawai'i's fragile ecosystems.

"They are a wonderful example of why Hawai'i is unique and why it's important to save our biodiversity," he said.

The insects breed only on a single or a few related species of plants, some of which are also listed as threatened or endangered.

The new proposal identifies 32 habitat units totalling 9,238 acres on O'ahu, the Big Island, Maui, Moloka'i and Kaua'i.

"During the public comment period on the previous proposal, the service received comments and data from peer reviewers that has enabled us to increase our scientific knowledge and improve on the previously proposed critical habitat designations for picture-wing flies," said a statement from Patrick Leonard, Pacific Islands field supervisor for the Fish and Wildlife Service.

Federal lands comprise 47 percent of the total, including 3,604 acres in the Kona Forest Unit of Hakalau Forest National Wildlife Refuge and 752 acres in Hawai'i Volcanoes National Park.

State lands comprise 26 percent, or 2,330 acres, of the proposed critical habitat, while 1 percent, or 128 acres, are on City & County of Honolulu land. The public land already is part of forest or natural area reserves.

Twenty-six percent, or 2,424 acres, are on private land. Most of the private acreage is managed by The Nature Conservancy of Hawai'i in the Honouliuli Preserve in the Wai'anae Mountains and on Moloka'i.

The Kaua'i habitat is in Koke'e and the Maui habitat in Pu'u Kukui. In addition to Hakalau and the national park, other proposed picture-wing fly habitat on the Big Island is in the Kohala Mountains.

The Fish and Wildlife Service said future conservation efforts will focus on monitoring existing populations of the 12 species of picture-wing flies and controlling threats, which include habitat degradation by pigs and other wild animals, loss of host plants, and impacts of nonnative insect predators and parasites, including ants and wasps.

"Critical habitat" is a term in the Endangered Species Act that refers to geographic areas containing features essential for the conservation of a threatened or endangered species and may require special management considerations or protection.

The designation of critical habitat does not affect land ownership, establish special conservation areas or require implementation of recovery measures by the landowner.

However, federal agencies that undertake, fund or permit activities that may affect critical habitat are required to consult with the service to ensure such actions do not adversely affect those sensitive areas.

Reach Christie Wilson at cwilson@honoluluadvertiser.com.