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Hex Mayflies
Hexagenia limbata

The famous nocturnal Hex hatch of the Midwest (and a few other lucky locations) stirs to the surface mythically large brown trout that only touch streamers for the rest of the year.

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Mayfly Species Ecdyonurus simplicioides (Western Ginger Quill)

This is an important Western hatch.

Where & when

Time of year : Mid-July to late September

This is one of the most widely distributed of the former Heptagenia species in the West.

In 14 records from GBIF, adults of this species have been collected during June (50%), July (21%), August (14%), and May (14%).

In 8 records from GBIF, this species has been collected at elevations ranging from 4833 to 6270 ft, with an average (median) of 5066 ft.

Hatching behavior

The emergence is implied to be of some importance, but not much has been written about it in the books I've studied.

Egg-Laying behavior

Time of day: Evening, sometimes morning

The spinner fall is the most important activity of this species for the angler.

Physical description

Most physical descriptions on Troutnut are direct or slightly edited quotes from the original scientific sources describing or updating the species, although there may be errors in copying them to this website. Such descriptions aren't always definitive, because species often turn out to be more variable than the original describers observed. In some cases, only a single specimen was described! However, they are useful starting points.

Male Spinner

Described in Needham et al (1935) as Heptagenia simplicioides
Body length: 7-8 mm
Wing length: 8 mm

A pale yellowish species; genitalia of the simplicioides type (see fig. 96).

Head and thorax pale creamy to yellowish white. Clypeus slightly sprinkled with dark brown dots. Pinkish shading on pleura anterior to wing root and anterior to middle coxa. Legs pale whitish. Apex of fore tibia, basal fore tarsal joint, claws, distal joints and joinings of middle and hind legs deep smoky. Remaining joints of fore tarsus slightly smoky. Basal fore tarsal joint about 1/4 as long as the second. Basal joint of third tarsus apparently variable, as it is less than the second in specimens from Waterton Lakes, but slightly longer than second on those from Yakima, Wash. Wings hyaline; both longitudinal and cross veins pale. Basal costal cross veins almost invisible, very few in number. 11 to 12 cross veins beyond bulla, those in stigmatic area quite regularly spaced; these, and cross veins of apical portion of subcostal space, slightly coarser than others, which are very fine and faint.

Abdominal segments pale creamy to yellowish white; 2-6 semi-hyaline, 7-10 opaque, the latter distinctly more yellowish. On tergites, the tracheae are outlined in pale grey. Tails pale yellowish white; a few of the basal joinings are pale reddish, others not darker than tail joints. Penes quite similar to H. rodocki (now a synonym of E. simplicioides), but the median spines shorter and less twisted; no lateral spines near margin are noticeable.

Described as H. rodocki

Body length 8 mm, wing length 8 mm

Mesonotum pale reddish brown; semi-translucent brownish lateral patches on abdominal tergites and sternites; unique pair of long twisted spines in median portion of penes. Head pale reddish yellow; a small faint dark dot usually present on each side of median carina; eyes large, deep reddish purple (alcohol). Bases of antennae pale; filament smoky, tips pale. Thorax yellowish red to pale reddish brown; sutures very narrowly smoky, no other dark markings. Metanotum darker than other portions. Fore coxa and trochanter shaded faintly with purplish brown; fore leg pale reddish brown; femur usually darker brown at extreme base and apex; tibia blackish brown apically; tarsus smoky brown, distal joint and claw darker, joinings narrowly darker. Tibia slightly longer than femur; tarsus only slightly longer than tibia; basal joint of fore tarsus 1/4 to 1/5 of the second joint. Middle and hind legs pale yellowish, coxae and trochanters often pale reddish; distal tarsal joint, claws and tarsal joinings dark smoky brown. Basal joint of hind tarsus distinctly longer than second joint. All femora more or less marked at base, near median area and longitudinally between these points, with opaque whitish patches, which in transmitted light appear black. Wings hyaline, venation pale; costa, subcosta and radius pale yellowish brown apically, other longitudinal veins very pale yellow; cross veins whitish, almost invisible, especially in basal costal space; 4 or 5 veins before bulla, 12-16 beyond it, in costal area, the latter faintly yellow-brown.

Abdomen pale yellowish; segments 2-7 semi-hyaline; 8-10 opaque, deeper yellowish red; joinings subopaque, appear darker in some lights. Tergites 2-7 with semi-translucent lateral patches, brownish, widely rectangular in shape, occupying most of each side, leaving a pale median line and pale lateral areas; these arise from or near the posterior margin and are darkest here; on some tergites, each patch may be divided anteriorly into 2 or 3 dark streaks. On some specimens, these patches are not present, and are difficult to see even when present. Sternites 2-7 with elongated lateral patches much like those of the tergites. Genitalia most resembling H. simplicioides (now a synonym of E. simplicioides). Third joint of forceps longer than terminal joint, these two together almost as long as second joint. Penes with a rather wide median and a narrow apical lobe on each side; a pair of apical spines, one near apical margin, on each side; median basal area occupied by two very long and twisted spine-like processes, which seem to be capable of rotation near the middle, so that the upper half may extend laterally at right angles to lower portion, as flattened blade-like structures (see fig. 98). These spines are apparently unique among the species in our fauna. Tails whitish, unmarked.

Female wholly pale yellowish; a narrow purplish line behind the eye. Base of fore leg pale reddish brown, all claws and distal joint of fore tarsus purplish brown. This species, unique because of the peculiarly long and twisted median spines on the penes, seems to be allied to H. simplicioides (now a synonym of E. simplicioides), which lacks the darker abdominal markings, and to H. rubroventris (now a synonym of Ecdyonurus criddlei) in which the abdominal markings are wide median dorsal and ventral bands.

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