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> > Correct hatch time of year Hydropsyche slossonae?

This topic is about the Caddisfly Species Hydropsyche slossonae.

The Discussion

AndyVAugust 26th, 2022, 3:05 am
Twin Cities

Posts: 9
I've seen hatch charts (e.g. DNR hatch chart for SE MN) stating mid-May til the end of July vs June (from this site). Can anyone confirm?
MartinlfAugust 27th, 2022, 8:10 pm
Palmyra PA

Posts: 3233
Possibly, but not me. Many caddis emergences seem to me much less well known, and possibly less predictable than most mayflies. Let's see if Roger or Konchu notice this post.
"He spread them a yard and a half. 'And every one that got away is this big.'"

--Fred Chappell
TaxonAugust 28th, 2022, 12:54 pm
Site Editor
Royse City, TX

Posts: 1350
Hi Andy-

Although I have no personal experience with emergence timing of mid-western caddisflies, Gary LaFontaine certainly did. In his classic book CADDISFLIES, on page 180, he lists Hydropsyche slossonae as having significant emergence on Woods Creek - Wisconsin (Florence County) from ~MAY 10 through ~AUGUST 20. Hope this helps answer the question you posed. :-)
Best regards,
Roger Rohrbeck
WiflyfisherSeptember 3rd, 2022, 7:21 pm

Posts: 663
Hatch charts are all somewhat speculative, even my own for NW Wisconsin. When you try to cover a region no two rivers are the same. Then throw in climate changes and the fact some years are vastly different temperature and precipitation wise versus other years.

Personally, I would not compare Wood Creek in northern Florence County to any stream in the southern Driftless region, In the defense of Roger, he would not know that since he is out West. Gary LaFontaine did not do all his own research across the country; he did have helpers he relied on.

For example, my observations are based on my 40+ years on specific NW Wisconsin trout streams. Was I there observing every day? No. I did stream aquatic insect sampling, talking with friends to make my best guess to start and end dates. Hatch dates were never the same from year to year and my notes proofed it, but neither was the weather or stream conditions (including stream water temperatures).

The best answer in my opinion is make your own observations for your local streams.

John S.
Jmd123September 4th, 2022, 9:23 am
Oscoda, MI

Posts: 2611
Yes, learning your streams helps a lot. Things are NEVER the same from year to year. It pays to find a "home stream" that you can fish for several years to learn the variables.

In my "natal" trout stream, the Maple River in northern lower Michigan, there was a large log in the middle of the channel, and every year it was 50-100 yards further downstream. So if the river itself changes from year to year, how can we expect other conditions to be the same from one year to the next?

Like our collecting trips to southern Indiana: each is just a snapshot in time, and what happened before our 1st trip or since the 2nd...??? You need YEARS of data to see what's really going on. Flood years? Drought years?

Just my 2 cents...CARRY PLENTY OF FLIES!!! At least until you know what to expect at a given time of year.

No matter how big the one you just caught is, there's always a bigger one out there somewhere...
MartinlfSeptember 4th, 2022, 1:53 pm
Palmyra PA

Posts: 3233
Just my 2 cents...CARRY PLENTY OF FLIES!!!"

That certainly made me chuckle. Has one or more of us, more than once, gone to a stream loaded down with flies, only to have something new hatching, fish eating, and nary a hookup?

"He spread them a yard and a half. 'And every one that got away is this big.'"

--Fred Chappell
Jmd123September 4th, 2022, 8:28 pm
Oscoda, MI

Posts: 2611
I had the wrong Hendricksons once...the pattern calls for "wood duck wing" which ended up being too yellow to match the naturals...flies floating down, splashy rises, 2 hits for me & no hookups...regular grey Mallard wing works much better! Next time...

No matter how big the one you just caught is, there's always a bigger one out there somewhere...
WiflyfisherSeptember 5th, 2022, 4:12 am

Posts: 663
I remember years ago standing at the top of a run when all of a sudden, a rather large yellowish mayfly dun popped up on the water right at my feet. As I stood there stunned starring at the large mayfly drifting by me a large gulp and it was gone. Then another and another large mayfly appeared, and each was devoured by large gulps right at my feet. All the fly boxes I carried then, and I had nothing even close to those mayflies. I stood and watched in amazement. It lasted maybe 10 minutes, and it was over. My guess was they were Potamanthus distinctus.

I have never witnessed that hatch again, but I did tie some dry flies to match that hatch. In June for many years, I did carry that yellow fly pattern with me just in case.
John S.
MartinlfSeptember 8th, 2022, 7:33 pm
Palmyra PA

Posts: 3233
John, you are not the only one to have such an experience. One of my fishing buddies, Mike, has an identical story. He's carried that pattern for years.
And he's never seen them again either.
"He spread them a yard and a half. 'And every one that got away is this big.'"

--Fred Chappell
WiflyfisherSeptember 9th, 2022, 1:36 pm

Posts: 663
Louis, a few days ago someone asked me about when the Hendrickson has "usually" starts. I commented back with a question: "What is usual anymore?"

I have witnessed on my local freestone rivers a 30-day swing. Meaning, depending on the year it could start anywhere within a 30-day time period. Some years we have a really late Winter, while in other years a very early, hot Spring.

Sometimes fly fishers I chat with on the streams say the hatch never occurred that year, when it may have occurred at a different time, or the insects popped in mass over a very shorter time period. Or. floods have affected the habitat and the insects have not re-adapted yet.

My notes go way back on certain Midwest hatches. I do feel today, the hatches on our northern freestone streams are less predictable than they used to be. Plus, we have a lot fewer major snowstorms then when I was growing up.

Even out West... last year in mid-June was outstanding, while this year tremendous flooding. Now out West it has been very hot and dry, and my friends out in the West Yellowstone are crying rain.

Right now, I am researching the Great Autumn Brown Sedge and trying to predict when they will hatch on our local Midwest rivers. The stick cases are sealed, and the pupae are developing quickly.

John S.
AndyVOctober 11th, 2022, 9:28 pm
Twin Cities

Posts: 9
Yea, I look at it this way.
1. Rely on your own observations.
2. Compile data based on your and other observations.
3. Check fly shop boards and other boards before I go.

The more reliable data, the better. You will get a Min and Max date and often within that range a more certain period where you have a high confidence level that a certain insect may be on the water and some hatches can be more predictable than others. Like many in this post have stated, there are a ton of factors that will go into emergence, including water temperature (both current and annual), weather, etc. I know certain insects have a tendency to spawn during certain periods of the year so that gives me a key as to what to put in my fly box when I go (having way too many flies, I've tried to simplify when I hit a specific stream during a specific time of year). As for the Giant Autumn Sedge, the only way I found out it even hatched on one of my streams was getting smacked in the face by one late one evening a few years ago as I was leaving and then having an incredible hour or so of fishing. To me, it's every bit as fun as a Hex hatch

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