1335: "The Housefly That Didn't Drown"

HistoryPodcastScience
Written By JC

Interesting Things with JC #1335: "The Housefly That Didn't Drown" - A housefly slips beneath the surface. No drama, just biology...fine hairs, a bit of wax, and a bubble of air. It's not designed to dive, but sometimes, it doesn’t drown either.

Curriculum - Episode Anchor

Episode Title: The Housefly That Didn't Drown

Episode Number: #1335

Host: JC

Audience: Grades 9–12, college intro, homeschool, lifelong learners

Subject Area: Biology, Entomology, Zoology, Environmental Science

Lesson Overview

Students will:

  • Define how houseflies breathe and the function of spiracles and tracheae.

  • Compare the adaptations of houseflies and diving beetles for underwater survival.

  • Analyze the role of physical traits such as waxy hairs in survival.

  • Explain how biological adaptations enable unexpected forms of survival in nature.

Key Vocabulary

  • Spiracle (ˈspir-i-kəl) — Openings on a fly’s body that allow it to breathe; when submerged, these can be clogged by water unless protected by adaptations.

  • Tracheae (ˈtrā-kē-ˌē) — Tiny tubes inside insects that carry oxygen from the spiracles to their tissues.

  • Hydrophobic (ˌhī-drə-ˈfō-bik) — Describing surfaces that repel water; a key trait of the fly’s wax-coated hairs.

  • Physical Gill (ˈfi-zi-kəl gil) — An air pocket used by some aquatic insects to extract oxygen underwater.

  • Musca domestica (ˈməs-kə dō-ˈmes-ti-kə) — The scientific name for the common housefly, known for its resilience and adaptability.

Narrative Core

  • Open: Introduces the common housefly and its surprising ability to survive underwater.

  • Info: Explains the anatomy of the fly’s breathing system and the role of spiracles and tracheae.

  • Details: Describes the waxy, hairy surface that allows some flies to trap air and survive temporary submersion.

  • Reflection: Emphasizes how unseen biological features can offer critical survival advantages.

  • Closing: “These are interesting things, with JC.”

A house fly trapped in a water bottle still moving

Transcript

Most people don’t give houseflies much credit. Annoying? Absolutely. Dirty? Probably. But here’s something you might not expect—they can sometimes survive underwater.

We’re talking about the everyday housefly, Musca domestica (MUSS-kuh doh-MESS-ti-kuh). These little bugs are everywhere. They measure around a quarter of an inch (about 6 millimeters), buzz around your kitchen, and seem impossible to catch. What most folks don’t realize is that they’re built with some surprising gear—including what amounts to a built-in wetsuit.

Flies don’t have lungs. They breathe through tiny holes on their body called spiracles. Those spiracles connect to a network of tubes inside called tracheae, which move oxygen around. So if water clogs those holes, a fly should be in serious trouble. But it’s not that simple. The fly’s body is covered in super-fine hairs that are coated with a waxy substance. That wax traps a layer of air around the fly—like a bubble suit. And that bubble can keep water out long enough for the fly to make a comeback.

Back in 2006, researchers at the University of California ran tests to see how long houseflies could stay underwater. Most didn’t sink. They floated, belly-up, because they’re light and water-resistant. But even when they were pushed underwater, some managed to hang on. They used their hairy, waxy armor to trap air, waited it out, and—if they got lucky—got back to dry ground. Not all of them made it. But the fact that any of them did? That’s worth knowing.

This kind of trick isn’t exclusive to houseflies. The diving beetle, Dytiscus marginalis (DIE-tis-kus mar-jin-AL-is), has been doing it on purpose for centuries. It carries a supply of air under its wings, creating what scientists call a physical gill. It can dive, breathe through the bubble, and stay underwater for hours. It’s a more advanced version of what the housefly pulls off—only the fly doesn’t mean to do it. It just happens to be built in a way that buys it time.

So what does it mean? Sometimes survival comes down to the little things you can’t see. The housefly might seem like a pest, but it’s also a lesson in engineering. Tiny hairs, wax layers, and air pockets—none of it flashy, all of it essential.

Next time one of them bounces off your screen door, try to picture that same fly rolling out of a puddle it wasn’t supposed to escape. That’s not just luck—it’s biology at work.

These are interesting things, with JC.

Student Worksheet

  1. How do houseflies breathe without lungs?

  2. What role do the waxy hairs on a housefly’s body play in underwater survival?

  3. How did the 2006 study by the University of California test fly survival?

  4. Compare the housefly's accidental survival method with the diving beetle’s intentional use of a physical gill.

  5. Write a short paragraph explaining how a common insect like the housefly demonstrates advanced biological engineering.

Teacher Guide

  • Estimated Time: 45–60 minutes

  • Pre-Teaching Vocabulary Strategy: Use labeled diagrams and short animations to introduce insect anatomy (spiracles, tracheae).

  • Anticipated Misconceptions:

    • Students may think houseflies have gills or lungs.

    • They may assume all insects drown immediately in water.

  • Discussion Prompts:

    • How do natural adaptations influence an organism's chance of survival?

    • What human technologies mimic this kind of biological waterproofing?

  • Differentiation Strategies:

    • ESL: Provide bilingual glossary and labeled visuals.

    • IEP: Offer scaffolded worksheets with sentence starters.

    • Gifted: Invite research into other animals with unexpected survival traits.

  • Extension Activities:

    • Design a "fly wetsuit" model using hydrophobic materials.

    • Conduct a home experiment with water-repellent surfaces (with supervision).

  • Cross-Curricular Connections:

    • Physics: Study surface tension and buoyancy.

    • Engineering: Explore biomimicry in product design.

    • Environmental Science: Discuss resilience in changing ecosystems.

Quiz

Q1. What is the main function of a housefly’s spiracles?
A. They help it see underwater
B. They allow it to fly
C. They allow it to breathe
D. They protect it from predators
Answer: C

Q2. What substance coats the hairs on a housefly’s body?
A. Oil
B. Saliva
C. Wax
D. Mucus
Answer: C

Q3. What year did researchers test houseflies underwater?
A. 1999
B. 2006
C. 2012
D. 2020
Answer: B

Q4. What is a physical gill?
A. A tool used to catch fish
B. A method of flying through air
C. An oxygen-holding bubble used by some insects
D. A chemical in insect wings
Answer: C

Q5. How does the diving beetle stay underwater for hours?
A. It breathes water like a fish
B. It traps air under its wings
C. It doesn’t need oxygen
D. It swims faster than flies
Answer: B

Assessment

  1. Describe how the housefly’s anatomy helps it survive short-term underwater exposure.

  2. Why is it important to understand how small adaptations help organisms survive?

3–2–1 Rubric:

  • 3 = Accurate, complete, thoughtful

  • 2 = Partial or missing detail

  • 1 = Inaccurate or vague

Standards Alignment

  • NGSS HS-LS1-2: Students analyze how body structures relate to function, such as spiracles and tracheae in houseflies.

  • CCSS.ELA-LITERACY.RST.9-10.2: Determine central ideas of a scientific text (the function of hydrophobic hairs).

  • C3.D2.His.14.9-12: Analyze how context shapes scientific knowledge over time (e.g., 2006 study relevance).

  • ISTE 3a: Students plan and employ strategies for effective research to explore biological phenomena.

  • UK GCSE Biology AQA 4.1.1.1: Understanding cell structures and organism adaptations.

  • IB MYP Science Criterion B: Inquiring and designing investigations, such as studying insect survival adaptations.

Show Notes

This episode of Interesting Things with JC takes a closer look at an everyday insect that rarely earns admiration—the housefly. But through a surprising deep dive into its anatomy, listeners learn how the fly’s wax-coated hairs and air-trapping body can keep it alive even underwater. A comparison to the diving beetle highlights the diversity of survival strategies in nature. This lesson is highly applicable in biology classrooms, where it can serve as a bridge to broader topics like adaptation, biomimicry, and evolution. The unexpected resilience of the housefly also provides a compelling entry point into discussions about how nature engineers solutions we’re only beginning to understand.

References

JC https://jimconnors.org
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