State appeals court backs mosquito suppression plan to save Hawaii’s rare birds

The state plans on releasing thousands of bioengineered mosquitoes as “birth control” in Maui forests, hoping it will curb insect populations and slow the spread of avian malaria.

by Jeremy Yurow, Court House News, April 15, 2025

HONOLULU (CN) — A Hawaii Intermediate Court of Appeals panel, siding with the state and bird advocates, found that a mosquito suppression biopesticide project designed to protect endangered native birds from avian malaria can continue. 

Maui resident Tina Lia and her nonprofit Hawaii Unites challenged the state's Department of Land and Natural Resources' environmental assessment and the Board of Land and Natural Resources' finding of no significant impact for the proposed mosquito control project on Maui, which involves the release of novel bioengineered mosquitos, intended to curb the insects’ population to prevent them from spreading avian malaria.

But in its decision, the appeals panel primarily agreed with the state's environmental court, upholding most of its ruling that the Hawaii was not required to prepare a more extensive environmental impact statement for the project.

Hawaii Unites argued that scientific studies raised substantial questions about whether the mosquito suppression technique would have significant environmental effects. They also said that the environmental assessment failed to adequately address mitigation measures and biosecurity protocols.

The three-judge panel disagreed, finding that these issues were addressed in the environmental assessment, citing specific chapters, tables and appendices in their ruling.

"BLNR's acceptance of the EA and issuance of the FONSI was supported by substantial evidence in the record. BLNR's mixed finding and conclusion that DLNR's proposed action will not have a significant effect and will not require preparation of an EIS was not clearly erroneous," the panel said.

Despite upholding the finding of no significant impact, the order agreed with Hawaii Unites that the department's final environmental assessment did not comply with Hawaii Administrative Rules. 

This rule requires that when agency groups comment responses under topic headings, the names of commenters who raised issues under each topic heading must be clearly identified, and all comments must be appended in full to the final environmental assessment.

The panel, consisting of Acting Chief Judge Katherine G. Leonard, Judge Keith K. Hiraoka and Judge Clyde J. Wadsworth, directed the department to revise its environmental assessment in accordance with Hawaii administrative rules.

While the procedural aspects of the environmental assessment must be corrected, the substantive findings allowing the mosquito suppression project to move forward remain intact — a development attorney Maxx Phillips described to Courthouse News via a written statement as "a huge win for Maui's endangered birds, who have been dying from mosquito-borne avian malaria."

"The courts have once again made clear that we won't stand by while avian malaria pushes these irreplaceable species to the brink. Our manu deserve a fighting chance," Phillips, Hawaii State Director for the Center for Biological Diversity and attorney representing American Bird Conservancy, which intervened in the case, added, using the Hawaiian word for birds.

As with many other diseases, mosquitoes are significant vector in the transmission of avian malaria between the birds. The invasive southern house mosquito is currently the biggest threat to Hawaii’s birds, who have no natural immunity to the disease the mosquitoes transmit.

"This decision reinforces what we've known all along — Hawaii is on solid legal and scientific ground in its effort to save native forest birds from extinction," Phillips said.

The panel, in their ruling issued Monday, also addressed Hawaii Unites' argument that the lower environmental court should have considering additional evidence, including a declaration by Lia and printouts from the website flightaware.com. The state had objected to this evidence, citing hearsay and lack of personal knowledge.

"The environmental court seems to have considered Lia's declaration and printout but characterized them as raising 'mere possibilities.' This was neither wrong nor an abuse of discretion," the panel wrote.

But the panel added, "courts are hesitant to substitute their judgment for an agency's when the agency uses its expertise and experience to make a mixed determination of law and fact."

The Birds, Not Mosquitoes program — a collaborative proposal by state agencies and other government, private and nonprofit organizations including U.S. Fish and Wildlife, the University of Hawaii, and the American Bird Conservancy, among others — would implement the “incompatible insect technique” as a form of mosquito birth control.

The technique utilizes mosquitoes infected in a lab with the naturally occurring Wolbachia bacteria, which affects insect reproduction. The infected pests are unable to produce viable offspring with either unafflicted insects or those with a different strain of the bacteria. According to the program, only male Wolbachia-treated mosquitoes, which do not bite or feed on blood, would be released into the Maui forests.

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AG News Release: 2025-54 APPEALS COURT CONFIRMS FINAL ENVIRONMENTAL ASSESSMENT SUFFICIENT IN HAWAIʻI’S FIGHT TO SAVE ENDANGERED BIRDS

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BIN: State wins victory in battle to save endangered native birds from scourge of avian malaria : Big Island Now