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These Rare Damselflies Find Love With a Twist in Fog City

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Most damselflies prefer sunny spots, but the quirky San Francisco forktail damselfly digs the fogginess of its hometown. When they hook up, they do it in style — linking their delicate bodies in a heart shape, then flying tandem for an hour or more after.


It’s a classic summer day in San Francisco — foggy.  

But for the quirky San Francisco forktail damselfly, the weather is perfect for finding love. 

Damselflies are dragonfly cousins. They’re both odonates, a group of flying insects. When they’re at rest, most damselflies neatly fold their wings back, while dragonflies keep theirs outstretched.

Male San Francisco forktail damselflies aren’t afraid to show some flair — they’re decked out in turquoise. Young females sport a soft pink. Down in the reeds, the courtship begins. The male flies up to the female. He then uses claspers at the end of his blue body to hold the female just behind her head.

In what looks like an advanced yoga pose, the female curves her entire body forward. She hooks the tip of her abdomen to his midsection. The male leaves nothing to chance. Inside her body, he carefully scrapes out the sperm from any previous partners. Then he deposits his own. 

When the mating is over, the pair stays connected, sometimes for more than an hour. This keeps the other males at bay, and gives time for only his sperm to fertilize her eggs. When the female’s ready to lay her eggs, the pair moves close to the water. She slices tiny openings into these reeds with her ovipositor, a tube-shaped organ for laying eggs. She tucks them just under the plant’s surface — one at a time.

A couple of weeks later, the eggs hatch into voracious nymphs called naiads. They’ll spend a few months like this in the water. Naiads breathe through caudal gills, these leafy things on their backside. Just like these dragonfly naiads, they’ll climb out of the water, shed their exoskeleton, and eventually fly off.  

There are thousands of species of damselflies, but the San Francisco forktail is special — it’s one of just a few that thrive in a foggy, coastal climate. Researchers think their darker, more robust bodies may better absorb heat and help them stay warm in cool places. But a warming world is diminishing the fog that blankets this city.  Plus, the wetlands they lay their eggs in are disappearing. San Francisco forktail damselflies are now one of the rarest species of odonates in North America.

So researchers from the San Francisco Zoo are stepping in. They’ve figured out how to breed the San Francisco forktail in captivity, and are releasing and monitoring their populations. The number of these insects in the wild  is increasing. But will their efforts be enough? It’s too early to tell. 

San Francisco has long been home to dreamers, misfits, lovers. The work of these scientists is not just for biodiversity — it’s an attempt to save another colorful resident that calls this City by the Bay its home.

Heya Deep Lookers, it’s Laura — we all know caterpillars have a huge appetite.  But why is the very hungry caterpillar so dang hungry? Watch this fan favorite Deep Look episode to find out. Thanks, and enjoy!

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