AQUATIC INSECT HATCH GUIDE FOR STREAMS OF THE BLUE MOUNTAINS OF SOUTHEASTERN WASHINGTON AND NORTHEASTERN OREGON

By Robert L. Newell, Ph.D and Dale McKain, Blue Mountain Anglers & Fly Shop, LLC

This is a guide to the major aquatic insect hatches for trout streams of the Blue Mountains of southeast Washington and northeast Oregon. Some of the patterns listed here may work in lakes and ponds also. The main areas covered by this chart are; bounded on the south by the Grande Ronde River, the Snake River on the east and north, and Interstate highway I-84 on the west. This chart may work in other areas southwest and southeast of La Grande, Oregon. This chart was developed from several years of collections by the authors to help fly fishermen match the hatch.

Development of hatch charts in mountainous areas of the western U.S. is difficult due to many factors that can effect hatching times. One species may hatch weeks apart in different streams, different parts of the same stream, and some species have multiple generations per year in one area and single generations in others. A hatch will normally begin at lower elevations and hatches of the same insect will occur days later at higher elevations.

We have selected insects that are the most abundant and widespread throughout the region and throughout trout water of individual streams. Other insects may be abundant in isolated streams or portions of streams. If you are prepared to match the hatch with the patterns listed here you will ready for most major hatches throughout the fishing season. If you have comments, suggestions, or data (e.g. specimens) that will increase the accuracy of this chart, contact either author at Blue Mountain Anglers & Fly Shop, LLC in Pendleton, Oregon.

For fly patterns, contact your local fly fishing shop. For photographs of these insects and workable patterns, use one of the many published hatch guides written for western streams or consult such reference books such as; Mayflies, Caddis Super Hatches, Caddisflies, or Hatches II, to name a few available sources. These books are readily available from Blue Mountain Anglers'. We have listed some of the major insect hatches by their Latin generic name. We did this to help interested fishermen to search out additional information of a particular hatch, including photographs, from other publications, design their own patterns based on the photos, and associate common fly names with scientific names. Common names are notoriously inconsistent but Latin names are consistent.

In addition to hatches, we have listed some "non-hatches", and terrestrial insects. These non-hatches are not insects and therefore do not have adult phases that leave the water. As you use this chart, don't forget about the nymphs of this insects, emergers, stillborn duns, and pupae when appropriate. Stonefly nymphs crawl out of the water to hatch so the presence of cast skins is good evidence of a recent hatch. This chart is organized by months. For a particular hatch you will usually see the genus of aquatic insect, an appropriate dry fly, nymph pattern, and suggested size. Some genera listed here represent several species, each species may call for a different pattern, e.g. Cinygmula, we list the red quill, light cahill, pale brown dun, and pink lady to cover all of the species. There are interesting differences between streams in this area and other western trout streams. The giant stonefly hatches much earlier in this area. Hatches of the western green drake are small and scattered. The medium stonefly, Skwala, has no common name and is very abundant, with large hatches in March and April.

If we had to recommend one fly to match in this region of the west, it would be the spotted sedge, imitating the adult of the caddisfly family Hydropsychidae, including Hydropsyche, and smaller Cheumatopsyche, which are the most common insects in Blue Mountain Streams. One or more species of these caddis are present for most of the fishing season. These caddis definitely have a "superhatch."

Most of our high mountian lakes are not accessible until May, and sometimes it maybe as late as Memorial Day Weekend. The lakes and ponds that can be reached in March and April can be best fished with Chironomids (16-20), Pheasant Tail Nymphs (18-22) and Midge Pupae (18-22) patterns. We have found the best flies to use in our stillwaters for trout beginning in May, are the Blue Mountain Dragon (8) on sunny days, an Elk Horn Lake Special (12-16) on overcast/ sunny days, and an Rickards' AP Emerger (12-16) in the early am and late pm hours. Black or brown leech patterns Wooly Bugger (6-10) work well almost anytime in stillwater. Good dry flies to use in our Blue Mountain lakes are Cream or Dun Callibaetis (10-16), Baetis/ B.W.O. Hatch (10-12), Comparadun Gray/Sulphur (14-18) P.M.D, Trico Spinner (14-22). Many lakes hold crayfish in the 2"- 4" range, most in a green to amber coloration.

MARCH

Winters are mild at lower elevations of the Blue Mountains and spring comes early, while the snow can impede fisherman movement at higher elevations. Runoff is usually greatest in late winter as rains cause snowmelt and high, turbid streams. While Rocky Mountain streams may be high into July, Blue Mountain streams are dropping in May. There are prolific hatches in the late winter. The popular salmonfly begins hatching much earlier in this region than elsewhere in the west. The following specific insects can be expected as adults; midges, mayflies like Baetis, Rhithrogena, and stoneflies like Pteronarcys, Skwala, and small winter stoneflies.

DRY: 1- Baetis-Blue winged olive and blue duns (18-20); 2-Rhithrogena-Western March browns, hairwings, CDC, or comparaduns (10-14); 3-Skwala stonefly, stimulator (light olive)
(8-10, 2XL); 4-Pteronarcys-Salmonfly or giant stonefly, sofa pillow, stimulator, Clark's stonefly (4-8, 3XL); 5-Small black winter stonefly (Capnia, Isocapnia, Nemouridae), small brown stone (12-16).

NYMPHS:1- Krystal flash nymph, Baetis nymph, pheasant tail (14-20, 2XL); 2-Gold ribbed hare's ear, March brown soft hackle, CDC emerger (10-14); 3-Skwala; small golden stone (8-10 2xl);4-Kaufmann's black stone, black stone, Box Canyon stone (4-8, 3XL); 5-Hare's ear, pheasant tail (12-16).

APRIL

Streams can be high and dirty in April, some streams are closed to fishing and, dry fly fishing can be impossible. The weather will dictate the actual stream/fishing conditions. Warm weather and/or rain will turn most streams high and muddy. Some of the caddisfly (Brachycentrus), stoneflies (Skwala, Pteronarcys, Hesperoperla), and a few mayfly (Rhithrogena-Western March brown) hatches can be heavy.

DRY: 1-Rhithrogena-Western March Browns, CDC, or comparaduns (10-14); 2-Brachycentrus-black caddis, American grannon, deer hair caddis (12-16); 3-Skwala stonefly, stimulator (light olive) (8-10, 2XL); 4-Hesperoperla, Golden stones, orange stimulator, madam X (6-8 2XL); 5-Pteronarcys, Salmonfly or giant stonefly, sofa pillow, stimulator, Clark's stonefly (4-8 3XL)

NYMPHS: 1-Gold ribbed hare's ear, March brown soft hackle (10-14); 2-Brachycentrus larvae, herl nymph (10-16 2XL); 3-Kaufmann's stonefly (4-8 3XL),4-little brown stone, golden stone nymph (10-6 2XL). See March for other patterns (5).

MAY

By May the runoff is over or waning in most Blue Mountain Streams. Large streams like the Umatilla River may still be high and dirty however. By the end of May hot weather is close at hand and the majority of hatches will be happening. Some of the species seen in April are still hatching along with some other caddis (Cheumatopsyche), and stoneflies (Pteronarcella) in May. Pteronarcella is the smaller identical cousin of the giant stonefly.

DRY: 1-Rhithrogena, Western March Browns (10-14); 2-Brachycentrus, black caddis
(12-16); 3-Cheumatopsyche, elk hair caddis (12-18); 3-Skwala stonefly, stimulator (olive color) (8-10 2XL); 4-Pteronarcella, small salmonfly, orange stimulator (8-10 2XL); 5-Hesperoperla & Calineuria-Golden stones (6-8 2XL).

NYMPH: 1-Hare's ear (10-14); herl nymph, Martinez nymph (10-16 2XL); 2-bead head caddis, sparkle pupae (12-16);3-Skwala , small golden stone (8-10 2XL), 4-Kaufmann's stonefly (8-10 2XL), 5-golden stone nymph (6-10 2XL).

JUNE

By June the weather is hot at low elevations, the streams have dropped and cleared and the mayfly hatches are beginning in earnest. We have seen simultaneous hatches in early June of several kinds of mayflies (e.g. Baetis, Drunella, Ephemerella, Paraleptophlebia, Rhithrogena and Epeorus), caddisflies seen in earlier months, and some stoneflies. Matching the hatch can be easy or hard during these conditions. Multiple hatches are common.

DRY: 1-Baetis, blue dun (18-20); 2-Cinygmula, red quill, light cahill, pale brown dun, pink lady, parachute dun, comparadun (12-16); 3-Drunella doddsi and grandis, western green drakes (8-10); 4-D. flavilinea, flavs., lesser green drake, blue-winged olive (14-16); 5-E. infrequens/E. inermis, pale morning duns, (14-16); 6-Paraleptophlebia, mahogany duns, blue quill (12-16); 7-Epeorus, Quill Gordon, cahill (10-16); 8-Rhithrogena, Western March brown (a few stragglers only), (10-14); 9-Cheumatopsyche, caddis, elk hair caddis (12-18); 10-Hydropsyche, spotted sedge-a "super hatch", elk hair caddis (10-14 ); 11-Skwala stonefly, end of this hatch, stimulator (8-10 2XL); 12-Hesperoperla & Calineuria, Golden stones, end of this hatch, stimulator (6-8 2XL); 13-Pteronarcella, small salmonfly, black stimulator
(8-10 2XL).

NYMPH: 1 & 2, 4-8-Krystal flash nymph, Baetis nymph, pheasant tail, brown nymph, bird's nest (12-20, 2XL), 3-olive hare's ear (8-10 2XL); 9 & 10-bead head caddis, sparkle pupae (10-16), Kaufmann's golden stone (6-8 3XL), black stone nymph (8-10 2XL), see previous months for previously listed organisms and patterns.

JULY

By July the weather is getting very hot, the streams are now low, the water is warm, and the hatches are generally in the mornings and evenings. The hatches are very similar to those seen in June with the addition of the small yellow, tan, and orange summer stoneflies. This is hopper time; the end of the month usually fishes very successfully with hopper in the early to late afternoons.

DRY: 1-Baetis-Blue-winged olive, blue duns, blue-winged olive spinner (18-20);2-Cinygmula , red quill, (other patterns see above)(12-16); 3-D. grandis and doddsi, Western green drake, (small hatches) (8-10); 4-D. flavilinea, flavs., lesser green drakes, blue-winged olive (14-16); 5-E. infrequens/E. inermis, pale morning duns (14-16); 6-Paraleptophlebia, mahogany duns (see above for other patterns) (12-16); 7-Epeorus, Quill Gordon, cahill, (10-16); 8-Brachycentrus, black caddis and a "superhatch" (12-16); 9-Cheumatopsyche caddis, elk hair caddis (12-18); 10-Hydropsyche, spotted sedge and a "superhatch", elk hair caddis (10-14 ); 11-Chloroperlidae-yellow sally stoneflies (10-16 2XL), hoppers (6-12)..

NYMPHS: Krystal flash nymph, Baetis nymph, pheasant tail, bird's nest, bead head nymphs, hare's ear, (14-20, 2XL), olive hare's ear (8-10 2XL), bead head caddis, sparkle pupae (10-16), little yellow stone (10-14 2XL), see previous months for hatches previous listed..

AUGUST

This month has the dog days of summer. August is full blown hopper season. Almost anywhere from late morning to late afternoon hoppers are clicking throughout our meadows and sitting on the streamside grasses. The days can be extremely hot and the evenings warm. The streams are very low and warm. The hatches will be early and late in the day, primarily mayflies, with some caddis and a few summer stoneflies, similar to what is listed for July. Shady, cool canyons could see some mid-day hatches.

DRY: 1-Cinygmula, Quill Gordon (10-16); 2-E. doddsi and E. grandis, small hatches, western green drake (8-10); 3-D. flavilinea, flavs, lesser green drakes (14-16); 4-E. infrequens/E. inermis, pale morning duns (14-16); 5-Paraleptophlebia, mahogany duns(see other patterns above) (12-16); 6-Epeorus, Quill Gordon, cahill (10-16); 7-Brachycentrus, black caddis (12-16); 8-Hydropsyche, spotted sedge, elk hair caddis (10-14 ), hoppers (6-10).

NYMPHS: Pheasant tail, light & dark hare's ear, bead head, bird's nest (14-20 2XL), olive hare's ear (8-10 2XL), bead head caddis, sparkle pupae (10-14 2XL), see previous months for other patterns..

SEPTEMBER

The real hot weather is over but the days will still be very warm and bright. Most of the major mayfly hatches start to wane in September. I few leaves will be starting to turn color and the streams will be very low unless some fall rains have occurred. As the days and nights cool, hatches will occur mid-day again. Toward the end of the month, in cool shaded canyons and at higher elevations the mornings and evenings are too cold for insects to fly and mid-day will provide the only hatches. Fewer hatches will occur as the month proceeds including the appearance of the largest caddis in the area, Dicosmoecus (the October Caddis). Fishing can be spectacular however.

DRY: 1-Baetis, blue wing olives and duns (18-20); 2-D. doddsi and D. grandis, small scattered hatches (8-10); 3-E. infrequens/E. inermis, pale morning duns (14-16); 4-Paraleptophlebia, mahogany duns (12-16); 5-Brachycentrus, black caddis (12-16); 6-Hydropsyche, spotted sedge, elk hair caddis (10-14); 7-Dicosmoecus, October caddis or giant orange sedge (6-8 2XL); 8-Claassenia, fall stonefly, we are calling it the cream stonefly, orange and yellow hopper patters, yellow stimulator (6-8 2XL).

NYMPHS: 1-Hare's ear, pheasant tail (10-14), 2-olive hare's ear (8-10 2XL), 7-buckskin larvae, stone cased caddis (6-10 3XL), 8-golden stone nymph (6-10 2XL),see previous months for other patterns..

October Caddis
(eyeball to tail length is 1-1/4 inch )

OCTOBER

Fall is in the air. This is truly October Caddis time. Toward the end of the month, frost is possible and perhaps an early dusting of high elevation snow can occasionally be seen. The nights are longer and cold. Fall rains can dirty the water and knock leaves into the water making nymph fishing difficult. The stream water is cold and a few sporadic hatches will occur for a few hours during the warmest part of the day or sunniest reaches of streams. Some fishing seasons close at the end of this month. With the possible exception of the October caddis hatches, none will be spectacular. Occasionally one is surprised on isolated stretches of streams when a large caddis (Neophylax) hatch occurs ( tributaries of the Walla Walla and Touchet Rivers), along with the large fall stonefly (Claassenia) which, however, is relative secretive and hard to spot.

DRY: 1-Neophylax, dark speckled sedge, dark elk hare caddis (8-10 2XL), 2-Dicosmoecus, October caddis or giant orange sedge, orange stimulator, orange hopper patterns (6-8 2XL); 3-Claassenia, large cream stonefly, yellow stimulator, yellow or white hopper patterns (6-8 2XL).

NYMPH: 1-bead head caddis, dark hare's ear (8-10 2XL), 2-buckskin caddis, stone cased caddis (6-10 3XL), 3-golden stone (6-8 2XL).

NOVEMBER

Hatches during the cold days of November are rare. Midge hatches can be expected and it is too early for the tiny black winter stoneflies. Midge (or chironomid) pupae patterns would be a good choice also. There are some large, rare caddisflies that are usually not numerous, and midge hatches can occur at times. An occasional blue dun may be seen on a sunny day. Nymphs are probably your best bet. Northeast Oregon has two (2) open trout streams year around - McKay Creek near Pendleton and Powder River near Baker. Note: trout season closes in all anadromous streams and rivers in Northeast Oregon effective November 1. All accessible stillwater lakes and pond are fishable year around for trout fishing, unless noted otherwise in the Oregon Dept. of Fish and Wildlife regulations. Steelhead season opens on most rivers in the Northeast Zone effective September 1.

DECEMBER

This is not a good time for dry flies. Occasionally, quite, sunny winter days will provide some short hatches of midges or an occasional blue dun. A few tiny black winter stoneflies can often be seen on the snow. The water is very cold and the fish are inactive. Winter rains can turn most streams turbid. Nymphs are the best choice. One might do better tying flies for next season or chasing steelhead. Northeast Oregon has two (2) open trout streams year around - McKay Creek near Pendleton and Powder River near Baker. All accessible stillwater lakes and pond are fishable year around for trout fishing, unless noted otherwise in the Oregon Dept. of Fish and Wildlife regulations.

TERRESTRIALS

Several insects that do not live in water, can offer great summer fishing opportunities. You should always have a few patters to imitate the following terrestrials:
1. Ants
2. Beetles, black
3. Caterpillars
4. Grasshoppers-many grasshopper patterns could be taken by fish as caddis or stonefly adults. A #8 or #10 orange stimulator is the best fly to use for these imitations.

NON HATCHES

Consider carrying and fishing patterns for the following critters that do not hatch or are not insects:
1. Crayfish-crayfish are common in most streams of the reference area. These brownish orange creatures can get up to two inches long in the fall.
2. Leeches
3. Snails
4. Scuds or often erroneously called "freshwater shrimp"
5. Minnows, sculpins, eggs (salmon or steelhead), or small trout.
6. Worms-all the local streams contain small aquatic worms up to 1 inch long that look much like common earthworms found in your garden. A #6 or #8 San Juan Worm is the best fly to use for this imitation.

Hatch Guide II- DRAFT-4 RLN 2/14/01© copyrighted

email

page © Copyright 2003-2005
all rights reserved,
no reproductions without
written permission from the authors
author: Rod McDougall