Entomology (continued) Introduction
to Mayflies, Caddisflies, Stoneflies and Midges
Introduction To Mayflies
Mayflies are synonymous with flyfishing. Since the history of the sport, the two have been closely linked. The reasons why are obvious; no other insect is more available to the trout, and more noticeable to humans than the mayfly. Mayflies live almost their whole life under water. They are available to the fish as nymphs year round. When they finally emerge, they resemble small sailboats being blown around by their upright wings, lazily going where the wind and the current take them. This is the time of the hatch when mayflies are most vulnerable, and it is also the time which is treasured by flyfishermen the world over. Once they have left the water, the mayflies must go through one more change that will make them capable of reproduction. The insects then return to the water to breed and die, once again becoming food for the trout. The stages of life for a mayfly are egg, nymph, dun and spinner. Eggs can be deposited by the spinners in several ways; one is ovipositing, where eggs are dropped into the stream from above. Another form of egg laying takes place when the mature adult crawls onto aquatic vegetation and attaches their eggs to the plant. When the nymphs or larvae hatch, they crawl around the stream or lake bottom; it is usually a year before they are ready to hatch.
Hatching (the metamorphosis from the juvenile stage to the first flying stage) can also come about in different ways. The first is for the nymph to swim or float to the stream’s surface, where it will break open its nymphal shuck; a fully formed dun, or subimago, will crawl on to the water’s surface, dry its wings, and fly away. The second form of emergence is for the dun to crawl from the nymphal shuck onto the stream bottom, then swim to the surface as an adult fly.A few days after the duns (subimagos) have hatched, they shed once again, their body color changes, and their wings become clear; most importantly they become mature adults capable of reproduction. This reproductive stage is called the spinner or imago. The spinners will mate in huge swarms over the top of the water.
Once they have mated, they fall dead onto the water’s surface, spent winged, like hundreds of little crosses. Due to the sheer number of flies, a spinner fall can be one of the most productive, but often frustrating, times to fish
Identifying Mayflies
A nymph can be identified as a mayfly if it has all of the following characteristics:
1. Gills along its abdomen
2. A single claw at the end of its legs
3. One set of visible wing pads
4. 2 or 3 tails
Mayfly adults have the following characteristics:
1. 2 sets of wings that are upright at rest
2. 2 or 3 tails
3. A long, usually slender, body
Mayflies are synonymous with flyfishing. Since the history of the sport, the two have been closely linked. The reasons why are obvious; no other insect is more available to the trout, and more noticeable to humans than the mayfly. Mayflies live almost their whole life under water. They are available to the fish as nymphs year round. When they finally emerge, they resemble small sailboats being blown around by their upright wings, lazily going where the wind and the current take them. This is the time of the hatch when mayflies are most vulnerable, and it is also the time which is treasured by flyfishermen the world over. Once they have left the water, the mayflies must go through one more change that will make them capable of reproduction. The insects then return to the water to breed and die, once again becoming food for the trout. The stages of life for a mayfly are egg, nymph, dun and spinner. Eggs can be deposited by the spinners in several ways; one is ovipositing, where eggs are dropped into the stream from above. Another form of egg laying takes place when the mature adult crawls onto aquatic vegetation and attaches their eggs to the plant. When the nymphs or larvae hatch, they crawl around the stream or lake bottom; it is usually a year before they are ready to hatch.
Hatching (the metamorphosis from the juvenile stage to the first flying stage) can also come about in different ways. The first is for the nymph to swim or float to the stream’s surface, where it will break open its nymphal shuck; a fully formed dun, or subimago, will crawl on to the water’s surface, dry its wings, and fly away. The second form of emergence is for the dun to crawl from the nymphal shuck onto the stream bottom, then swim to the surface as an adult fly.A few days after the duns (subimagos) have hatched, they shed once again, their body color changes, and their wings become clear; most importantly they become mature adults capable of reproduction. This reproductive stage is called the spinner or imago. The spinners will mate in huge swarms over the top of the water.
Once they have mated, they fall dead onto the water’s surface, spent winged, like hundreds of little crosses. Due to the sheer number of flies, a spinner fall can be one of the most productive, but often frustrating, times to fish
Identifying Mayflies
A nymph can be identified as a mayfly if it has all of the following characteristics:
1. Gills along its abdomen
2. A single claw at the end of its legs
3. One set of visible wing pads
4. 2 or 3 tails
Mayfly adults have the following characteristics:
1. 2 sets of wings that are upright at rest
2. 2 or 3 tails
3. A long, usually slender, body
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Mayfly Nymph Burrower
Identifying Characteristics of Mayfly Nymph Burrowers Mayfly Nymph Clinger
Identifying Characteristics of Mayfly Nymph Clingers Mayfly Nymph Crawler Identifying Characteristics of Mayfly Nymph Crawlers Mayfly Nymph Swimmer
Identifying Characteristics of Mayfly Nymph Swimmers |
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Introduction to Caddis Flies
Because of the huge diversity of this order of insects (Trichoptera) the simplest form of identification is to group the insects by larval behavior. The following keys are broken down into 3 types of larval behavior, case builders, net spinners, and free living caddis. This key is more of an introduction to caddis rather than a functional key, with over 12,000 species it would be an impossible task to identify each and every one. Simple put, there are more caddis species than stonefly and mayfly species combined. Even at the Genera level there is 143. There is hope however, as a fly fisherman it is important to identify the insect and its basic characteristics. The following keys should help you do just that.
The Caddis fly has over 12,000 species in North America, more than all the mayfly and stonefly species combined. Even with all this diversity, they still take second place to mayflies in the east and stoneflies in the west. Their obscurity may be a direct result of their diversity; it is very difficult to catalog categories and imitate all of the caddis fly species. That all said, caddis flies are a very important food source for trout, and of equal importance to the fly fisher.
Caddis flies go through full metamorphosis, giving the fly fisherman three stages of life to imitate. The larval stage can be broken down by behavioral characteristics. Three basic behavioral characteristics are case building, net spinning and free living. The case building caddis use a myriad of material, both organic vegetation and rock or sand, to make their homes. Perhaps you have seen a small bunch of sticks or pebbles walk across the stream bottom. The free-living larva are voracious predators that feed on other small insects. Free living caddis live in riffles and fast currents, and because of their roaming life style, are available to trout year round. The net spinning caddis larva build stationary homes with catch nets. These nets are situated on the top of rocks in the main current to catch pieces of floating vegetation, and small organic debris, which the larva feed on.
The Pupa stage of the caddis fly is rarely seen by the fly fisherman, because of its fast transition to the adult stage. The pupa are fully encased inside a sealed cocoon on the stream bottom until they are ready to emerge. At the time of emergence, they break open the cocoon and swim very quickly to the water’s surface, where they explode into the air as a full formed adult. This rapid transition can cause trout to go wild. Trout may be seen leaping from the water as they chase the caddis flies from the stream bottom into the air.
The adult caddis flies mate soon after emergence in trees and bushes along the stream. They return to the water to deposit their eggs, usually at dusk. Caddis can lay their eggs in two different ways; one is called ovipositing, where the female flies over the water’s surface, releasing her eggs. Caddis may also dive under water or crawl down plants and rocks, depositing their eggs on the stream bottom. If you notice caddis on your waders while you are fishing some night, the green stuff on your boots the next morning will be caddis eggs.
Identifying Caddis Flies
Caddis fly larva have the following characteristics:
1. Six jointed legs
2. Grub or maggot like appearence
3. No tails
4. Anal hooks
5. May build a house with sticks, pebbles, leaves or other bottom debris
Caddis fly pupa have the following characteristics:
1. Long antennae, longer than their bodies
2. Legs that dangle freely
3. Short wing buds
Caddis fly adults have the following characteristics:
1. Tent shaped wings that fold over their back
2. Wings will have small hairs all over them
3. Long antennae
Because of the huge diversity of this order of insects (Trichoptera) the simplest form of identification is to group the insects by larval behavior. The following keys are broken down into 3 types of larval behavior, case builders, net spinners, and free living caddis. This key is more of an introduction to caddis rather than a functional key, with over 12,000 species it would be an impossible task to identify each and every one. Simple put, there are more caddis species than stonefly and mayfly species combined. Even at the Genera level there is 143. There is hope however, as a fly fisherman it is important to identify the insect and its basic characteristics. The following keys should help you do just that.
The Caddis fly has over 12,000 species in North America, more than all the mayfly and stonefly species combined. Even with all this diversity, they still take second place to mayflies in the east and stoneflies in the west. Their obscurity may be a direct result of their diversity; it is very difficult to catalog categories and imitate all of the caddis fly species. That all said, caddis flies are a very important food source for trout, and of equal importance to the fly fisher.
Caddis flies go through full metamorphosis, giving the fly fisherman three stages of life to imitate. The larval stage can be broken down by behavioral characteristics. Three basic behavioral characteristics are case building, net spinning and free living. The case building caddis use a myriad of material, both organic vegetation and rock or sand, to make their homes. Perhaps you have seen a small bunch of sticks or pebbles walk across the stream bottom. The free-living larva are voracious predators that feed on other small insects. Free living caddis live in riffles and fast currents, and because of their roaming life style, are available to trout year round. The net spinning caddis larva build stationary homes with catch nets. These nets are situated on the top of rocks in the main current to catch pieces of floating vegetation, and small organic debris, which the larva feed on.
The Pupa stage of the caddis fly is rarely seen by the fly fisherman, because of its fast transition to the adult stage. The pupa are fully encased inside a sealed cocoon on the stream bottom until they are ready to emerge. At the time of emergence, they break open the cocoon and swim very quickly to the water’s surface, where they explode into the air as a full formed adult. This rapid transition can cause trout to go wild. Trout may be seen leaping from the water as they chase the caddis flies from the stream bottom into the air.
The adult caddis flies mate soon after emergence in trees and bushes along the stream. They return to the water to deposit their eggs, usually at dusk. Caddis can lay their eggs in two different ways; one is called ovipositing, where the female flies over the water’s surface, releasing her eggs. Caddis may also dive under water or crawl down plants and rocks, depositing their eggs on the stream bottom. If you notice caddis on your waders while you are fishing some night, the green stuff on your boots the next morning will be caddis eggs.
Identifying Caddis Flies
Caddis fly larva have the following characteristics:
1. Six jointed legs
2. Grub or maggot like appearence
3. No tails
4. Anal hooks
5. May build a house with sticks, pebbles, leaves or other bottom debris
Caddis fly pupa have the following characteristics:
1. Long antennae, longer than their bodies
2. Legs that dangle freely
3. Short wing buds
Caddis fly adults have the following characteristics:
1. Tent shaped wings that fold over their back
2. Wings will have small hairs all over them
3. Long antennae
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Cased Caddis Fly Larva
Identifying Characteristics of Cased Caddis Fly Larva Free-Living Caddis Fly Larva Identifying Characteristics of Free-Living Caddis Fly Larva Net Spinning Caddis Fly Larva
Identifying Characteristics of Cased Net Spinning Caddis Fly Larva Net and Retreat Caddis Fly Pupa
Identifying Characteristics of Caddis Pupa 1) Long Antennae 2) Wing pads on either side of there thorax 3) Long dangeling legs 4) No Tails Caddis Fly Adult
Identifying Characteristics of Caddis Adult 1) Four wings with fine hairs 2) Wings form a tent shape over the body when at rest 3) Very long Antennae 4) No Tails |
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Introduction to Stone Flies
What is a stonefly? Adult stoneflies have 2 pairs of wings that are held flat over their bodies when they are not flying. The front pair of wings is usually a little longer than the back pair. Stoneflies also have 2 "tails" (cerci) on the tips of their abdomens. Young stoneflies are called nymphs or technically "naiads," and they are fully aquatic. Nymphs are flattened and, like the adults, have 2 tails on the tips of their abdomens, along with leafy gills at the bases of their legs. Both adult stoneflies and nymphs have chewing mouthparts, although the mouthparts on many adult stoneflies are non-functional. Like all insects, stoneflies have 6 legs, 3 body parts, and 2 antennae.
Size: Most stonefly adults and nymphs are ½" - 1" long.
Life Cycle: Stoneflies have incomplete metamorphosis: eggs are placed in masses on the water surface by adult stoneflies and hatch into nymphs. Nymphs may live underwater for a few years before moving to the water surface to molt into winged adults.
Ecology: Stonefly nymphs occur in fast moving streams where they are most commonly found clinging to the undersies of rocks. Many stonefly naiads are predators, feeding on other aquatic arthropods. Nymphs of other species eat plants and algae. Although stonefly nymphs were once very common in streams, they are very sensitive to pollution. These days, stonefly nymphs are only common in very clean water. Stonefly adults can not fly very well, and are usually found sitting on rocks near the streams where they emerged. Many stonefly adults do not feed, others feed on algae, pollen, or other plant parts. Stoneflies are a very important food source for fish and birds, and they are also eaten by spiders and predatory insects.
Common Stoneflies Families: As of Brigham et. al. 1982 the common families in our mountain stream are Capniidae - Allocapnia (shredders), Perlodidae - Isoperlacollectors, predators), and Perlidae - Acrineuria(predators). Many stonefly families areseasonally abundant. We have several common stonefly species in North Carolina and most are very similar in appearance and habits. Pictured below is a stonefly adult which has just molted. Insects are soft and unable to fly for a short time just after they molt, and are said to be in a "teneral" state.
Collecting and Photography: Adult stoneflies usually emerge from the water at very specific times of the year. Depending on the species, they are very common at certain times of the year, impossible to find at others. Many common species emerge in the late-spring and early summer, and they are most active at night. Look for them near fast-flowing streams and lakes. Stonefly nymphs, on the other hand, can be found at almost any time of the year in clean, clear streams. Stonefly nymphs, like all insect specimens, should be preserved in alcohol. Unlike some other aquatic insects, stonefly nymphs usually do not do well in home aquariums. Most stoneflies need running water with lots of oxygen - a condition that is difficult to maintain in an aquarium.
Stonefly Facts: Like many aquatic insects, stonefly nymphs need clean water to live. Because of this, scientists can tell if a stream is polluted or not based on whether stonefly naiads are present. Read more about using insects to determine water quality:
http://www.aces.edu/pubs/docs/A/ANR-1167/ANR-1167.pdf
What is a stonefly? Adult stoneflies have 2 pairs of wings that are held flat over their bodies when they are not flying. The front pair of wings is usually a little longer than the back pair. Stoneflies also have 2 "tails" (cerci) on the tips of their abdomens. Young stoneflies are called nymphs or technically "naiads," and they are fully aquatic. Nymphs are flattened and, like the adults, have 2 tails on the tips of their abdomens, along with leafy gills at the bases of their legs. Both adult stoneflies and nymphs have chewing mouthparts, although the mouthparts on many adult stoneflies are non-functional. Like all insects, stoneflies have 6 legs, 3 body parts, and 2 antennae.
Size: Most stonefly adults and nymphs are ½" - 1" long.
Life Cycle: Stoneflies have incomplete metamorphosis: eggs are placed in masses on the water surface by adult stoneflies and hatch into nymphs. Nymphs may live underwater for a few years before moving to the water surface to molt into winged adults.
Ecology: Stonefly nymphs occur in fast moving streams where they are most commonly found clinging to the undersies of rocks. Many stonefly naiads are predators, feeding on other aquatic arthropods. Nymphs of other species eat plants and algae. Although stonefly nymphs were once very common in streams, they are very sensitive to pollution. These days, stonefly nymphs are only common in very clean water. Stonefly adults can not fly very well, and are usually found sitting on rocks near the streams where they emerged. Many stonefly adults do not feed, others feed on algae, pollen, or other plant parts. Stoneflies are a very important food source for fish and birds, and they are also eaten by spiders and predatory insects.
Common Stoneflies Families: As of Brigham et. al. 1982 the common families in our mountain stream are Capniidae - Allocapnia (shredders), Perlodidae - Isoperlacollectors, predators), and Perlidae - Acrineuria(predators). Many stonefly families areseasonally abundant. We have several common stonefly species in North Carolina and most are very similar in appearance and habits. Pictured below is a stonefly adult which has just molted. Insects are soft and unable to fly for a short time just after they molt, and are said to be in a "teneral" state.
Collecting and Photography: Adult stoneflies usually emerge from the water at very specific times of the year. Depending on the species, they are very common at certain times of the year, impossible to find at others. Many common species emerge in the late-spring and early summer, and they are most active at night. Look for them near fast-flowing streams and lakes. Stonefly nymphs, on the other hand, can be found at almost any time of the year in clean, clear streams. Stonefly nymphs, like all insect specimens, should be preserved in alcohol. Unlike some other aquatic insects, stonefly nymphs usually do not do well in home aquariums. Most stoneflies need running water with lots of oxygen - a condition that is difficult to maintain in an aquarium.
Stonefly Facts: Like many aquatic insects, stonefly nymphs need clean water to live. Because of this, scientists can tell if a stream is polluted or not based on whether stonefly naiads are present. Read more about using insects to determine water quality:
http://www.aces.edu/pubs/docs/A/ANR-1167/ANR-1167.pdf
Stonefly Nymph (B. Newton, 2004)
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Stonefly (B. Newton, 2004)
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Stonefly Nymph
Identifying Characteristics of Stonefly Nymphs 1) Antennae pair 2) Multiple wing pads 3) Slender, segmented abdomen 4) 2 Tails Stonefly Adult
Identifying Characteristics of Stonefly Adult 1) Antennae pair 2) Wings form a flat shape over the body when at rest 3) Long, slender, segmented abdomen 4) 2 Tails |
Stonefly Nymph (B. Newton, 2004)
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Teneral stonefly (B. Newton, 2002)
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Introduction to Midges
Since it would be impossible to show all 5,000+ species of aquatic Diptera here, given are three examples of diverse, common midges. These examples share traits that are common in all aquatic Diptera. The three families choose span a large range in size and shape, from the very small Simuliidae (black fly) to the large Tipulidae (crane fly). The most common of all aquatic midges is the Chironomidae having 175+ genera and 1000+ species.
When a fishermen uses the word, midge, they are usually referring to any very small aquatic or terrestrial insect. On the other hand, when entomologists refer to a midge, they are speaking of Diptera, the order of true flies. Diptera means 2 wings, and encompasses all common flies, such as a housefly. This is one of the larger orders of insects; there are over 16,000+ species with 5,000 + having aquatic larval stages (that’s a lot of Latin). Luckily their diminutive size and their common characteristics make them easy to imitate
What midges lack in size, they make up for in quantity. Think of it this way – the largest mammal on this planet; whales, feed on the smallest organism; plankton.
Why? Because plankton are readily available, reproduce quickly and are numerous in quantity (high biomass). The lower you are on the food chain, the smaller your size, the faster you reproduce, the larger your quantity. Midges might not seem to be a big meal for a trout, but their availability and high quantities make them a food source that we can not overlook.
Midges go through complete metamorphosis, giving the fisherman three chances to imitate them: the larva, pupa, and adult stages. Because some midges have fast reproduction and are multi-brooding, these three stages are available to trout year round. You can find midges on warm days in the dead of winter on most trout waters.
Midges have gotten a bad rap over the years. Commonly called the fisherman’s curse, their small size has made them difficult to fish. Today’s technology, small hooks and light tippet, makes it easy and productive to fish the midge
Identifying Midges
A Midge larva has all of the following characteristics:
1. No segmented legs
2. Prolegs usually on abdomen and thorax
3. Maggot or worm like body
4. Head that may retract into body
Midge adults have the following characteristics:
1. Wings that lie flat over the body at rest
2. No tails
3. Short antennae no longer than the length of the body
Since it would be impossible to show all 5,000+ species of aquatic Diptera here, given are three examples of diverse, common midges. These examples share traits that are common in all aquatic Diptera. The three families choose span a large range in size and shape, from the very small Simuliidae (black fly) to the large Tipulidae (crane fly). The most common of all aquatic midges is the Chironomidae having 175+ genera and 1000+ species.
When a fishermen uses the word, midge, they are usually referring to any very small aquatic or terrestrial insect. On the other hand, when entomologists refer to a midge, they are speaking of Diptera, the order of true flies. Diptera means 2 wings, and encompasses all common flies, such as a housefly. This is one of the larger orders of insects; there are over 16,000+ species with 5,000 + having aquatic larval stages (that’s a lot of Latin). Luckily their diminutive size and their common characteristics make them easy to imitate
What midges lack in size, they make up for in quantity. Think of it this way – the largest mammal on this planet; whales, feed on the smallest organism; plankton.
Why? Because plankton are readily available, reproduce quickly and are numerous in quantity (high biomass). The lower you are on the food chain, the smaller your size, the faster you reproduce, the larger your quantity. Midges might not seem to be a big meal for a trout, but their availability and high quantities make them a food source that we can not overlook.
Midges go through complete metamorphosis, giving the fisherman three chances to imitate them: the larva, pupa, and adult stages. Because some midges have fast reproduction and are multi-brooding, these three stages are available to trout year round. You can find midges on warm days in the dead of winter on most trout waters.
Midges have gotten a bad rap over the years. Commonly called the fisherman’s curse, their small size has made them difficult to fish. Today’s technology, small hooks and light tippet, makes it easy and productive to fish the midge
Identifying Midges
A Midge larva has all of the following characteristics:
1. No segmented legs
2. Prolegs usually on abdomen and thorax
3. Maggot or worm like body
4. Head that may retract into body
Midge adults have the following characteristics:
1. Wings that lie flat over the body at rest
2. No tails
3. Short antennae no longer than the length of the body
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Black Fly
Identifying Characteristics of the Black Fly Larvae 1) Size range 1/8″ to 5/16″ 2) Swollen abdomen 3) Fanlike mouth brushes 4) Larva are attached by the end of their abdomens to the top of rocks Pupa 1) High branched spiracular gills on head 2) Can be found in slipper-shaped cases on rocks and vegetation Adult 1) Wings are broad 2) Thorax has strong arch 3) Antennae are short Crane Fly
Identifying Characteristics of the Crane Fly Larvae 1) Size range 3/8″ to 1″ 2) Some have retractable heads 3) Body has peglike appearance Pupa 1) Aquatic pupa are rare 2) Straight legs that extend beyond developing wings 3) Aquatic pupa will have respiratory horns Adult 1) Large mosquito like flies 2) Very long legs Midge Fly
Identifying Characteristics of the Midge Larva 1) Size range from 1/16″ to 3/4″ 2) Long slender worm like body 3) Distinct head 4) Has a pair of prothoracic prolegs and pair of terminal prolegs 5) Terminal segment has short tufts of hair Pupa 1) Most species live within cocoon attached to rocks or vegetation 2) Some are free swimming 3) Defined wing pads Adult 1) Two wings 2) Antennae are generally longer than the head and have hairs 3) Wings are delta shaped |
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Note: The Seth Green Trout Unlimited Chapter was gracious to allow us to use much of their entomology web pages. A majority of the illustrations you will see on these pages were drawn by Rick Harrington. He is a professional illustrator. If you wish to use the illustrations for any reason you must ask permission first. The contact information for Rick Harrington is 716-346-0772. All of the Illustrations found here are original or used with permission. The Izaak Walton League of America has graciously allowed the use their images from their Stream Study website. Their web site contains a good set of macroinvertabrate keys. Ken Manual is considered our Chapter entomologist.
Note: Stonefly information and photos courtesy of University of kentucky Entomology Department
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Rocky River Trout Unlimited - 2013
Note: Stonefly information and photos courtesy of University of kentucky Entomology Department
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Rocky River Trout Unlimited - 2013