THE INSECTLIBRARY FIELD GUIDES

MayflyIdentification, facts & practical guidance

Mayflies are insects in Ephemeroptera with aquatic young and short-lived winged adult stages.

Compiled by the InsectLibrary Team · Updated 2026-09-30 · Editorial policy

Identification and lookalikes

Hexagenia limbata - Giant Mayfly(c) Linda Jo Conn, some rights reserved (CC BY). https://creativecommons.org/licenses/by/4.0/ Source: https://www.inaturalist.org/observations/402829927

Stenacron interpunctatum - Stenacron interpunctatumContributed by tom murray; Additional contributions by v belov , Marci Hess

Adults commonly have two or three long tail filaments and hold the large forewings upright at rest. Compare with stoneflies and other stream insects using wing posture and body details.

Aquatic nymphs and emergence

Much of a mayfly’s life occurs underwater. Adults emerge to reproduce, sometimes in large numbers. The duration of the aquatic stage and emergence season depend on species and local conditions.

What to do next

Observe emergences from a safe shoreline and photograph the insect in place. Large numbers near lights can be temporary; they do not mean mayflies are breeding inside a building.

Mayfly: species profiles

Explore 387 species profiles covered by this guide, with recorded names and available photos.

Giant Mayfly

Hexagenia limbata

European Green Drake

Ephemera danica

Stenacron interpunctatum

Hexagenia bilineata

Drake Mackerel

Ephemera vulgata

Stenonema femoratum

Callibaetis ferrugineus

Isonychia bicolor

Callibaetis pictus

Maccaffertium terminatum

Blue-winged Olive

Serratella ignita

Maccaffertium modestum

Sources and further reading

mdc.mo.gov - mayfly larvaehttps://mdc.mo.gov/discover-nature/field-guide/mayfly-larvae

References support the subject discussed here; they do not certify every imported directory record. Regional sources describe their own locations. Read our source and correction policy.