Hi Deep Look and KQED Science Fans, The pools of sticky oil known as the La Brea Tar Pits in Los Angeles, California, are a paleontologist’s dream. Over the past 50,000 years, ice age animals, plants, and insects have been trapped and preserved in the tar pits, offering scientists a unique window into the past. But fossils aren’t the only fascinating discovery there. Scientists have also uncovered an insect that thrives in this harsh environment: the petroleum fly. These resilient flies have adapted to life in the pits, which have claimed the lives of countless other animals. The adult flies can walk effortlessly across the oily substance, mate, and lay eggs that hatch into tiny larvae. The larvae depend on the oil to stay moist. Without it, they would die! To film this unusual insect, we climbed down into one of the pits to get a closer look. We hope you enjoy learning about these slick flies in our video and in this week’s newsletter.
This tiny petroleum fly larva swims with ease in the same oily, sticky substance that trapped dire wolves, mammoths and saber-toothed cats tens of thousands of years ago. The larva breathes through snorkel-like tubes on its rear end, which is ringed with hairs that keep it afloat.
😋 Petroleum fly larvae have a big secret. They can eat asphalt and survive. Most people know this substance as tar, but scientists call it natural asphalt. To make a road, you would mix it with sand, gravel and rocks. It’s still a mystery as to how larvae can “digest” or clear out this dark, sticky substance. ☠️ If we ate asphalt in the same proportions as petroleum fly larvae do, we could get cancer. 🧴 Larvae use the oil as an essential moisturizer. They would dry out if they didn’t have contact with the oil. 🦟 Larvae feed on insects that have been caught in the asphalt. Dragonflies and other insects that spend their lives near ponds often mistake shiny pools of asphalt for water. ⛸️💕 Adult flies are able to skate – and mate – on the asphalt pools. Their feet don’t get stuck. But if any other body part touches the sticky liquid, they’re out of luck.
PLAY
Name That Critter!
This fly scuba-dives in the harsh waters of California's Mono Lake, which is three times saltier than the ocean and too caustic for most animals. Surprisingly, it remains dry while embarking on a quest for tasty algae and a place to lay its eggs. What is it? Find the answer at the bottom of this newsletter.
PATREON
Support DEEP LOOK!
Josh Cassidy, Deep Look’s lead producer and cinematographer, films outdoor shots at the La Brea Tar Pits among replicas of mammoths that roamed the Los Angeles area tens of thousands of years ago.
Help Deep Look start 2025 strong! Support us on Patreon so we can keep making fascinating videos about the tiny dramas playing out every day in the natural world. Patreon is a monthly subscription-based platform that Deep Look uses to connect with fans. With your monthly support, you get exclusive behind-the-scenes content and swag like stickers, T-shirts, mugs and more. Join Deep Look’s Patreon today for as little as $3 per month, and help us continue our mission to provide a deeper understanding of science and nature, and to inspire the next generation of biologists and entomologists!
We hope you enjoyed this week’s newsletter. Thank you for subscribing! KQED’s Deep Look and Science Teams
ANSWER TO NAME THAT CRITTER
Alkali fly! Alkali flies have physical adaptations that allow them to survive in the harsh waters of California’s Mono Lake. Their bodies are covered in a waxy substance to counter the high concentration of sodium carbonate in the lake. They also have an impressive amount of hair, which helps them form a protective air bubble. Find out more in our video: This Daring Fly Swims in a Shimmering Bubble Shield
