BugWise

What do mayflies look like?

An example of a mayfly. Photo: M Bulbert © Australian Museum.

Mayfly. Illustration: A Howells © Australian Museum.

Size:

4 mm - 35 mm in length with an average wingspan of 15 mm across.

Body:

Widest at wing attachment (wide shoulders), abdomen long and column-like.

Body appears soft and fragile.

Antennae:

Very short, bristle-like or thread-like.

Eyes:

Large, covering most of the head, and are very close together or actually touch.

Mouthparts:

Reduced in adult.

Wings:

One or two pairs but usually two.

Hindwings much smaller than forewings.

Both wings are membranous, clear and have numerous cross-veins forming many cells.

At rest wings are held upright above abdomen often pressed together.

Limbs:

Six slender legs.

Abdomen tip:

Usually three tails (two cerci, one middle filament) rarely two with middle tail reduced or absent; all tails longer than body, thread-like and similar in size.

Where are mayflies found?

• Near water on vegetation, rocks or in the air.

What do mayflies do?

• They group together in large numbers to form mating swarms. The swarms are often over a particular object such as a rock, tree, or bridge. This object can be indicative of a particular species.
• When disturbed they fly away.
• Many hold their front legs out in front when perched.
• They are weak flapping fliers.
• Adult mayflies do not feed.
• Adults are short-lived, on average survive for 1-2 days, but can live for only minutes.
• They are active night and day. Some are attracted to light.

What looks similar?

• Stoneflies can be distinguished from Mayflies by their wings. Their wings are similar in size and folded around the body at rest. Stoneflies also never have more than two tails.
• Caddisflies can be distinguished from Mayflies by their wings, antennae and a lack of tails. Their wings are hairy, similar in size and held tent-like at rest. While their antennae tend to be more than half their body length.
• Alderflies and dobsonflies can be distinguished from Mayflies by a number of features. Their wings are similar in size and held tent-like at rest. They also have chewing mouthparts, long antennae and very short tails.
• Flies can be distinguished from Mayflies by their wings and a lack of tails. The forewings of flies have few cells, while their hindwings are replaced by a club-like structure called halteres.
• Male scale insects are occasionally confused as Mayflies. Wings of scale insects have few cells and their tails, if present, are never multi-segmented.