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Caddisfly Family Hydropsychidae

Mayflies

Caddisflies

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Taxonomic Navigation -?-

Kingdom Animalia (Animals)

» Phylum Arthropoda (Arthropods)

» Class Insecta (Insects)

» Order Trichoptera (Caddisflies)

» Family Hydropsychidae

Genus in Hydropsychidae
CeratopsycheSpotted Sedges	1	18
CheumatopsycheLittle Sister Sedges	5	28
HydropsycheSpotted Sedges	4	17
MacrostemumGlossy Wing Sedges	0	0
Potamyia	0	0

5 genera aren't included.

Pictures Below ↓

This the most important caddisfly family for fly anglers. They are extremely abundant in trout streams and their life cycle specifics make them very vulnerable to the trout.

Hydropsyche is the best-known genus, but it is probably now the least important of the big three: Hydropsyche, Cheumatopsyche, and Ceratopsyche. All of the most important Hydropsyche species were recently reclassified into Ceratopsyche.

Two species of note from the other genera are Potamyia flava, a relatively unimportant Southern species, and Macrostemum zebratum, the important species commonly known as the "Zebra Caddis."

Hatching Behavior

Before emerging, Hydropsychidae pupae drift along the bottom or just under the surface for an unusually long time, from a few minutes to a few hours. They then take an unusualy long time struggling out through the film. Both of these tendencies make them more ideal for the angler.

Egg-Laying Behavior

Gary LaFontaine writes in Caddisflies that Hydropsychidae females dive to lay their eggs on the river bottom. When they're done, instead of swimming back to the surface quickly, they dead-drift (Dead-drift: The manner in which a fly drifts on the water when not moving by itself or by the influence of a line. Trout often prefer dead-drifting prey and imitating the dead-drift in tricky currents is a major challenge of fly fishing.) and float up. This makes them exceptionally vulnerable to trout.

Swisher and Richards in Selective Trout say that some species oviposit by flying low over the surface and dipping their abdomens slightly into the water repeatedly lay eggs. I'm inclined to believe Swisher and Richards about the variation, and to assume that the behavior LaFontaine described is by far the more common of the two.

Larva & Pupa Biology

Diet: Microorganisms filtered by their nets

Current Speed: Medium to fast

Shelter Type: Nets instead of cases; may build shelters near nets

Hydropsychidae is the main family of net-spinning caddisflies. Instead of building cases to live in, they build small silk nets (usually between 0.5cm and 2cm across) over crevices in rocks and logs. The current brings their microscopic prey into these traps. One larva may build and tend to more than one net.

Many larvae of Hydropsyche and Ceratopsyche (and perhaps the others, though I have not

confirmed it) secrete a white line of silk, anchored to a rock on one end. They use it to rappel between rocks in the current, just as spiders or inchworms may use their silk to move around a tree. LaFontaine popularized the trick of whitening the last foot and a half of one's leader to imitate this anchor line, noting that it improved his success and made the larvae "almost as worthwhile as the pupae and adults."

On page 231 of Caddisflies, Lafontaine presents a very interesting chart relating the abundance and net mesh size of each Hydropsychidae genus to different habitat factors like river size and water temperature. Rather than try to summarize it here I will recommend that you buy the book.

Hydropsychidae Fly Fishing Tips

Because they are so common, imitations of this family perform very well as searching patterns (Searching pattern: Any artificial fly pattern used when trout that aren't feeding selectively on anything in particular. A searching pattern may be an attractor or an imitation of something specific that the fish might favor even though it's not currently hatching.). Most of the fashionable "Czech Nymphs" imitate Hydropsychidae larvae, as do Cinnamon Caddis dry flies, which perform very well according to a 1998 study in the British Medical Journal, paraphrased again in that journal and quoted here:

Many doctors fish for trout, but there have been endless arguments over the best choice of fly. To extend evidence based practice from their professional into their leisure hours (where it might conceivably be more useful) Britton et al ( p 1678) carried out a randomised trial of five different dry flies (artificial floating flies) on the River Kennet in Berkshire. Before the trial the investigators had most confidence in the Grey Wulff and least in the Cinnamon Sedge. In the trial the Cinnamon Sedge caught the most trout and also seemed to be significantly favoured by brown as opposed to rainbow trout. These findings are of biological as well as practical importance, but the trial was small and the authors press the urgent need for much more research.

Clearly more research is necessary to settle the issue convincingly. As the authors of the study point out,

None of the investigators has any intention of taking the slightest notice of the results of this study.

I vow to fish as much as possible until the question of which dry fly is best has been firmly resolved to the agreement of all.

Pictures of 19 Caddisfly Specimens in the Family Hydropsychidae:

Specimen Page:12 3

Cheumatopsyche (Little Sister Sedges) Caddisfly Pupa

View 10 PicturesThis is the first fully formed caddis pupa (technically, a pharate adult (Pharate adult: Caddisflies are considered to be pupae during their transformation from larva into adult. This transformation is complete before they're ready to emerge. The emerging insect we imitate with the "pupa" patterns we tie is technically called a pharate adult. It is a fully-formed adult caddisfly with one extra layer of exoskeleton surrounding it and restricting its wings.)) that I've collected and photographed alive and healthy. I'll put a video of this specimen online soon, too.

Collected April 14, 2007 from Cayuta Creek in New York
Added to Troutnut.com by Troutnut on April 22, 2007

Ceratopsyche (Spotted Sedges) Caddisfly Adult

View 18 PicturesThese big caddisflies were tempting trout as they wriggled out of their shucks (

View Full Size

Here's an underwater view of the pupal shucks of several already-emerged Brachycentrus numerosus caddisflies.

Shuck: The shed exoskeleton left over when an insect molts into its next stage or instar. Most often it describes the last nymphal or pupal skin exited during emergence into a winged adult.), while others skated across the water at a medium pace, probably egg-laying.

Collected May 15, 2007 from the West Branch of the Delaware River in New York
Added to Troutnut.com by Troutnut on May 18, 2007

Female Hydropsyche (Spotted Sedges) Caddisfly Adult

View 4 Pictures

Collected May 16, 2004 from unknown in Wisconsin
Added to Troutnut.com by Troutnut on January 25, 2006

Specimen Page:12 3

1 Streamside Picture of Hydropsychidae Caddisflies:

View Full Size and Comment (2X larger)

I saw something strange flying around near the streambank, fluttering on and off the water's surface, so I went to check it out. I didn't recognize the wing profile in flight, and it's no surprise! These two caddisflies were joined mating, and they were very reluctant to let go.

In this picture: Caddisfly Family Hydropsychidae.

StateNew York

LocationNeversink River

Date TakenMay 20, 2007

Date AddedJun 5, 2007

AuthorTroutnut

CameraPENTAX Optio WPi

Recent Discussions of Hydropsychidae

What flies to imitate 12 Replies »

Posted by Goose on Sep 19, 2006 in the genus Ceratopsyche

Last reply on Mar 21, 2010 by Martinlf

Jason: What species', in common angler language, are represented in this genus? I'm trying to determine which ones I should spend my time on imitating them. Are they October Caddis, Grannom Caddis, etc. Are those afore mentioned sedges? I would like to know the names so I can tie them the correct size and colors. Just trying to learn. Thanks

Reply Zebra Caddis 1 Reply »

Posted by Lastchance on Aug 4, 2008 in the species Macrostemum zebratum

Last reply on Aug 4, 2008 by Taxon

Is there a photo of one? I've never heard of them or perhaps I know them by a different name.

Your Thoughts On Hydropsychidae:

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Jargon Defined:

Abdomens: The rear and usually the longest (ten-segmented in mayflies) portion of an insect's body, to which the tails are attached.

Dead-drift: The manner in which a fly drifts on the water when not moving by itself or by the influence of a line. Trout often prefer dead-drifting prey and imitating the dead-drift in tricky currents is a major challenge of fly fishing.

Larva: Many classes of aquatic insects, such as caddisflies, midges, craneflies, dobsonflies, alderflies, and many more, are known as "larvae" rather than "nymphs" in their juvenile stages. They have mostly soft bodies rather than hard exoskeletons. These insects also advance through a "pupa" stage before reaching adulthood.

Nymphs: The juvenile, underwater stages of mayflies, stoneflies, dragonflies, and damselflies and other aquatic insects whose juvenile stages are covered by hard exoskeletons. The word can also refer to the fishing flies which imitate these creatures, in which case it is used as a blanket term for flies imitating any underwater stage of an invertebrate (except for crayfish and leeches).

Oviposit: To lay eggs.

Pharate adult: Caddisflies are considered to be pupae during their transformation from larva into adult. This transformation is complete before they're ready to emerge. The emerging insect we imitate with the "pupa" patterns we tie is technically called a pharate adult. It is a fully-formed adult caddisfly with one extra layer of exoskeleton surrounding it and restricting its wings.

Pupae: Any insect which spends most of its juvenile lifetime as a larva first becomes a pupa for a time before emerging as a fully grown adult. Depending on the species, the pupal form can be very important for fly fishermen to imitate.

Searching patterns: Any artificial fly pattern used when trout that aren't feeding selectively on anything in particular. A searching pattern may be an attractor or an imitation of something specific that the fish might favor even though it's not currently hatching.

View Full Size

Here's an underwater view of the pupal shucks of several already-emerged Brachycentrus numerosus caddisflies.

Shucks: The shed exoskeleton left over when an insect molts into its next stage or instar. Most often it describes the last nymphal or pupal skin exited during emergence into a winged adult.

Useful References:

LaFontaine, Gary. 1981. Caddisflies. The Lyons Press.

Swisher, Doug and Carl Richards. 2000. Selective Trout. The Lyons Press.