Drones Deliver Millions Of Mosquitos to Prevent Bird Extinctions In Hawai‘i

Forbes

10-06-2025

Mosquito 'birth control' delivery efforts mark a major technological advance for conserving critically endangered Hawai'ian honeycreepers.
'Ākohekohe (Palmeria dolei), or crested honeycreeper, is endemic to the island of Maui in Hawaiʻi. ... More The ʻākohekohe is susceptible to mosquito‐transmitted avian malaria and only breeds in high‐elevation wet forests. It is critically endangered with fewer than 2,000 individuals alive today. (Via USFWS / public domain.)
In a brilliant demonstration of multidisciplinary collaboration, a conservation program to save Hawai'i's critically endangered native bird species has taken another step forward. After a team of scientists developed sterile male mosquitoes, the next challenge was to safely deliver them to where they would be most effective in Hawai'i.
Sterile male mosquitoes are created by infecting them with the bacteria, Wolbachia. This bacteria, which naturally occurs in many wild insect species, interferes with reproduction in mosquitoes by 'sterilizing' the males when introduced into mosquito populations like Aedes aegypti. When sterile male Wolbachia-infected mosquitoes mate with invasive wild female Aedes aegypti mosquitoes, the resulting eggs cannot be fertilized and thus, cannot hatch, thereby reducing the mosquito population.
Wolbachia is a maternally transmitted bacterium, where female Wolbachia-carrying Aedes aegypti pass ... More the bacterium to their offspring, thus generating a stable line of Wolbachia-Aedes mosquitoes. Rearing this line of mosquitos in captivity allows humans to easily produce large numbers of incompatible male Wolbachia-Aedes mosquitoes for release. (Credit: The National Environment Agency of Singapore / Public Domain)
Male mosquitoes (regardless of whether they carry Wolbachia) do not bite or transmit disease, and feed only on plant juices and nectar for survival and energy. On the other hand, female mosquitoes do bite because they need a fresh blood meal to produce eggs. Additionally, because Wolbachia-Aedes mosquitoes are not genetically modified, and because Wolbachia bacteria naturally occur in 60% or more wild insects, these mosquitoes are safe.
Where did these 'sterile' male mosquitoes originate?
'These males are descendants of mosquitoes originally collected from Hawai'i and it has taken multiple mosquito generations to breed up enough IIT mosquitoes to supply the project's needs,' said scientific outreach specialist Emma Shelly, who works as the Outreach Manager with Birds, Not Mosquitoes. This is a multi-agency partnership, spearheaded by the American Bird Conservancy, that is working to protect native Hawaiian honeycreepers from extinction caused by avian diseases, particularly avian malaria, transmitted by invasive mosquitoes.
The effort uses the Incompatible Insect Technique (IIT) as a biological 'birth control' method to reduce the spread of mosquito-borne diseases by reducing local mosquito populations by more than 80% (ref). It has been used successfully in a wide range of places and situations around the world to control a variety of mosquito-borne diseases, ranging from dengue fever to malaria.
Do free-roaming female mosquitoes prefer to mate with these IIT male mosquitoes?
'So all things being equal, matings would occur at random,' Ms Shelly told me in email. 'But all things aren't equal because the project is heavily skewing the odds in favor of the incompatible males by releasing them in such large numbers that the wild male mosquitoes are overwhelmed. In this scenario, wild females have significantly more opportunities to encounter IIT males and mate with them.'
This technique is known as 'overflooding' and the 'overflooding ratio' (how many IIT males it takes to overwhelm wild males in a given area) is a key component of the project. In Hawai'i, that ratio is 10:1.
Not only can drones deliver missiles to protect beleaguered civilians from Russian terrorists, but drones can also deliver pods full of IIT male mosquitoes to protect critically endangered Hawai'ian honeycreepers from avian malaria. But the drones used in these biological battles are not the same as those used against Russia, as you might have guessed.
'The drones we use are more common for activities requiring a moderate payload for a drone, like LiDAR, magnetometers, or cinema cameras. They are usually somewhat larger and fly much slower,' Adam Knox, drone pilot and Aerial Deployment of Mosquitoes Project Manager for American Bird Conservancy, told me in email. 'One of the drones we use, the Freefly AltaX is used for movies (can carry a RED Epic or similar) as well as aerial ignition deployment for controlled wildfire burns.'
What makes these particular drones particularly well-designed to carry out their mosquito-delivery job?
'The drones needed to have adequate range and endurance to reach the 3000 acre site that extends over mountainous terrain carrying the payload system and then return home, so much of the testing has been focused on demonstrating this,' Mr Knox explained in email.
Are these drones guided by autopilot or by humans?
'Both,' Mr Knox replied in email. 'A human pilot flies the aircraft manually during takeoffs and landings to precisely navigate around hazards in the forest, then once above the tree canopy, the aircraft is switched into an autopilot mode which allows it to carry out the preplanned mission as the pilot monitors the flight.'
The male mosquitoes are delivered in biodegradable pods. Each drone carries up to 23 mosquito pods in one flight, and each pod contains about 1,000 insects.
'The pods are made of a sterilized biodegradable paper pulp and are not reusable,' Mr Knox explained in email. 'Once released from the air, they fall to the forest floor where they provide protection to the mosquitoes until they're ready to fly away. The pods then begin to break down once exposed to the elements.'
A drone carrying a biodegradable mosquito pod, loaded and ready to deliver. (Credit: Adam Knox, ... More image appears here courtesy of the American Bird Conservancy.)
This effort is the first known instance of specially-designed mosquito pods being dropped by drones. One of several pod design challenges that had to be met before the drone delivery service could be launched was the pods needed to maintain a controlled temperature. Unlike other insect species that have been released directly from drones in other parts of the world, these male mosquitoes are fragile and require containment in temperature-controlled pods.
'It's extremely exciting to have reached this project milestone,' Mr Knox remarked in email. 'The first drone deployments took place in April 2025. It took a lot of hard work and reliance on strong partnerships to reach the point where we could successfully demonstrate the utility and potential of drone aircraft as a tool for this important work, especially in one of the more challenging environments in the world.'
The mosquito deliveries occur over thousands of acres of remote, mountainous terrain that have significant elevational changes, strong winds, and frequent rain. The drones and their release systems had to be tested in these demanding conditions to validate their ability to carry out the basic components of the mission.
Can you imagine dropping mosquitoes in this landscape without falling to your death? Aerial view of ... More the rugged terrain, steep walls and waterfalls at Koolau Forest Reserve East Maui, Hawaii. (Credit: Forest and Kim Starr / CC BY 3.0 US)
Originally, mosquito deliveries began in 2023 with twice weekly helicopter deployments into remote forests on Maui and Kaua'i, but drone deployments are so much safer for the humans delivering the mosquitoes.
'This opens up a lot of possibilities now and into the future,' Mr Knox pointed out. 'With a drone, we have more flexibility with deployment timing in areas that generally have very unpredictable weather, and it's safer because no humans need to ride in the aircraft as pilot and crew to deploy the mosquitoes.'
Your job looks like it's fun. Is it?
'My parents got me a Tyco Wild Thing as my first RC car when I was probably 5 or 6 years old and since then I have been into the RC hobby on and off throughout my life, spanning cars, planes, helicopters and drones,' Mr Knox replied in email. 'To be able to have my professional pursuits overlap with a hobby that brings me joy is something many only dream about so I feel incredibly lucky to have the opportunity to apply this skillset and knowledge toward helping some of the most endangered wildlife on the planet.'
"What we're doing is difficult and it has required a lot of long days for dozens of people scattered across the country working together over multiple years now,' Mr Knox replied in email. 'It's been worth every ounce of effort with what we've been able to learn while getting these specialized IIT mosquitoes out into some of the most challenging landscapes imaginable in order to give these birds a fighting chance at recovery.'
Even as these IIT mosquitoes are being delivered to their targets, are there other conservation efforts ongoing?
'Yes, there are,' Mr Knox replied in email. 'The San Diego Zoo Wildlife Alliance has two facilities in Hawai'i where small populations of several endangered bird species are being kept and captively bred. The sooner mosquitoes are suppressed, the sooner these critically endangered birds can be returned to the wild and begin to re-establish themselves.'
Whilst the IIT mosquito effort is currently the best tool we have for controlling invasive disease-carrying mosquitoes, it works hand in hand with other conservation efforts being led on the ground by Birds, Not Mosquitoes partners, including habitat restoration and invasive species and predator control.
A critially endangered Hawai'ian Kiwikiu (Pseudonestor xanthophrys) or hookbilled honeycreeper. ... More There are fewer than 200 of these birds remaining. (Credit: Robby Kohley, image appears here courtesy of the American Bird Conservancy.)
The mosquito, Aedes aegypti, was initially introduced to the Hawaiian Islands sometime after 1882 by whaling ships, so any ecological role these insects may fill either as prey or pollinators is a recent development. Which is another way to say that it is extremely unlikely that any native bird species has become dependent upon them as a critical food resource. But this invasive mosquito species is quite efficient at transmitting a variety of debilitating diseases to humans, such as dengue, chikugunya, Zika virus, and malaria, just to name a few.
Originally, the Aedes aegypti mosquito was restricted to Hawai'i's lower elevations, which allowed some of Hawai'i's honeycreepers to live at higher elevations and thus survive. However, climate change has allowed mosquitoes to expand their range upwards, so now all of Hawai'i's remaining native bird species are in danger of vanishing forever.
'Without significantly reducing invasive mosquito populations, multiple native bird species will disappear forever in the near future,' said Chris Farmer, the American Bird Conservancy's Hawai'i Program Director.
How many native Hawai'ian bird species have been driven extinct by avian malaria so far?
'At least 33 species of honeycreeper are now extinct, and many of the 17 that remain, including the Kiwikiu and ʻĀkohekohe on Maui, and ʻAkekeʻe on Kauaʻi, are highly endangered,' Dr Farmer replied. 'Last year, the ʻAkikiki became functionally extinct in the wild, and mosquitoes could cause other species to quickly decline and vanish if no action is taken.'
The ʻakikiki (Oreomystis bairdi), also called the Kauaʻi creeper, is now functionally extinct, ... More thanks to avian malaria spread by invasive mosquitoes. (Credit: Robby Kohley, image appears here courtesy of American Bird Conservancy.)
'Reducing invasive mosquito populations is absolutely critical in preventing the extinction of Hawai'i's vulnerable honeycreepers,' Dr Farmer continued. 'We have the technology to break the avian disease cycle in Hawai'i, and a fighting chance to restore populations. We are the generation that can save honeycreepers like Maui's Kiwikiu, and with a population of less than 150 individuals, these drone and mosquito suppression advancements have come just in time.'
I highly recommend that you watch this moving video, Vanishing Voices, which shows how ABC is working with its Birds, Not Mosquitoes partners to prevent the extinction of the iconic native bird species in Hawai'i. This wonderful, hopeful video shares the gorgeous songs of these vanishing birds.
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