Ephemeroptera

may fly

Introduction

Mayflies. A small order of 2000+ species worldwide, 620+ species in North America, north of Mexico. The most ancient extant winged insects. Unique winged subimago, very short-lived adults. Paleoptera- Hemimetabolous.

Recognition

Nymphs- external wingpads present, unmodified chewing mouthparts, tarsi with one claw, abdomen usually ending in 3 caudal filaments (sometimes 2). Adults- 1 or 2 pair of non-folding wings, mouthparts vestigial, antennae bristlelike and inconspicuous, abdomen ending in 2 or 3 long filaments.

Life cycle

The eggs may hatch immediately (ovoviviparous) or remain dormant for many months. The nymphs grow through many instars (10-50). The last instar may molt while on the bottom, in midwater, on the surface, or above the water depending on the species. The first winged stage is a sexually immature subimago, or dun (sexually mature in females of a few species). The subimago soon molts to the imago (spinner). Males (sometimes females) swarm to attract mates. Mating takes place in the air, at least initially. The eggs are usually deposited upon the water and quickly separate, sink and adhere. The timing of emergence, swarming, and egg laying are all species specific, but mostly at dusk. Most temperate species are univoltine, many are multivoltine in warm waters, few are semivoltine. Many species are restricted to the summer season. A few species are parthenogenetic.

Trophic roles

The nymphs of most species are general collector-gatherers. Some species are filterers or scrapers and a few species are predatory, especially in large rivers. Adults do not feed.

Communities

Moderately complex in undisturbed streams of all sizes, with moderate numbers of species separated by habitat, season, or altitude. Springs, lakes, ponds, and temporary pools have few species, but often have large populations.

Economic importance

Important intermediate consumers in many systems, fish bait, majority of fishing fly patterns, water quality indicators, some nuisance emergences.

Zoogeography

A well studied and useful group. Short lived and fragile adults and specific habitat requirements of the nymphs limit their dispersal. Few species inhabit island situations. Species restricted to large river are often endangered.

Collecting

Nymphs make the best species list, as many adults are secretive. Nymphs are generally abundant and easily collected by routine benthic sampling, but must be handled with care. Many species are restricted to shoreline areas. Some species occur in the benthos for only a short time each summer. Active swimmers may avoid nets. Adults can be collecting while swarming by using long handled nets, or while resting on structures. Nocturnal species are often attracted to lights.

Rearing

Mature nymphs can frequently be reared if kept in half-submerged cages in the field, the adults (subimagoes and imagoes) must have room to stay away from the water as they easily drown. Collected subimagoes must be handled very carefully and kept alive in dry Styrofoam containers in a cool place until the final molt occurs. Eggs are usually fully developed in the mature nymph and can help associate females.

Preservation

Adults are normally collected and stored in 70% ethanol, they are best collected a few at a time directly into the final storage vials. A few pinned specimens are often useful as they retain their color better. Nymphs are best fixed in Khale's fluid and transferred to 70% ethanol after a few days. They too require delicate handling.

Taxonomy

Messy! Ephemeroptera is an ancient and decimated order of unpopular, fragile insects with many cases of convergent and parallel evolution. Their taxonomy has been dominated by evolutionary taxonomists, who have chosen not to use phylogenies for classification, but to arbitrarily delimit higher taxa based on their degree of differentiation. Early workers used adult characters, often unstable color characters. Modern workers often prefer to use nymphal characters. Many genera have their species partially named from adults and partially named from nymphs. Many synonyms are yet to be sorted out. Many species remain to be described. Many more higher taxa are needed to produce a natural (phylogenetic) classification. Relatively few faunal treatments available.

Montana Species list

Reference Update

  • Funk, D.H. and B.W. Sweeney. 1994. The larvae of eastern North American Eurylophella Tiensuu (Ephemeroptera: Ephemerellidae). Trans. Amer. Ent. Soc. 120:209-286.
  • McCafferty, W.P., R.S. Durfee and B.C. Kondratieff. 1993. Colorado mayflies (Ephemeroptera) - an annotated inventory. Southwest. Nat. 38:252-274.
  • Henry, B.C., Jr. 1993. A revision of Neochoroterpes (Ephemeroptera: Leptophlebiidae) new status. Trans. Amer. Ent. Soc. 119:317-333.
  • Bae, Y.J. and W.P. McCafferty. 1991. Phylogenetic systematics of the Potamanthidae (Ephemeroptera). Trans. Amer. Ent. Soc. 117:1-143.
  • McCafferty, W.P. 1991. Toward a phylogenetic classification of the Ephemeroptera (Insecta): A commentary on systematics. Ann. Ent. Soc. Amer. 84:343-360.
  • McCafferty, W.P. and R.D. Waltz. 1990. Revisionary synopsis of the Baetidae (Ephemeroptera) of North and Middle America. Trans. Amer. Ent. Soc. 116:769-799.
  • McCafferty, W.P. and Y.J. Bae. 1990. Anthopotamus, a new genus for North American species previously known as Potamanthus (Ehemeroptera: Potamanthidae). Ent. News 101:200-202.
  • Provonsha, A.V. 1990. A revision of the genus Caenis in North America. (Ephemeroptera: Caenidae). Trans. Amer. Ent. Soc. 116:801-884.
  • Campbell, I.C., ed. 1990. Mayflies and stoneflies life histories and biology. Kluwer Academic Publishers, Boston, 366pp.
  • Berner, L. and M.L. Pescador. 1988. The Mayflies of Florida, Revised Ed. University of Florida Press, Gainesville, 415pp.
  • Waltz, R.D. and W.P. McCafferty, 1987. Revision of the genus Cloeodes Traver (Ephemeroptera: Baetidae). Ann. Ent. Soc. Amer. 80:191-207.
  • Waltz, R.D. and W.P. McCafferty, 1987. New Genera of Baetidae for some Nearctic species previously included in Baetis. Ann. Ent. Soc. Amer. 80:667-670.
  • Waltz, R.D. and W.P. McCafferty, 1987. Systematics of Pseudocloeon, Acentrella, Baetiella, and Liebebiella, new genus (Ephemeroptera: Baetidae). J. New York Ent. Soc. 95:553-568.
  • Whiting, E.R. And D.M. Lehmkuhl. 1987. Raptoheptagenia cruentata, gen. nov. (Ephemeroptera: Heptageniidae ), new association of the larva previously thought to be Anepeorus with the adult of Heptagenia cruentata Wash. Can. Ent. 119:405-407.
  • Whiting, E.R. And D.M. Lehmkuhl. 1987. Acanthomola pubescens, A new genus and species of Heptageniidae (Ephemeroptera) from western Canada. Can. Ent. 119:409-417.
  • Soldan, T. 1986. A revision of the Caenidae with ocellar tubercles in the nymphal stage (Ephemeroptera). Acta Universitatis Carolinae, Ser. Biol., Praha. 1982-1984:289-362.
  • Landa, V. and T. Soldan. 1985. Phylogeny and higher classification of the order Ephemeroptera: A discussion from the comparative anatomical point of view. Ceskoslovenska Akad. Ved., Praha. 121pp.
  • Kondratieff, B.C. and J.R. Voshell, Jr. 1984. The North and Central American species of Isonychia (Ephemeroptera: Oligoneuriidae). Trans. Amer. Ent. Soc. 110:129-244.
  • Allen. R.K. 1984. A new classification of the subfamily Ephemerellinae and the description of a new genus. Pan-Pac. Ent. 60:245-247.

Other sites

Updated on 17 NOV 1995 D.L. Gustafson