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Mayfly Species Diphetor hageni (Little Blue-Winged Olive)

This is one of the most important species of the Baetidae family. Previously known as Baetis parvus in the West and its synonym (Synonym: A former name of a taxon, usually a species. Entomologists frequently discover that two insects originally described as different species are one in the same, and they drop one of the names. The dropped name is said to be a synonym of the remaining name. These changes take a while to trickle into the common knowledge of anglers; for example, Baetis vagans is now a synonym of Baetis tricaudatus.) Baetis devinctus in the East, it is distributed across the country but most of its fame comes from excellent hatches in the West. Prior to all the species being combined with Baetis tricaudatus, most angling literature considered it the most populous and widespread western species of the Baetidae family.

Dorsal (Dorsal: Top.) abdominal markings on the nymphs used to differentiate the species in these older works have since proved unreliable. The easiest way to tell them apart from B. tricaudatus is their lack of gills on the first abdominal segment. Telling adults apart is equally tough. Duns of D. hageni are typically a little smaller, but their bodies can also be olive, brownish olive and even two toned with thoraxes a shade of brown or tan with paler olivacious abdomens.

Diphetor hageni has two former names used in angling literature, Baetis parvus in the West and Baetis divinctus in the East.
  

Where & When


Regions: East, Midwest, West

Time Of Year (?): April and May, then another brood in September and October; sometimes another intermediate brood

Preferred Waters: Fertile streams


Hatching Behavior


The nymphs and duns are both important during this hatch.

Spinner Behavior


Fred Arbona in Mayflies, the Angler, and the Trout describes peculiar spinner behavior in this species:

Spinners gather in the mornings or evenings, and their tight swarms can be observed over the banks of the stream. After mating, the spinners suddenly vanish and reappear spent (Spent: The wing position of many aquatic insects when they fall on the water after mating. The wings of both sides lay flat on the water. The word may be used to describe insects with their wings in that position, as well as the position itself.) on the water.

Nymph Biology


These nymphs are very versatile: cold or warm water, slow or fast water, spring creeks and freestone streams.

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