AQUATIC INSECT HATCH GUIDE
FOR TROUT STREAMS OF THE BLUE MOUNTAINS OF SOUTHEASTERN WASHINGTON AND
NORTHEASTERN OREGON : for fly fishermen
By Robert L. Newell, PhD and Dale McKain
This is a guide to the major aquatic insect hatches for
streams of the Blue Mountains of southeast Washington and northeast Oregon,
primarily the trout bearing streams of the area. The guide was developed in the years 2000-2001 at the time when Dr. Newell was an environmental biologist at the Hanford Nuclear Station in Washington, and Mr. McKain owned a fly shop in Pendleton, OR. Detailed hatch information is
provided for mayflies, stoneflies and caddisflies. Other insect groups and fly selections are
mentioned at the end of the guide.
The guide contains names of common insects, emergence=flight
periods and recommended fly patterns. This chart was developed from
several years of collecting by the authors to help fly fishermen ‘match the
hatch’ of aquatic insects to help them catch trout.
The streams of the study area flow out of the Umatilla National Forest, and the Wallowa-Whitman National Forest usually from heavily timbered, narrow steep canyons.
Eventually they flow out of the Forest eventually entering wider valleys
containing agricultural activities and homes. After they enter these wider
valleys the usual result is less gradient, warmer temperatures, increased
nutrients and sediment. For example the Touchet River drops in elevation from
3300’ near the Bluewood ski area to 1613’ at Dayton, a 20-mile distance, and
450’ elevation at its confluence with the Walla Walla River. At some point
downstream some of these streams no longer hold trout and concurrently the
insect fauna is influenced by these water quality changes. Some streams change
less (Tucannon River, Looking Glass Creek) than others (Touchet River, Mill
Creek, Walla Walla River). It is difficult to pinpoint where trout-bearing
water begins and ends and is not really important for this work. The geographic area covered by this chart is; bounded on the south by
the John Day River, on the north and east by the Snake and Columbia rivers,
and Oregon Hwy. 207 on the west.
This chart was developed from several years of collections of insects by the authors to help fly fishermen
match the
hatch. Our largest source of public prestine trout waters are in the 
Umatilla and Wallowa-Whitman
National Forests of northeast Oregon, where many days you can spend fishing
with no one in sight but the wildlife around you. When fishing for trout in this area, it is not uncommon to experience a 200+ fish hookup day. Keep in mind... while having a trout or steelhead hooking up to a dry fly, is a lot of fun; 90% of a trout's diet is sub-surface insects, plant particles, sticks and stones.
Development of hatch charts in mountainous areas of the
western U.S. is difficult due to many factors that can influence 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. Hatch densities can vary from year-to-year. Some insects will
inhabit only the upstream portions of a stream and others are found throughout
the stream system.
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 be 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.
For more fly patterns, contact your local fly-fishing shop
or one of the many excellent books on fly fishing the west. For photographs of
these insects and more workable fly patterns, use one of the many published
hatch guides written for western streams or consult such reference books
as; Hatch Guide For Western Streams, Mayflies, Caddis, the Super
Hatches, Caddisfly,
Trout Flies, Hatches II, or Fish Food, to name a few available sources.
The book Western Mayfly Hatches may be the single best source of information on
western Mayflies. Also see the excellent web site, www.troutnut.com. We have listed some of
the major insect hatches by their Latin generic and species names. We did this
to help interested fishermen to search out additional information of a
particular hatch, including photographs, from other publications or the
internet, design their own patterns based on the photos, and associate common fly
names with scientific names. Common names are notoriously inconsistent, while
Latin names are very consistent.
The book Western Mayfly Hatches may be the single best source of information on
western Mayflies. Also see the excellent web site, www.troutnut.com. We have listed some of
the major insect hatches by their Latin generic and species names. We did this
to help interested fishermen to search out additional information of a
particular hatch, including photographs, from other publications or the
internet, design their own patterns based on the photos, and associate common fly
names with scientific names. Common names are notoriously inconsistent, while
Latin names are very 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/species 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. for the species of the mayfly 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/salmonfly (Pteronarcys) hatches/emerges much
earlier in this area.
Click on this link to identify - more Stoneflies
The medium stonefly, Skwala, has no common name and is very abundant, with hatches in March and April. The term “hatch” is very generic and probably refers to when an aquatic insect leaves the water and becomes an adult (mayflies) and for others the adult may be around long after it emerged (caddisflies and stoneflies). The Blue Mountain streams can have diverse assemblages of insects. On the Touchet River alone we have collected 30 species of mayflies, 35 species of caddis and 35 of stoneflies.
Hatches of the western green drake are small and scattered in our Blue Mountains Ecoregion.
Click on this link to identify - more Mayflies.
Click on this link to identify - more Stoneflies
The medium stonefly, Skwala, has no common name and is very abundant, with hatches in March and April. The term “hatch” is very generic and probably refers to when an aquatic insect leaves the water and becomes an adult (mayflies) and for others the adult may be around long after it emerged (caddisflies and stoneflies). The Blue Mountain streams can have diverse assemblages of insects. On the Touchet River alone we have collected 30 species of mayflies, 35 species of caddis and 35 of stoneflies.
Hatches of the western green drake are small and scattered in our Blue Mountains Ecoregion.
Click on this link to identify - more Mayflies.
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 species are present for most of the fishing season. These caddis genera definitely have a "super hatch." If you fish below western dams these caddisflies can reach incredible numbers. Both of these caddisfly genera can occur in stream sections not containing trout.
Click on this link to identify - more Caddisflies.
The longest emergence/flight period and most spectacular insect of this area is the October caddis, Dicosmoecus gilvipes.
Adults can be seen from mid-September until early November. A drive up the Touchet River on any autumn evening one will see hundreds of adults of this, the largest caddisfly in the study area.
How does one use this hatch guide? One way to use these data
is to find a pattern book and tie the flies recommended in this guide. If you
want to know more, find a hatch guide that contains photographs and recommended
patterns. Many such guides have been published, such as Hatch Guide For Western Streams, Hatch Guide to the
Deschutes River, Hatch Guide to Lakes and there are several others. Further
afield there are guides for Yellowstone Park, Snake River, Bighorn River, etc.
Some of the insects found in the study area are known from other western
streams. A little research on the internet will yield scores of data sources.
For mayflies we recommend Western Mayfly Hatches by Hafele and
Hughes. With this one book you will have all of the information you need about
mayflies in the west. There are no books like this one on mayflies for
stoneflies or caddisflies although Caddis, the Super Hatches is a good,
little known book. On the internet see the web sites like; www.troutnut.com ~~~ http://www.youtube.com /watch?v=k_GZeKZ-HL8 ~~~ http://www.flycraftangling.com/index.asp?p=116 for many insect photographs, common names and
information of interest to the fisherman.
STILLWATER FLIES
Most of our high mountain lakes are not accessible until April, and some lakes above 8000' it maybe as late as July 4th before you can hike into
them. It always seems the trout are waiting for the first fly of the season
to hit the water, and then the lake will churn right before you eyes. 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), Red San Juan Worm
(12-14), and Midge Pupae (18-22) patterns. We have found the best flies
to use in our stillwaters for trout beginning in May, are wooly buggers
Elk Horn Lake Special (14) on overcast or sunny days, Blue Mountain Dragon (8) on sunny days, and a Rickards' AP Emerger (12-16) in the early am and
late pm hours.
Orange, black or brown leech patterns Wooly Bugger (6-14) work well almost anytime in stillwater. Good dry flies to use in our Blue Mountain lakes are Adams (14-22), Cream or Dun Callibaetis (10-16), Baetis/ BlueWinged Olive (10-14), 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.
We have listed all genera and species names in italics.
MONTHLY SUMMARY
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. Small black winter stoneflies can be seen crawling
along snow banks at higher elevations (Capnia,
Nemoura). The following specific insects can be expected as adults at lower
elevations; midges, mayflies like Baetis, Rhithrogena, and stoneflies
like Pteronarcys, Skwala,
and small winter stoneflies.
DRY: Baetis-Blue
winged olive and blue duns (18-20);Rhithrogena-Western March browns, hairwings, CDC, or comparaduns (10-14); Skwala stonefly, stimulator (light olive) ( 8-10, 2XL ); Pteronarcys-Salmonfly or giant stonefly, sofa pillow, stimulator, Clark's stonefly ( 4-8, 3XL); Small black winter stonefly (Capnia, Isocapnia, Nemouridae), small brown stone ( 12-16).
NYMPHS: Krystal flash nymph, Baetis nymph, pheasant tail (14-20,
2XL); Gold ribbed hare's ear, March brown soft hackle, CDC emerger (10-14);
Skwala; small golden stone (8-10
2xl); Kaufmann's black stone, black stone, Box Canyon stone (4-8, 3XL); Hare's ear, pheasant tail (12-16), prince nymph (10-14).
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=mother’s day caddis), stoneflies (Skwala, Pteronarcys, Hesperoperla), and a few mayfly (Rhithrogena-Western March
brown) hatches can be heavy, but timing is critical to see the heaviest
hatches.
DRY: Rhithrogena-Western
March Browns, CDC, or comparaduns (10-14); Brachycentrus-black caddis, Mother’s Day caddis, American grannon,
deer hair caddis (12-16); Skwala stonefly, stimulator (light olive) (8-10,
2XL); Hesperoperla, Golden stones,
orange stimulator, madam X (6-8 2XL ); Pteronarcys,
Salmonfly or giant stonefly, sofa pillow, stimulator, Clark's stonefly (4-8 3XL
).
NYMPHS: Gold ribbed hare's ear,
March brown soft hackle (10-14); Brachycentrus
larvae, herl nymph (10-16 2XL); 3-Kaufmann's stonefly (4-8 3XL), prince nymph (10-14), little brown
stone, golden stone nymph (10-6 2XL). See March for other early spring patterns to use.
MAY
By May the runoff is waning in most Blue Mountain streams. Large streams and rivers like the Umatilla River, and Grande Rhonde River, John Day River, Powder River, Wallowa and Minam Rivers 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 as days are longer and the water warms. 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: Rhithrogena, Western March Browns (10-14); Brachycentrus, black caddis (12-16); Cheumatopsyche, elk hair caddis (12-18); 3-Skwala stonefly, stimulator (olive, yellow color) (8-10 2XL); Pteronarcella, small salmonfly, orange
stimulator (8-10 2XL); Hesperoperla
& Calineuria-Golden stones (6-8
2XL).
NYMPH: Hare's ear (10-14); herl
nymph, Martinez nymph (10-16 2XL); bead head caddis, sparkle pupae (12-16); Skwala, small golden stone (8-10
2XL), Kaufmann's stonefly (8-10 2XL), golden stone nymph (6-10 2XL).
JUNE
By June the weather can be 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.
Acentrella, 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: Baetis,
blue dun (18-20); Cinygmula, red
quill, light cahill, pale brown dun, pink lady, parachute dun, comparadun
(12-16); Drunella doddsi and grandis, western green drakes (8-10); flavilinea, flavs. lesser green
drake, blue-winged olive (14-16 ); E. infrequens/E. inermis, pale morning
duns, (14-16 ); Paraleptophlebia,
mahogany duns, blue quill (12-16 ); Epeorus,
Quill Gordon, cahill (10-16); Rhithrogena,
Western March brown (a few stragglers only), (10-14 ); Cheumatopsyche,
caddis, elk hair caddis (12-18); Hydropsyche, spotted sedge-a "super hatch", elk
hair caddis (10-14 ); Skwala stonefly, end of this hatch,
stimulator ( 8-10 2XL); Hesperoperla
& Calineuria, Golden stones, end
of this hatch, stimulator (6-8 2XL); Pteronarcella,
small salmonfly, black stimulator ( 8-10 2XL ), Glossosoma little black short-horned sedge.
NYMPH: Krystal flash
nymph, Baetis nymph, pheasant tail, brown nymph, bird's nest (12-20, 2XL), olive hare's ear (8-10 2XL); 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
JULY
By July the weather is getting very hot, the streams are flowing much lower, slower, the water is warm, and the hatches are generally in late mornings through
evenings. The hatches are very similar to those seen in June with the addition
of the small yellow, tan, green, or orange summer stoneflies (Chloroperlidae=Alloperla, Suwallia or Sweltsa). Adults of the caddisflies Hydropsyche and Cheumatopsyche are present all summer long.
DRY: Baetis-Blue-winged olive, blue duns, blue-winged olive spinner
(18-20); Cinygmula, red quill,
(other patterns see above)(12-16); D.
grandis and D. doddsii, Western green drake, (small
hatches) (8-10); D. flavilinea, flavs. lesser green drakes, blue-winged olive (14-16 ); E. infrequens/E. inermis, pale morning duns ( 14-16); Paraleptophlebia, blue quill, mahogany duns (see above for other patterns)( 12-16); Epeorus, Quill Gordon, cahill, (10-16 ); Brachycentrus, black caddis and a "superhatch" (12-16 ); Cheumatopsyche caddis, elk hair caddis (12-18 ); Hydropsyche, spotted sedge and a "superhatch", elk hair caddis ( 10-14 ); Chloroperlidae-yellow sally stoneflies (10-16 2XL).
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), prince nymph (10-14)
AUGUST
This month has the dog days of summer. 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. Best fishing results seems to be late afternoon when shadows appear over gin clear waters.
DRY: Cinygmula,
Quill Gordon (10-16); E. doddsi and
E. grandis, small hatches, western
green drake (8-10); D. flavilinea,
flavs, lesser green drakes (14-16 ); E.
infrequens/E. inermis, pale morning duns
(14-16); Paraleptophlebia, blue
quill, mahogany duns(see other patterns above) (12-16); Epeorus, Quill
Gordon, cahill (10-16); Brachycentrus, black caddis (12-16); Hydropsyche, spotted sedge, elk
hair caddis (10-14 ). 
NYMPHS: Pheasant tail, 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), prince nymph (10-14), October Caddis (4 2XL), see previous months for other patterns.
SEPTEMBER
The very 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. A
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 and a close, smaller
relative, Onocosmoecus. Fishing can
be spectacular however.
 | |
| October Caddis imitation |
NYMPHS: Hare's ear, pheasant tail
(10-14), olive hare's ear (8-10 2XL), buckskin larvae, stone cased caddis
(6-10 3XL), golden stone nymph (6-10 2XL), prince nymph (10-14), see previous months for other
patterns... |
| October Caddis and a #10 Stimulator |
OCTOBER
Fall is in the air. 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 colder. 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, except for the mayfly Paraleptophlebia bicornuta that emerges later than any mayfly we
have seen. . Occasionally one is surprised on isolated stretches of streams
when a large caddis (Neophylax) hatch
occurs (tributaries of the Walla Walla and Touchet Rivers).
DRY: Neophylax, brown dot sedge, dark speckled sedge, dark elk hare
caddis (8-10 2XL), Dicosmoecus,
October caddis or giant orange sedge, orange stimulator, orange hopper patterns
(6-8 2XL); Paraleptophlebia bicornuta,
probably the last mayfly hatch of the year, a tough customer, blue quill
(12-14); Onocosmoecus unicolor,
great late summer sedge (10-12), a tough customer but never very abundant.NYMPH: bead head caddis, dark
hare's ear (8-10 2XL), buckskin caddis, stone cased caddis (6-10 3XL), golden stone (6-8 2XL).
NOVEMBER
Most stream are closed to trout fishing on November 1st in the Blue Mountain Region. Please check your Oregon and Washington fishing regulations before grabbing your rod, reel and hitting the road. This is the wettest month of the year. Snow is probable in
the upper reaches of streams early and probable in all areas by late month.
Hatches during the cold days of November are rare as freezing nights are
possible. A few stragglers of the October caddis may persist if the nights have
not been excessively cold.. Midge hatches can be expected (although many are
very small) during the milder days and it is too early for the tiny black
winter stoneflies. Midge (or chironomid) pupae patterns would be a good choice
also. There may be some large, rare caddisflies that are usually not numerous (Psychoglypha). An occasional blue dun
may be seen on a sunny day. Nymphs are probably your best bet.
Between November 1st and April 15th, most anglers turn the attention to Pacific Northwest steelhead fishing. Prehaps the best all around fly to use during this time is an articulated Egg-Sucking Leech (sizes 2-6).
Between November 1st and April 15th, most anglers turn the attention to Pacific Northwest steelhead fishing. Prehaps the best all around fly to use during this time is an articulated Egg-Sucking Leech (sizes 2-6).
DECEMBER
This is not a good time for dry flies. This is the coldest
month of the year. Occasionally, quiet, 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 chase steelhead.
Some other rivers in the Upper Columbia River Basin that we fish steelhead, usually in the forth quarter of the year.
TERRESTRIALS
River
|
Timing
|
Flies – size #2 hook
|
Gen. Location
|
Clearwater
|
Sept – Nov
| Nez Perce Indian Reservation | |
Columbia
|
Oct – Nov
|
Egg Sucking Leech
|
Ringold area
|
Klickatat
|
Sept - Oct
|
through The Canyon
| |
Grande Ronde (WA)
|
Oct – Nov
Dec - Jan |
Green Butt Skunk,
Muddler Minnow, Leeches (in winter) |
Boggan’s to Shumaker
and Stateline / Big Bend area |
Lower Walla Walla
------------ Upper Walla Walla |
Sept – Dec
---------- Dec - March | below Stateline Rd ---------- above Stateline Rd | |
Lower Touchet
------------- Upper Touchet |
mid-November
---------------
Jan - March
|
Leeches
– red and orange egg pattern w/skein – shrimp |
Lamar to Lukenbill Rd -------------------
Upstream of Lewis and Clark Park |
Grande Ronde (OR)
|
late Oct
– Nov - Jan |
Dry flies
- Leeches |
OR-WA stateline to Troy
|
OTHER INSECT GROUPS for trout fishing
- Diptera, Chironomidae=midges are common in all streams and hatches can occur about any time. Most adults are very small; Ceratopogonidae=biting midges.
- Diptera, Tipulidae=crane flies
- Diptera, Simuliidae=black flies
- Coleoptera; riffle beetles, water pennies
- Lepidoptera; aquatic moths
- Odonata; damselflies
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
(probably the most abundant terrestrial insect, especially in forested areas.)
2. Beetles,
black
3. Caterpillars,
moths, butterflies
4. Grasshoppers-many
grasshopper patterns could be taken by fish as caddis or stonefly adults.
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.
7. Tailed
frog (Ascaphus montanus) has a larvae
about 3” long and black
8. Salmon/steelhead
eggs and flesh from decaying salmon carcasses.
9. Arachnids=water
mites
This writer would also like to make reference to the other articles posted to this blog as an aid to catch BIG fish:
~ To Catch BIG fish -- Part 1 -- Gearing up, hooking, chasing and landing big fish
~ To Catch BIG fish -- Part III -- Where to go and when
This writer would also like to make reference to the other articles posted to this blog as an aid to catch BIG fish:
~ To Catch BIG fish -- Part 1 -- Gearing up, hooking, chasing and landing big fish
~ To Catch BIG fish -- Part III -- Where to go and when
UPDATED: by Dale McKain - January 2013
Tight lines and good fishing.
Walla² Fly Fishers
