Bugs, Entomology, Habitat, Presentation & Patterns
In an effort to provide education, fly-tying instruction and a better understanding on what trout eat I am providing these resources. Please click on a pattern below to view the full content of entomology, fly-tying direction, practices and video.
Disclaimer: Clay Hash is not a professional entomologist and is a working class fly fishing guide and fisherman that knows how to match your flies with the bugs on the Lower Yuba River.
Bug Quick Links
You can get information about the common bugs that are encountered here in Northern California by selecting the links below. Use the Select Box below to jump to a specific bug.
The Mayfly Complex
The last few times that I’ve fished the Lower Yuba River I have run into a fairly strong hatch of Blue Wing Olives or BWO’s as we affectionately call them, most of the time I call them “those darned BWO’s”. I’ve seen them coming off, but can I catch one of the fish that are eating them. Forget-about-it.
I’m usually rigged up with my 6 weight and nymphs, shot and all when I run into a hatch. So I’m not really set up right to start casting dries, emergers, cripples, or soft hackles like I should be…..
Even though the bugs often hatch in godawful weather and us fly fishers have spent many a March afternoon shivering, fishing a run as droplets of cold rain run down the sleeve of our casting arms, we would do it again tomorrow. We’d rather be there suffering and attempting to catch fish. As the month of March begins to wind down the hatches of Blue Wing Olives, “Baetis” and Skwala Stones, “Perlodidae," have been going on steadily since February a new player shows up. As late March and April arrives the days will typically start warming and the water temperatures will also go up which triggers the March Brown mayfly to start hatching. They can hatch in just about any weather. This is the “Rithrogenia Morrisoni” hatch. This large mayfly . . .
On the Lower Yuba River we have been seeing glimpses of what is coming as the season progresses and the temperatures start to warm up. On warmer days there have been PMD’s floating on down the river. It seems to me that in the last couple of years that they are coming earlier in the season then I remember from years ago. Here’s some stuff to get you prepared. Start cleaning those dry lines and organize your fly boxes.
There is a PMD hatch that starts in early spring sometimes as early as February if the weather warms up. This is one of the better hatches on the Lower Yuba . . .
Each summer I would fish a run on the Lower Yuba River with caddis emergers and soft hackles in the evenings. We had many days with plenty of fish up in the water column and taking our presentations and running up and down the river. About 45 minutes until dusk we would say “Let’s head for the honey hole”. This was a big back eddy on the way back to the truck. It was a large reversing eddy and each evening right at dusk the PED’s would start coming off. You could tie on a soft hackle and cast it into the main flow headed downstream and it would work its way into the eddy water. Trout would just sit there waiting for the PEDs. You just had to let them take it and lift your rod slowly but deliberately and fish-on. This would go on even after dark and we would be landing fish by headlamp. This became a regular routine. If you haven’t tried this you should.
When the PMDs are out and about on the Lower Yuba River there, a pattern that is often mentioned to imitate the duns are “Pinkies”. They work. But the pattern is really a pattern designed to imitate the “Epeorus” mayflies.
These yellow mayflies are important on many streams throughout the West. Here on the Lowewr Yuba they are around but not in great numbers. Even though it is not a well known insect, the hatches are not prolific and typically don’t occur on flat “technical” water. However, The Epeorus will be found in the swiftest portion of the river, and trout see enough of them to recognize them as food.
Their need for abundant oxygen and pollution-free waters restricts them areas of the river that has the best water quality. I believe that’s why they seem to be more prevalent in the upper stretch of the Lower Yuba.
As far as the Slate Drake and the Gray Drake Mayflies are concerned,there seems to be some debate as to what genus that the larger Gray or Slate colored mayflies we come across on the Lower Yuba really are. The concensus is that they are Drakes. Are they the genus Siphlonurus or are they the genus Isonychia? I’m not an entomologist so the best I can do is research.ccording to the information in the book “Flyfishers Guide to Northern California” put together by Seth Norman, the chapter authored by our local Ralph Wood, states that they are Gray Drakes or Siphlonurus occidentalis. Hogan Brown has remarked that there is a minor Isonychia hatch on the Lower Yuba . . .
Tricorythodes or Tricos are members of the crawler group of mayflies. There are nine species of Tricorythodes found in the western states. Only one Tricorythodes minutus is of importance to fly fishers. Tricos are the smallest mayflies in North America, but their hatches and spinner falls are so heavy that the largest trout in the stream will move up to feed on the surface. Their principal importance is in the spinner stage, when they can coat the surface and get trout to start feeding heavily. The duns, especially the females, can be important during early morning hatches. If you don’t get out early you may be missing the most fishable part of the hatch. The Tricos males and females are slightly different in size and quite different in color.
The Caddis Complex
When I think of the Mothers Day Caddis which is the American Grannom of the Brachycentrdae family of caddisfly, I think of the day I had on the Lower Sacramento River in April a few years ago.
I was checking out the message board for NCFFB and came across some photos that had been taken the day before. There were rafts of caddis flies in the photos, I mean thousands.I called “The Fly Shop” in Redding to see what was up. They told me that the spring caddis were coming off big time and that it might last a week or two at the most. When this happens on the Lower Sac . . .
Each year I always look forward to summer and the hydropscyche caddis hatches. This bug is also commonly referred to as “the summer caddis” the “spotted sedge” or the “net spinning caddis”. On the Lower Sacramento River the bug takes on a brown or cinnamon cast. On the Lower Yuba River the bugs tend to have a green cast. The summer evenings will find active feeding fish willing to take caddis emergers and soft hackles. It is my favorite hatch of the year.
Each summer when the temperature hits the century mark or hotter in Redding, its time to make a trip . . .
The two larval species most imitated by anglers are Rhyacophila (green caddis or green rockworms) and Dicosmoecus (October caddis). However, the effort may be misplaced because these are not the caddis larvae most consumed by trout.
Rhyacophila are common in extremely fast riffles on medium-sized streams, and while trout sometimes feed heavily on the larvae, it’s usually during the low light conditions near dawn and dusk. Most anglers cast imitations in water that is too slow or during the wrong times of the day.
Green rockworms (green caddis larvae) draw a lot of attention from anglers, perhaps because they have a common, recognizable name. The attention is unwarranted, and should be directed to other green colored larvae, especially netspinners ( Hydropsyche) in our area. Nonetheless, a nymph box without green rockworm imitations is like a golf bag without a sand wedge: when you need one, you really need one.
The Stonefly Complex
It’s late January and the word on the streets is that the Skwalas are out. It’s time to tie up some big bugs and get ready. The last time I fished the Yuba I picked up a couple of nice fish with a Mercer’s Skwala Nymph. It’s a good one.
The Skwala activity on the Lower Yuba River can start as early as late December and then transitions to “strong” activity beginning mid February and generally lasting until mid April. The Skwala is a very important hatch in that it is the first big meal of the season. Regardless of how many adults there are, the fish know they are there . . .
The Lower Yuba River has what I would classify as a minor population of little yellow stoneflies.
The Upper Yuba River and the Truckee River has a major population. For this reason geting to know the The Little Yellow Stonefly is a good idea. The “Isoperla” nymphs live in riffles and rocky runs with moderate to fast flows. They are sometimes knocked loose and drift in the current, so a nymph imitation can be sometimes be productive when dead-drifted through riffles and runs.
The “Isoperla” nymphs live in riffles and rocky runs with moderate to fast flows . . .
Golden Stoneflies behave in a manner similar to salmonflies, but they are a tad smaller.
Nymphs are large and live in riffles and rocky, bouldery areas with moderate to fast current. They often lose their grip and are taken all year by trout. An appropriate pattern dead-drifted near the bottom is effective. Choose your imitation carefully, however. Many fly shops sell a golden stonefly nymph that is golden in color, but the actual nymph is mottled shades of tan, black, and brown. However, when golden stonefly nymph molt, the new instar can briefly be a much brighter color . . .
The “Callibaetis” Mayfly is of great importance if you are going to be fishing stillwaters. The number one mayfly that you need to be familiar with is the Callibaetis. They are the most important stillwater mayfly of all. There are some respected anglers here in Northern California that believe that there is no insect more important to the stillwater angler.