Planes zigzag over Los Angeles dropping sterilized male flies. (via FlightAware)

Up in the sky! It’s a bird! It’s a plane! It’s … an irradiated male fly?

Every day over Los Angeles, small planes circle the skies dropping sterilized male flies to combat invasive Mediterranean fruit flies. You can see their symmetrical flight patterns in flight trackers, like the one depicted below.

A Medfly drop over Los Angeles in April 2021.
Gif created from animation by FlightAware.

In the 1980s, when Medfly outbreaks threatened California’s agricultural industry, officials authorized widespread aerial spraying of malathion. The insecticide shattered the fly’s nervous system, but also unnerved many Californians, who accused then-Gov. Jerry Brown of poisoning them. Today — with Medfly populations suppressed but still not eradicated — the preferred method of control is the continual release of radioactively sterilized male flies, ensuring that their female partners have no offspring. Even that program occasionally causes alarm. During the 2020 summer protests, some mistook the drops for surveillance missions.

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“The greatest economic disaster California has ever faced.” Retro Report did a nice little documentary on the battle against the Medfly in 2017. 👉 YouTube (~10 mins)

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