AddThis Social Bookmark Button

Mayfly, Shadfly, May flies, Ephemerida, Ephemerids

Mayflies, or Shadflies, are known by their habit of swarming around lights during summer. They are frequently found near water where they breed. At times, they appear in enormous numbers.

Structurally speaking, the adult insects are very interesting creatures. They are distinguished from other insects by their short antennae, extremely large front wings compared with very small hind wings, atrophied mouth-parts, and long, slender filaments, two or three in number, at the end of the abdomen.

Mayfly larvae are active creatures that breathe by means of tracheal gills. They feed mainly on vegetable matter or algae. Larvae may be found under stones in running streams or swimming among water plants in calm water. They can also be found at the bottom, more or less covered with slime and mud. Some forms burrow into the sand banks of rivers.
Mayfly, Shadfly, Ephemerida
Mayfly, Shadfly, Ephemerida
The mayfly pupa or nymph is active and feeds as well. It has small wing pads, and when ready to transform, it floats upon the water. Soon after this the nymph's back splits open, and the winged insect emerges. This emergence is extremely rapid, and the insect flies away almost immediately after the skin cracks.

There's a second molt after the nymph becomes fly. The mayfly continues on a journey to shore in a condition called the sub-imago, or a pre-adult stage. It's skin splits again and the true-imago or adult emerges. Sub-imago skin shedding has even been observed while the insect is in midair flight.
Mayfly, Shadfly, Ephemerida
Mayfly, Shadfly, Ephemerida
cicada, dog day, harvestfly, Tibicen pruinosa
Mayfly, Shadfly, Ephemerida
The adult stage of a mayfly's life is short. In fact, mayflies were named after the Ephemerides of Greek mythology, creatures which lived only one day. The English word ephemeral is derived from the same Greek root. Despite the name, mayflies typically live more than a day. Where the air isn't overly dry, mayflies can live for several days, though they generally die within three or four. Adult mouthparts and alimentary canal aren't designed for the chewing and digestion of food, so mayflies don't eat during their short life.

Males can be distinguished from females because only their hind legs are atrophied where in most females all legs are atrophied. While at rest, mayflies hold their front legs close together, extended straight in front of their head. At the same time their anal bristles are held slanting upwards. As a rule, mayflies remain calm during the day, limiting their flight to the cooler hours of sunlight or extending it later in the evening, just after sunset. Where there is a strong artificial light, they will fly until late in the night. The numbers in which these creatures swarm can be huge. In some areas, their bodies can accumulate like snowdrifts.
Mayfly, Shadfly, Ephemerida
Mayfly, Shadfly, Ephemerida
Mayfly, Shadfly, Ephemerida
Mayfly, Shadfly, Ephemerida
Mayflies generally mate in flight, with the male underneath. Most mayflies lay their eggs in fresh water, but at least one species lays them in brackish water. Females of some species discharge the contents of their ovaries in the form of a pair of egg-clusters. Upon reaching water, the clusters rapidly disintegrate, and the eggs sink into the streambed. Other species drop their eggs gradually, a few at a time. In that case, the female either lands on the surface of the water at intervals to wash off the eggs that have issued, or she creeps down into the water, enclosed within a film of air, to lay her eggs underneath rocks. If the eggs are laid underwater, the female attempts to float to the surface and fly away, or she may drown.

After the eggs hatch, mayfly larvae eat vegetation growing on rocks and stems of large water plants. Some are predaceous, and eat other small creatures. The larvae, or nymphs, shed their skins several times during the first few days of life. The majority of mayfly life is spent in the larval state, lasting from one to three years. In this time frame they molt up to twenty times.

Mayfly nymphs and adults are considered important as food for freshwater game fish, such as bass, crappie, catfish and perch. Their value as fish food far outweighs the temporary inconvenience of their swarming around backyard lights. Freshwater fish are so well acquainted with mayflies as food that imitation mayflies are popular sport fishing bait. Flies known as duns, drakes and spinners are all imitations of Ephemerids.
Mayfly, Shadfly, Ephemerida
Mayfly, Shadfly, Ephemerida
Mayflies have an interesting lifespan. How many critters do you know of that never eat as adults? Some warm summer evening when you're near a light by a body of water, keep an eye out for these fascinating little insects.


Andy Williams / CritterZone.com
The mayfly, shadfly, Ephemerida pictures on this page are available for commercial stock photography license. All text and photos that appear on this webpage are copyrighted and may not be copied or used in any way without permission from CritterZone.

CritterZone does not specifically endorse our advertisers, or their methods. We cannot control the ads that run on our articles. CritterZone advocates humane and respectful treatment of all creatures.


Save this page:

AddThis Social Bookmark Button