Fly-fishing
Guides
Callibaetis ferrugineus
Red Speckled Dun
Callibaetis ferrugineus is a small minnow mayfly in the family Baetidae, commonly known as the Red Speckled Dun. The species is distributed across northern and southwestern Canada, the western United States, and Alaska. As with all mayflies, it undergoes incomplete metamorphosis with aquatic nymphal stages and short-lived adult stages. The species includes two recognized subspecies: C. f. ferrugineus and C. f. hageni.
Callibaetis pictus
Speckled Dun
Callibaetis pictus is a small minnow mayfly in the family Baetidae, commonly known as the Speckled Dun. It is distributed across Central America and North America, including all of Mexico and the northern and southwestern United States. Like other mayflies, it has an aquatic nymphal stage lasting months to years, followed by a brief adult lifespan measured in hours to days. The species is part of the EPT index (Ephemeroptera, Plecoptera, Trichoptera) used to assess water quality in environmental monitoring.
Capniidae
small winter stoneflies, winter stoneflies
Capniidae, the small winter stoneflies, is one of the largest families in the order Plecoptera, comprising approximately 300 species distributed throughout the Holarctic region. Adults are active during winter months, often observed on snow-covered stream banks when most other insects are dormant. The family exhibits notable adaptations to cold environments, including antifreeze compounds and winglessness in some species, which has led to high endemism and restricted distributions. Their closest relatives are the rolled-winged stoneflies (Leuctridae).
Dicosmoecus
October Caddisflies
Dicosmoecus is a genus of caddisflies in the family Limnephilidae, commonly known as October Caddisflies. The genus contains approximately six described species distributed across western North America, from California and Oregon through British Columbia to the Rocky Mountains. Species such as D. gilvipes and D. atripes are among the most intensively studied North American caddisflies due to their large larval size, synchronous autumn emergence, and importance in freshwater ecosystem research and fly-fishing culture.
Drunella
Blue-winged Olives, Spiny Crawler Mayflies
Drunella is a genus of spiny crawler mayflies in the family Ephemerellidae, comprising at least 20 described species. These mayflies are aquatic insects with nymphs that inhabit stream environments and are significant components of freshwater food webs. Adults are important to fly fishermen, who commonly refer to them as "Blue-winged Olives" and imitate them with artificial flies. Some species, such as Drunella grandis (the green drake), are particularly valued as trout food sources.
Drunella coloradensis
Small Western Green Drake
Drunella coloradensis is a species of spiny crawler mayfly in the family Ephemerellidae, commonly known to anglers as the Small Western Green Drake. The species is found in freshwater streams across western North America, with a range extending from Alaska and northern Canada through the western United States to northern Mexico and Central America. Nymphs are known to alter their behavior in response to short-term pH reductions, becoming more active under acidic conditions. The species is of particular importance to fly fishermen, who imitate its various life stages with artificial flies.
Drunella doddsii
Western Green Drake
Drunella doddsii is a species of spiny crawler mayfly in the family Ephemerellidae, commonly known as the Western Green Drake. Originally described as Ephemerella doddsi by Needham in 1927, this species is significant to fly fishing communities in western North America. The species is part of the diverse Drunella genus, which includes other notable green drake species such as D. grandis.
Drunella flavilinea
Flav
Drunella flavilinea is a species of spiny crawler mayfly in the family Ephemerellidae. It is native to Central America and North America, with a range spanning southwestern Canada, the western United States, and northern Mexico. The species is known to fly fishermen by the common name "Flav" and is an important component of trout diets in western streams.
Drunella grandis
Western Green Drake, Green Drake, Spinner Green Drake
Drunella grandis is a species of spiny crawler mayfly in the family Ephemerellidae. It is commonly known as the Western Green Drake among fly fishermen, who highly value this species for its importance as a trout food source. The species is native to North America and has been documented with three recognized subspecies. Adults are notable for their large size and greenish coloration, making them a prominent feature of western North American streams.
Drunella spinifera
Western Slate Olive
Drunella spinifera is a species of spiny crawler mayfly in the family Ephemerellidae. It is found in southwestern and northern Canada, the western United States, and Alaska. The common name "Western Slate Olive" reflects its regional distribution and likely coloration. Like other members of the genus Drunella, it belongs to a group of mayflies commonly targeted by fly fishermen, though specific angling references for this species are limited.
Drunella tuberculata
spiny crawler mayfly
Drunella tuberculata is a species of spiny crawler mayfly in the family Ephemerellidae, described by Morgan in 1911. It is found in North America and is closely related to D. allegheniensis, from which it can be distinguished by specific morphological characters. The species is part of a group of mayflies important to fly fishermen, where nymphs and adults serve as significant food sources for trout and other sport fish.
Drunella walkeri
Small Blue-winged Olive
Drunella walkeri is a species of spiny crawler mayfly in the family Ephemerellidae, commonly known as the Small Blue-winged Olive among anglers. It is found in North America and is one of the mayfly species frequently imitated by fly fishermen. The species was first described by Eaton in 1884.
Ephemera guttulata
Eastern Green Drake, Shad Fly, Coffinfly
Ephemera guttulata, commonly known as the eastern green drake, is a burrowing mayfly species native to eastern North America. It is one of the largest mayfly species in the region and is highly significant to fly fishing, where its emergence events are eagerly anticipated. The species has a fully aquatic larval stage, followed by a winged subimago (dun) stage and a short-lived sexually mature adult (imago) stage. Its conservation status is G5 (secure) according to NatureServe.
Ephemera simulans
Brown Drake
Ephemera simulans is a burrowing mayfly species in the family Ephemeridae, commonly known as the Brown Drake. It is widely distributed across North America, particularly common in the Rocky Mountains, Midwest, and Great Lakes region. The species is economically significant in recreational fly fishing, where both nymph and adult stages are imitated with artificial flies. Nymphs inhabit sand and silt substrates of lakes and streams, emerging as adults primarily at night from mid-June to mid-July.
Ephemerella
Hendricksons, Sulphurs, Pale Duns
Ephemerella is a genus of spiny crawler mayflies comprising approximately 19 described species. Nymphs are characterized by their distinctive defensive posture, curling the abdomen upward in a scorpion-like manner when disturbed. The genus has a widespread distribution across North America and Europe, with species occupying diverse lotic freshwater habitats. Several species, including E. subvaria and E. ignita, have been subjects of detailed life history studies.
Ephemerella dorothea infrequens
Pale Morning Dun
Ephemerella dorothea infrequens is a subspecies of mayfly in the family Ephemerellidae, commonly known as the Pale Morning Dun. It is an aquatic insect whose nymphal stage inhabits freshwater environments. The species is recognized as an important food source for trout and is frequently imitated by fly fishers using artificial flies. It was described by McDunnough in 1924 and is accepted as a valid subspecies within the Ephemerella dorothea complex.
Ephemerella excrucians
Pale Morning Dun
Ephemerella excrucians, commonly known as the pale morning dun, is a species of spiny crawler mayfly in the family Ephemerellidae. It is distributed across all of Canada and the continental United States. The species is of particular interest to fly fishers due to its importance as a trout food source and its frequent use as a model for artificial flies.
Ephemerella tibialis
Little Western Dark Hendrickson
Ephemerella tibialis is a species of spiny crawler mayfly described by McDunnough in 1924. It belongs to the family Ephemerellidae, a group known for their distinctive spiny or tuberculate body ornamentation. The species is found in North America and is recognized among anglers by the common name Little Western Dark Hendrickson, indicating its importance as a model organism for fly-fishing.
Ephemerellidae
Spiny Crawler Mayflies
Ephemerellidae, commonly known as spiny crawler mayflies, is a family of mayflies (Ephemeroptera) comprising approximately 90 species across 8-14 genera. The family is distributed throughout North America and the UK, with additional records from Europe and Asia. Nymphs inhabit lotic-erosional environments including flowing streams of all sizes, lake shores, and beaches with wave action. They are primarily collector-gatherers and serve as important indicators of water quality due to their sensitivity to pollution.
Helicopsyche
Speckled Peter, Spiral Caddisflies
Helicopsyche is a genus of caddisflies (Trichoptera: Helicopsychidae) containing more than 230 species with highest diversity in tropical and sub-tropical regions. The genus is represented on all major faunal regions worldwide. Larvae construct distinctive helical, snail-shell-like cases from sand grains and silk. Adults are known to fly fishers as the 'Speckled Peter'. The genus was first described by Siebold in 1856.
Hexagenia atrocaudata
Lake Hex
Hexagenia atrocaudata is a burrowing mayfly species in the family Ephemeridae, known from North American lakes and rivers. As a member of the common burrower mayflies, it spends the vast majority of its life as an aquatic nymph in bottom sediments, emerging as a short-lived winged adult for reproduction. Adults lack functional mouthparts and do not feed. Mass synchronous emergences can occur, producing swarms that attract fish and anglers alike. The species serves as an important indicator of clean freshwater ecosystems and provides substantial food resources for aquatic and terrestrial predators.
Isonychia
Slate Drakes, Brushlegged Mayflies
Isonychia is a genus of mayflies comprising over 30 described species, commonly known as Slate Drakes or brushlegged mayflies. The genus is the sole member of the family Isonychiidae. Nymphs are notable for possessing raptorial forelegs adapted for predation, a trait uncommon among mayflies. Some species exhibit habitat generalist ecology while others are specialized to intermittent streams.
Nemouridae
spring stoneflies, brown stoneflies, forestflies, tiny winter blacks
Nemouridae is a family of stoneflies (Plecoptera) comprising over 700 described species, primarily distributed in the Holarctic region. Members are commonly known as spring stoneflies, brown stoneflies, or forestflies, and are important indicators of water quality in aquatic ecosystems. The family is characterized by small size, with adults typically measuring 5–8 millimeters in body length. Nemouridae occupy diverse flowing-water habitats, though they are most prevalent in smaller streams.
Pteronarcys californica
giant salmonfly, salmonfly, California giant stonefly
Pteronarcys californica, commonly called the giant salmonfly, is among the largest stoneflies in North America. The nymphal stage lasts 3–4 years in cold, well-oxygenated rivers, after which adults emerge in synchronized mass events during late spring to early summer. Adults are strikingly colored with bright orange abdomens, leg joints, and thorax segments, and carry egg masses resembling clusters of salmon roe. The species serves as a critical food source for salmonid fishes and is highly valued by fly anglers, making it both ecologically and culturally significant across western North American river systems.
Siphlonurus
primitive minnow mayflies, gray drakes
Siphlonurus is a genus of primitive minnow mayflies in the family Siphlonuridae, comprising more than 40 described species. Species inhabit temporary and intermittent ponds, with nymphal development occurring during spring months and adult emergence in late May to June. Adults are non-feeding and rely on energy reserves accumulated during the aquatic larval stage. The genus is notable among fly fishers for species such as Siphlonurus quebecensis (early brown quill), which is imitated with specialized fly patterns.
Siphlonurus alternatus
Northern Summer Mayfly
Siphlonurus alternatus is a primitive minnow mayfly with a Holarctic distribution spanning North America and Europe. The species is univoltine, overwintering as eggs and emerging as adults between May and August. Larvae inhabit deep pools in rivers, streams, and calcareous lakes, where they feed on fine particulate organic detritus. Adults emerge during daylight hours, with males forming swarms at dawn and dusk.
Siphlonurus columbianus
Columbian gray drake
Siphlonurus columbianus is a species of mayfly in the family Siphlonuridae, described by James Halliday McDunnough in 1925. It is native to the Nearctic region and is one of several Siphlonurus species known to fly fishermen as "gray drakes." Adults are medium-sized mayflies with distinctive body segmentation. Like other members of its genus, it has a two-winged adult stage and an aquatic nymphal stage. The species is occasionally referenced in angling literature, though detailed biological studies appear limited.
Siphlonurus quebecensis
early brown quill mayfly, gray drake
Siphlonurus quebecensis is a species of primitive minnow mayfly in the family Siphlonuridae. It occurs in North America and is known to anglers as the 'early brown quill' or 'gray drake,' a name reflected in fly-fishing patterns designed to imitate its adult form. The species is part of a group of mayflies whose aquatic nymphs and winged adults serve as important prey for trout and other sport fish.
Timpanoga
Timpanoga is a genus of spiny crawler mayflies in the family Ephemerellidae, established by Needham in 1927. The genus contains a single described species, Timpanoga hecuba, commonly known to fly fishermen as the great red quill. This species is significant in angling communities as a model for artificial fly patterns imitating adult and subimago (dun) forms.
Timpanoga hecuba
Great Red Quill
Timpanoga hecuba, commonly known as the Great Red Quill, is a species of mayfly in the family Ephemerellidae. This Nearctic species is significant in fly fishing, where its adult and subimago (dun) forms are imitated by artificial flies. The species was originally described as Ephemerella hecuba by Eaton in 1884 and later transferred to the genus Timpanoga.