# Stream Mayflies (*Heptageniidae*) Stream mayflies are tiny insects that live in clean, fresh water. They have delicate wings and can often be seen dancing above streams on sunny days. - **Category:** [Insects](https://www.snappit.app/explore/categories/insect) - **Rarity:** Common - **Danger:** 1/5 · Very low - **Habitat:** Freshwater streams ![Stream Mayflies](https://commons.wikimedia.org/w/index.php?title=Special:Redirect/file/Ephemeroptera_2.jpg&width=800) Photo: Richard Bartz , Munich aka Makro Freak, CC BY-SA 2.5 · [Wikimedia Commons](https://commons.wikimedia.org/wiki/File:Ephemeroptera_2.jpg) ## Appearance The Stream Mayflies has flattened, streamlined bodies adapted for fast-flowing water. They typically have two or three long, thread-like tails and prominent plate-like gills along their abdomen. Colors range from dull browns and greens to mottled patterns, helping them blend with riverbeds. ## Taxonomy - **Kingdom:** Animalia - **Phylum:** Arthropoda - **Class:** Insecta - **Order:** Ephemeroptera - **Family:** Heptageniidae ## Interesting facts - Adult mayflies have no functional mouthparts; they don't eat at all! - Mayfly eyes can be huge and divided, letting them see above and below water! - Some adult mayflies have two pairs of wings, but only use the front pair for flight! - They are the only insect group that molts after developing functional wings! ## Special abilities - **Grip Master:** Stream Mayflies can cling tightly to rocks because they have flattened bodies and strong claws that help them resist swift currents. - **Underwater Breather:** Stream Mayflies has feather-like gills along their abdomen that helps them extract oxygen directly from the water while submerged. - **Quick Change Artist:** Stream Mayflies can shed their skin one last time after they grow wings, which helps them become even better, fully mature fliers. - **Water Quality Sensor:** Stream Mayflies can indicate clean water because their delicate nymphs are highly sensitive to pollution, helping them act as natural monitors. ## Measurements & details - **Wingspan:** 10-30 mm - **Size:** 5-20 mm - **Lifespan:** 30-365 days - **Flight Speed:** 10 km/h - **Leg Count:** 6 ## Diet & Feeding Nymphs graze on tiny plants and decaying bits, while adults astonishingly do not eat at all! - **Age differences:** Nymphs are active feeders, but adults have non-functional mouths and do not eat during their short lives. - **Primary Foods:** algae, diatoms, detritus, decaying plant matter, fungi - **Foraging Method:** Grazing ## Ecological connections - **Eaten by:** [Brown Trout](https://www.snappit.app/explore/brown-trout) (*Salmo trutta*) — A key food source for many fish species. - **Eaten by:** [Barn Swallow](https://www.snappit.app/explore/barn-swallow) (*Hirundo rustica*) — Adults are caught mid-air by these agile birds. - **Eats:** Diatom (*Diatoma vulgaris*) — Nymphs scrape and feed on these microscopic algae. - **Eaten by:** [Common Green Darner](https://www.snappit.app/explore/common-green-darner) (*Anax junius*) — Dragonfly nymphs prey on mayfly nymphs in the water. ## Traits - [Social](https://www.snappit.app/explore/traits/social): Social animals live in organized groups, cooperating for survival benefits such as foraging, defense, and raising offspring. - [Herbivorous](https://www.snappit.app/explore/traits/herbivorous): This trait characterizes organisms whose diet consists entirely or primarily of plant material. - [Insectivorous](https://www.snappit.app/explore/traits/insectivorous): This trait identifies organisms whose diet primarily consists of insects and other small invertebrates. - [Diurnal](https://www.snappit.app/explore/traits/diurnal): Diurnal animals are primarily active during daylight hours, typically resting or sleeping at night. - [Freshwater](https://www.snappit.app/explore/traits/freshwater): Freshwater habitats include non-saline aquatic environments such as rivers, lakes, ponds, and wetlands, vital for numerous species. - [Keystone Species](https://www.snappit.app/explore/traits/keystone-species): Describes a species whose presence and role have a disproportionately large effect on its environment. - [Miniature](https://www.snappit.app/explore/traits/miniature): Pertaining to species that are significantly smaller than typical or average for their kind. - [Pollinator](https://www.snappit.app/explore/traits/pollinator): Describes organisms that transfer pollen, enabling the fertilization and reproduction of plants. ## Collections - [Insects](https://www.snappit.app/explore/collections/insects) ## Safety **Danger:** 1/5 · Very low Always wash your hands after playing near water to stay clean and healthy. ## Frequently Asked Questions ### How to identify Stream Mayflies? Look for six legs, antennae, three body sections and the shape of the wings. Beetles have hardened front wings; flies have just one working pair. Tiny insects may need a close view before their group is clear. Insect Identifier: upload a photo and compare the visible details. ### What is Stream Mayflies's wingspan? 10-30 mm ### How big is Stream Mayflies? 5-20 mm ### How long does Stream Mayflies live? 30-365 days ### How fast can Stream Mayflies fly? 10 km/h ### What does Stream Mayflies eat? Nymphs graze on tiny plants and decaying bits, while adults astonishingly do not eat at all! ### Where is Stream Mayflies usually found? Freshwater streams ### How does Stream Mayflies hunt? Grazing ## More Insects - [Common Eastern Bumble Bee](https://www.snappit.app/explore/common-eastern-bumble-bee) (*Bombus impatiens*) - [Spotted Lanternfly](https://www.snappit.app/explore/spotted-lanternfly) (*Lycorma delicatula*) - [Brown-belted Bumble Bee](https://www.snappit.app/explore/brown-belted-bumble-bee) (*Bombus griseocollis*) - [Eastern Carpenter Bee](https://www.snappit.app/explore/eastern-carpenter-bee) (*Xylocopa virginica*) --- Source: [Stream Mayflies: Facts & Places to See — Snappit](https://www.snappit.app/explore/stream-mayflies)