|....................... .................... ...Fly Fishing Yellowstone National Park
New KISS Bug Series - Part 32
White Miller Caddisfly
In our opinion, trout don't eat the White Miller larvae to the extent we feel like an imitation of them is a
feasible fly to use. The larvae are probably eaten by trout to some degree but as just to what extent is
unknown. I know the larva cases are shaped long and apparently, or at least may be made in nature that
way as a means of preventing the trout from eating them.
The first time I encountered a White Miller in Yellowstone National Park (I think it was on the Firehole
River), I grabbed the little caddisfly and told Angie it was a White Miller. She says "I thought that was an
eastern trout stream bug". I thought for a second or two and replied "yes, your right". This is a long horn
caddis but not a White Miller. It worried me, so that night in the cabin I looked it up in a book I had with me
to find the book saying the White Miller was an eastern caddisfly. Well, the bottom line to this is the
caddisfly is found nationwide. Little has been written about the White Millers of the western trout streams
but I know now there's not any difference. There are more than one species but they all are very similar.
Over the last ten to twelve years, the White Miller population seems to have gone up in Yellowstone. They
are now more plentiful than the Spotted Sedges much of the season. I'm not sure anyone knows but I hope
it isn't due to a warming trend. The Madison, lower Gibbon and Firehole Rivers have huge numbers of
The pupae hatch on the surface but do so for the most part in the evenings. They will start late in the day
after the sun has set. If it's very cloudy or overcast, they may begin earlier in the afternoon. Our best
catches from fishing both the pupa and adult imitations have come just about the time it is getting dark.
These caddisflies exist mostly in smooth flowing sections of streams, or at least more so than pocket water
or fast water streams. They can be found in the slow areas and pools of some pocket water streams. Most
everywhere we have encountered them has been in streams with slow to moderate water. Often the
water has a lot of vegetation but I don't think that's a requirement for them. We have found them in some
eastern streams that seem to be void of vegetation.
We have had variable results with imitating the pupa. It seems they only emerge in some streams when it is
completely dark. We have not tried fishing at night during the hatch but we have been told by
knowledgeable anglers trout can be caught at night during the hatch.
We add just a little weight a few inches above the pupa fly. The idea is to imitate the pupae from the time
they swim to the surface of the water until they shed their pupal shuck. Most of the time the trout will eat the
fly when it is near or in the surface skim.
Present the pupa imitation using a down and across presentation. Mend your line as soon as the fly hits
the water to get the fly down some. Allow the fly to swing downstream directly below your position much like
fishing a soft hackle fly or swinging a wet fly. Stop the swing and the rod tip at about a 45 degree angle
above the horizon and let the fly come back to the surface. The current will do this for you. This is the point
at which most strikes occur. Sometimes that will take the fly a few seconds after it reaches the surface but
leaving it there very long doesn't seem to produce good results. .
Availability to trout:
Type of water:
Duration of hatch period:
Tube Case Makers
Moderate to slow - smooth and broken surface
Late Afternoons, mostly evenings