A “bee fly” looks a bit like a bee, but it’s a freeloader that takes advantage of a bindweed turret bee’s hard work. The bees dig underground nests and fill them with pollen they collect in the form of stylish “pollen pants.” As the bees are toiling on their nests, the flies drop their own eggs into them. But the bees employ a tricky defense against the flies. SUBSCRIBE to Deep Look! null Please join our community on Patreon! https://www.patreon.com/deeplook DEEP LOOK is an ultra-HD (4K) short video series created by KQED in San Francisco and presented by PBS Digital Studios. See the unseen at the very edge of our visible world. Explore big scientific mysteries by going incredibly small. --- In the spring in California, male bindweed turret bees get into brawls with their peers as they search for a female to mate with. Males pile onto each other and form so-called “mating balls,” an inaccurate name, since no mating is occurring. Rather, the males are getting into fights. The female they’re vying for is caught at the bottom, and sometimes the battle is so intense the males accidentally kill her. But, if she survives, she and the male who won steal away and mate. Once they’ve mated, females dig through compacted dirt to make a nest underground, where they’ll lay their eggs. The majority of the world’s bee species – 70 percent – are ground-nesting. The bindweed turret bees in this video chose a dirt parking lot near the town of Winters, in the Central Valley. These native bees are known by the scientific name Diadasia bituberculata. Females tirelessly scoop earth with their mandibles, softening it by dousing it with nectar they collected earlier. They work side by side, but each is “queen” of her own castle. As they dig out their nest, they often build a turret at the entrance. These dirt towers usually aren’t vertical: Many of them are tunnel-like, with a sideways entrance. Others curve down. With their entrances facing away from the sky, the turrets protect the bees’ nests when bee flies start dropping their eggs from the air. --- What is another name for a bee fly? Bee fly is the common name for the more than 4,000 species of flies in the family Bombyliidae. --- How do bee flies parasitize bees? The Paravilla fulvicoma bee flies in our video drop their eggs into the nests of bindweed turret bees. When the fly’s egg hatches into a larva, it digs tiny hooks into a bee larva. But the bee larva doesn’t die. It grows by feeding on the pollen that its mother packed for it inside the nest. As the bee larva grows, the fly larva sucks it dry and kills it. Then the fly finishes growing into an adult and pushes up through the ground to emerge the following spring. --- How do you tell a bee fly from a bee? Even though bee flies have hairy bodies like bees, if you look closely, you can tell them apart. Bee flies have big eyes that cover a large area of their heads. And bee flies’ antennae are short compared to bees’ antennae. ---+ Find a transcript on KQED Science: https://www.kqed.org/science/1983618/this-fly-torpedoes-a-bindweed-bees-nest ---+ More Great Deep Look episodes: Busy Bees and Other Pollinators Playlist https://www.youtube.com/watch?v=XjOfbEWVBpE Honey Bees Make Honey ... and Bread?| https://www.youtube.com/watch?v=sAKkjD3nEv0 This Bee Gets Punched by Flowers For Your Ice Cream https://www.youtube.com/watch?v=rsUNxvXofgo Watch This Bee Build Her Bee-jeweled Nest https://www.youtube.com/watch?v=oPbH1YhsdP8 ---+ Shoutout! 🏆Congratulations🏆 to these fans on our Deep Look Community Tab to correctly answer our GIF challenge! @sarabjorck6546 @royalfelinetracygrant6113 @ZxI_Puma @98SST @onabikewithadrone See the challenge here: null ---+ Thank you to our Top Patreon Supporters ($10+ per month)! Burt Humburg Karen Reynolds Companion Cube Daisuke Goto David Deshpande Chris B Emrick Tianxing Wang Wade Tregaskis Laurel Przybylski Mark Jobes Kevin Judge Porkchop Cindy McGill Roberta K Wright Titania Juang El Samuels Rory B. Carrie Mukaida KW Jellyman Jessica Hiraoka Mehdi Noreen Herrington SueEllen McCann Louis O'Neill Nicolette Ray monoirre Jeremiah Sullivan Levi Cai TierZoo Elizabeth Ann Ditz Syniurge ---+ Follow Deep Look and KQED Science on social: https://www.tiktok.com/@deeplookofficial https://www.patreon.com/deeplook Instagram: https://www.instagram.com/kqedscience/ Twitter: https://www.twitter.com/kqedscience ---+ About KQED KQED, an NPR and PBS member station in San Francisco, serves Northern California and beyond with a public-supported alternative to commercial TV, radio and web media. Funding for Deep Look is provided in part by PBS Digital Studios and the members of KQED. #beeflies #nativebees #deeplook