Editing Mayfly (section)

=== Nymph ===

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| image1 = Mayfly nymph dorsal view wing buds paired gills.JPG
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| image2 = Leptophlebia.marginata.subimago.jpg
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| image3 = Mayfly instar.jpg
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| image4 = Eendagsvlieg (257301115).jpeg
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| footer = {{font|size=100%|font=Sans-serif|text=Top left: Mayfly nymph, dorsal view, showing the paired gills and three projections on the abdomen; wing buds are visible on the thorax. Top right: Subimago of ''[[Leptophlebia marginata]]''. Middle: Nymph of the mayfly ''[[Cloeon dipterum]]'', showing seven pairs of [[gill]]s along the sides of the abdomen. Bottom: Lateral view of mayfly [[Insect wing|wing]] translucent [[Iridescence#Examples|iridescence]].}}
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Immature mayflies are [[aquatic insect|aquatic]] and are referred to as nymphs or naiads. In contrast to their short lives as adults, they may live for several years in the water. They have an elongated, cylindrical or somewhat flattened body that passes through a number of [[instar]]s (stages), moulting and increasing in size each time. When ready to emerge from the water, nymphs vary in length, depending on species, from {{convert|3|to|30|mm|2|abbr=on}}.<ref name=McCafferty1983/> The [[insect morphology#Head|head]] has a tough outer covering of [[sclerotin]], often with various hard ridges and projections; it points either forwards or downwards, with the mouth at the front. There are two large [[arthropod eye|compound eyes]], three [[ocelli]] (simple eyes) and a pair of [[antenna (biology)|antennae]] of variable lengths, set between or in front of the eyes. The mouthparts are designed for chewing and consist of a flap-like [[labrum (arthropod mouthpart)|labrum]], a pair of strong [[mandible (insect mouthpart)|mandibles]], a pair of [[maxilla (arthropod mouthpart)|maxillae]], a membranous [[Insect mouthparts#Hypopharynx|hypopharynx]] and a [[labium (insect)|labium]].<ref name=Dominguez/>

The [[Insect morphology#Thorax|thorax]] consists of three segments – the hindmost two, the [[mesothorax]] and [[metathorax]], being fused. Each segment bears a pair of legs which usually terminate in a single claw. The legs are robust and often clad in bristles, hairs or spines. Wing pads develop on the mesothorax, and in some species, hindwing pads develop on the metathorax.<ref name=Dominguez/>

The [[Insect morphology#Abdomen|abdomen]] consists of ten segments, some of which may be obscured by a large pair of [[operculum (animal)|operculate]] gills, a thoracic shield (expanded part of the [[prothorax]]) or the developing wing pads. In most [[taxa]] up to seven pairs of [[gill]]s arise from the top or sides of the abdomen, but in some species they are under the abdomen, and in a very few species the gills are instead located on the [[arthropod leg|coxae]] of the legs, or the bases of the maxillae. The abdomen terminates in slender thread-like projections, consisting of a pair of [[Cercus|cerci]], with or without a third central [[caudal filament]].<!--<ref>Imms, A. D., rev. Richards, O. W. & Davies, R. G. (1970) ''A General Textbook of Entomology'' 9th Ed. Methuen 886 pp.</ref>{{Page needed}}--><ref name=Dominguez>{{cite book |last=Domínguez |first=Eduardo |title=Ephemeroptera de América Del Sur |url=https://books.google.com/books?id=dwaJWle8OfkC&pg=PA17 |year=2006 |publisher=[[Pensoft Publishers]] |isbn=978-954-642-259-0 |pages=17–24 }}</ref>