Mayflies

Benthic Macroinvertebrates

Sensitive Benthos

Moderately Tolerant Benthos

Pollution Tolerant Benthos

Mayfly adult

Metamorphosis:

incomplete (see our life cycle page for more information)

Nymphs:

three distinct cerci (tails), occasionally two; cerci may be fuzzy or thread-like, but never paddle or fan-like; color varies from green, brown, gray, but usually black; total length up to 1 inch.

Reproduction:

female deposits eggs on top of water where they drift to the bottom; some species crawl under water and attach eggs to submerged objects.

Adults:

resemble nymphs, but usually possess two pair of long, lacy wings folded upright; adults usually have only two cerci.

Food:

consists of small plant and animal debris, such as algae, diatoms, and plankton; preyed upon by fish and play an important role in the food chain.

Mayfly nymph (Epeorus)

Scientific Name:

Class: Insecta
Order: Ephemeroptera

Indicator Role:

mayflies display a varied tolerance to pollution, but are generally considered cleaner water benthos.

Information Source:

McDonald, B., W. Borden, J. Lathrop.1990. Citizen Stream Monitoring: A Manual for Illinois. Illinois Department of Energy and Natural Resources, ILENR/RE-WR-90/18. Springfield, Illinois.

Burrowing Mayfly