Mosquitoes dropped by drone: Inside Hawaii’s daring ecological experiment. Know all about it

In June, dozens of biodegradable pods fell from the sky over the forests of Hawaii. Each one, delivered by drone, contained about 1,000 mosquitoes. These weren't ordinary mosquitoes — they were non-biting, laboratory-bred male mosquitoes with a pervasive bacterium that renders eggs unable to hatch when the males mate with wild females. The expectation is that they will suppress the archipelago's invasive mosquito population, which is wiping out native birdlife, including rare Hawaiian honeycreepers.

The birds, which are also important pollinators and seed dispersers and central figures in Hawaiian society, are in trouble. There used to be over 50 known honeycreeper species in Hawaii, but now there are only 17 remaining, most of which are endangered. The 'akikiki, a gray, small bird, became functionally extinct in the wild last year, and fewer than 100 of the yellow-green 'akeke'e are thought to survive.

Development and clearing have taken their toll, but avian malaria, which is transmitted by mosquitoes, is the "existential threat," according to Dr. Chris Farmer, American Bird Conservancy's Hawaii program director. The insects did not occur naturally in Hawaii, but in 1826 were first seen, probably inadvertently brought over in whaling ships. "They created waves of extinction," Farmer was quoted saying to CNN, as most Hawaiian birds, including the honeycreepers, had no immunity to the disease. Since the mosquitoes are adapted to the warmer tropical environments at the lower elevations of Hawaiian islands, the rest of the honeycreepers made their sanctuary high up in the islands' mountains, such as Maui and Kauai, he explains.

Now that's reversing. "With climate change, we're having warmer temperatures and we're observing the mosquitoes climbing up the mountains," he explained further. “(In Kauai) we're observing the bird populations there just totally decline. It's a steady progression of mosquitoes climbing up as temperatures permit them and the birds being driven further and further up until there's no longer habitat left that they can survive in. If we do not interrupt that cycle, we will lose our honeycreepers," he said.

Conservationists have been looking for a way to manage mosquito numbers and offer a lifeline to the honeycreepers. But mosquitoes on a landscape level are hard to control, according to Farmer, who describes how the application of pesticides, for example, would also harm native insect populations like damselflies and fruit flies that are crucial to ecosystems. Since mosquitoes are also such a significant health risk to humans, transmitting human malaria, dengue fever and the zika virus, among others, scientists have been researching the issue for decades and invented numerous solutions, among them the incompatible insect technique (IIT).

“We have a rough estimate for how many mosquitoes there are in the wild, and we try to release 10 times as many of these Wolbachia mosquitoes, so (that they) find these females and are able to mate with them, and then their eggs don’t hatch,” Farmer was quoted saying. “Right now, we’re releasing 500,000 mosquitoes a week on Maui and 500,000 mosquitoes a week on Kauai,” he addded, using both drones and helicopters.